Honda-SOHC

SOHC.co.uk Forums => Project Board => Topic started by: Underdog1 on July 23, 2016, 09:45:10 PM

Title: CB750 Barn find project - First Timer
Post by: Underdog1 on July 23, 2016, 09:45:10 PM
Hi guys,

I taking delivery of a 1976 CB750 tomorrow which is a non runner from a dry US state, something for me to spend my spare time tinkering with. Needless to say i have naff all history with this bike.

According to the seller it has good compression and when fed a few squirts of ether it fires and tries to start & run. My mechanical expertise are basic from doing various jobs on cars, and I've bought this bike to actually develop some better mechanical know how.

As i don't know the history of why this bike was stored in the first place I'm a little reluctant to start trying to fire her up straight off the bat - Can anyone give me any damage controlling tips on what i should check beforehand?

My first job will be to tear down and refurb the carbs, hopefully this will get her at least ticking over. Only time will tell hey!


(https://s32.postimg.org/p5jup0pr9/item237221_0.jpg)
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: JamesH on July 23, 2016, 09:51:28 PM
Welcome to the forum, and looks like you've bought a DK special. Looks like a good base to start with....
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Johnwebley on July 23, 2016, 09:52:26 PM
first,

  get a manual,with that read it and check ALL the bike over,

 renew brake fluid,engine oil and filters,

 beware of stripping the carbs if you don't know what you doing,

 spend time learning about the bike,before you touch it,


BTW,we love pictures on here,the more the merrier,

PS,Welcome the the wonderful world of sohc,lots of friendly people here,with stacks of expert advice,
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Underdog1 on July 23, 2016, 10:11:02 PM
Welcome to the forum, and looks like you've bought a DK special. Looks like a good base to start with....

Hah yeah bang on. Pretty much the same description on all their imports!

first,

  get a manual,with that read it and check ALL the bike over,

 renew brake fluid,engine oil and filters,

 beware of stripping the carbs if you don't know what you doing,

 spend time learning about the bike,before you touch it,


BTW,we love pictures on here,the more the merrier,

PS,Welcome the the wonderful world of sohc,lots of friendly people here,with stacks of expert advice,

Cheers mate, yeah I've got a tatty second hand haynes manual ready for it. Im pretty mechanically minded so will hopefully get things figured out. Just didn't want to make a catastrophic mistake at the start line firing it up when theres no engine oil or something  ;D
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Trigger on July 23, 2016, 10:11:40 PM
Welcome to the mad world of the SOHC. Met a guy a couple of days ago at a café on the coast that just bought a CB750K1, USA import. He was telling me that he only rode the bike 7 miles to the MOT station when the top end went wrong, due to the oil jets blocking. So, at least remove the sump to see what state the engine is in. Enjoy :)
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: MarkCR750 on July 24, 2016, 12:25:51 AM
Trigger is talking about the most worrying feature of these engines, if the jets are blocked it'll eat it's cam, so you either take the engine out and strip down to check the jets are clear, or clean the carbs change the oil and fire it up with a couple of tappet covers removed to see if there is oil splashing about the rocker area, if you remove the tappet covers before you do anything else and see residual oil in there it's a positive sign but not a guarantee, as trigger said it can get nasty!, I took the risk on mine and fired it up, happily plenty of oil getting to the top, but it's a call only you can make!.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: AshimotoK0 on July 24, 2016, 07:12:50 AM
Hi welcome from me too .. a nice friendly bunch on here.

Start by downloading this. It's a big file but has the relevant parts/service manuals.

https://www.dropbox.com/s/anpzqn2r55f1o9k/CB750%20Mega%20Parts%20Service%20and%20More.pdf?dl=0

I recognize that turntable at DK !

My advice is to strip the motor, at least the top end. My mate bought a 3k mile 500/4 from them a few months back but it didn't have a centre cable in the speedo cable ! It's obviously a very low miler but not 3k). He's fannied around trying to get it to run properly without stripping any of it but he's now stripping it. Same with the 9k mile CB350 I got from them . 'Weather seized from standing for umpteen years' , in their description. When I stripped it I found a big split pin jamming the gearbox (none used in that engine !) , so not weather seized at all ( Oh and a dried up wasp in the gearbox). I wish they wouldn't give bikes ' a few snort of ether' . God knows what damage it would do if the engine starts up after being stood for typically 30 years..
Don't get me wrong, I think the bikes from DK are sometimes great deals and the guys there are great to deal with, but some of their bikes look like them came from open air USA scrapyards plus they remove/swap bits themselves, plus the Yanks are notorious for not changing oil and tinkering, giving up and ditching the bike. After all the bikes were not work transport but mainly recreational vehicles.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: onethumb on July 24, 2016, 10:20:19 AM
Welcome to a new world order where old bike rule.
Thanks for the link ashimoto.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Honda Al on July 24, 2016, 10:35:11 AM
Welcome. What's not known on this site about our bikes isn't worth knowing!

I've bought two DK specials now. Pleased with both of them. My CL350 was described in exactly the same way, but after checking it over and putting a new battery in it started straight away and I rode up the road with it. I'm not sure how much effort they put into trying to start them so you might be surprised when it arrives.

Alan


Sent from my iPhone using Tapatalk
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: AshimotoK0 on July 24, 2016, 01:36:05 PM
Welcome. What's not known on this site about our bikes isn't worth knowing!

I've bought two DK specials now. Pleased with both of them. My CL350 was described in exactly the same way, but after checking it over and putting a new battery in it started straight away and I rode up the road with it. I'm not sure how much effort they put into trying to start them so you might be surprised when it arrives.

Alan


Sent from my iPhone using Tapatalk

Don't know if you are aware Al but there is an M6 bolt on the cambox on the CB/CL350 twins. It's purpose is to check oil feed to the top end. Funnily,  only about four years ago,  I asked DK why they never imported smallish Honda Twins and they told me it wasn't worth it / No demand. They obviously had a rethink!I was really pleased with the the '69 350K1 I got from them. They had removed bits from it and it never sold so I picked it up in a 'deal'  for less than £1K but it had the nicest chrome of any other twin I have seen them selling. I literally had nothing to re-chrome on it.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Underdog1 on July 24, 2016, 02:51:05 PM
So the bikes just been delivered, cosmetically it looks in reasonable nick.

The first obvious issue is it didn't come with any keys, i presume theres some sort of way to order them through Honda?
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: MarkCR750 on July 24, 2016, 04:23:27 PM
You could Hotwire it for now, pul the plug out of the ignition switch and connect red to black, ages since I did mine, someone correct me if I'm wrong!
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Chris400F on July 24, 2016, 04:57:01 PM
Not sure about the 750 but on smaller models the key number is often marked on the body of the ignition switch somewhere.
I have used this guy a couple of times to order keys by number.
http://www.ebay.co.uk/itm/281030401159?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Underdog1 on July 24, 2016, 05:05:32 PM
You could Hotwire it for now, pul the plug out of the ignition switch and connect red to black, ages since I did mine, someone correct me if I'm wrong!

Yeah ill give that a go for now, cheers bud.

Not sure about the 750 but on smaller models the key number is often marked on the body of the ignition switch somewhere.
I have used this guy a couple of times to order keys by number.
http://www.ebay.co.uk/itm/281030401159?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

The only code i can find is on the seat lock, I've messaged the seller and hopefully the seat lock is the same as the ignition.


Other things I've noted so far:

No front brake calliper! Bit annoying as looking on bey I'm going to be spending £80+ replacing it.. Does anyone know if I can use any CB750 SOHC calliper or do they differ year to year?

Inside of the tank is mega rusty. Going to try some electrolysis to see if i can bring it back to life.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Trigger on July 24, 2016, 06:23:29 PM
Let the fun begin  ::) Not all SOHC calipers are the same, don't rush as you will need to get the old girl running before worrying about getting her to stop.
The seat key is very rarely the same as the ignition. 
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Spitfire on July 24, 2016, 07:58:40 PM
This might help finding a caliper.
http://www.sohc.co.uk/index.php/topic,1562.0.html

Cheers

Dennis
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Trigger on July 24, 2016, 08:09:57 PM
Bought a CB750 with a CB550 disc fitted once from DK, loads of fun trying to work that one out.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Chris400F on July 24, 2016, 09:17:44 PM
The seat key is very rarely the same as the ignition.
Is the key number likely to be marked on the ignition switch, and if so where should our friend be looking?
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Trigger on July 24, 2016, 09:30:52 PM
If it is a original ignition, it will be on the face and start with T and then 4 numbers. If a later or repro it will be on the barrel 
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Underdog1 on July 24, 2016, 10:33:37 PM
Let the fun begin  ::) Not all SOHC calipers are the same, don't rush as you will need to get the old girl running before worrying about getting her to stop.
The seat key is very rarely the same as the ignition.

Ahh. Well I've ordered one from eBay, it was only £6 so worth a shot I suppose. Will get the ignition barrel out tomorrow and have a deeper look
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Rob.b (Rob Birkett - RIP) on July 25, 2016, 10:04:15 AM
Hi.
Have a look on Youtube for vids by 'hackaweek' called
"73 honda CB750 cafe racer rebuild "
I am enjoying watching all thirty odd episodes and I don't even own a CB750.

Enjoy Rob.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Trigger on July 25, 2016, 06:59:36 PM
I build all SOHC engines for a living and the guy is a muppet, build a engine hanging up side down ???
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: AshimotoK0 on July 25, 2016, 07:52:28 PM
I build all SOHC engines for a living and the guy is a muppet, build a engine hanging up side down ???

He is 'Dino'  ... He's a member on the US site and receives quite a bit of praise from members there. Certainly has a wide diversity of projects inc electronics bikes etc.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Trigger on July 25, 2016, 08:17:25 PM
I build all SOHC engines for a living and the guy is a muppet, build a engine hanging up side down ???

He is 'Dino'  ... He's a member on the US site and receives quite a bit of praise from members there. Certainly has a wide diversity of projects inc electronics bikes etc.
 

Electric bike  ??? that explains everything. So, are you going to take his advise and replace all the con rod nuts and bolts ;) ;)
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: AshimotoK0 on July 25, 2016, 08:23:18 PM
I build all SOHC engines for a living and the guy is a muppet, build a engine hanging up side down ???

He is 'Dino'  ... He's a member on the US site and receives quite a bit of praise from members there. Certainly has a wide diversity of projects inc electronics bikes etc.
 

Electric bike  ??? that explains everything. So, are you going to take his advise and replace all the con rod nuts and bolts ;) ;)

No 'cos 3 people on here told me I don't need too. Yea  some of the things he does make me cringe a lot but  until you do your video teach-in Graham, it's about the best we have !  Sorry I meant electronic projects & bike projects etc.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Nurse Julie on July 25, 2016, 08:41:33 PM
I build all SOHC engines for a living and the guy is a muppet, build a engine hanging up side down ???

He is 'Dino'  ... He's a member on the US site and receives quite a bit of praise from members there. Certainly has a wide diversity of projects inc electronics bikes etc.
 

Electric bike  ??? that explains everything. So, are you going to take his advise and replace all the con rod nuts and bolts ;) ;)

No 'cos 3 people on here told me I don't need too. Yea  some of the things he does make me cringe a lot but  until you do your video teach-in Graham, it's about the best we have !  Sorry I meant electronic projects & bike projects etc.
I have just watched Part 14 of that series. I'm sure he is a very nice man but, what a plank. If it took Graham that long to build his SOHC engines, he would go out of business. And what's the idea of building it upside down?, surely gravity is working against him, how weird 😃😃😃
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Rob.b (Rob Birkett - RIP) on July 25, 2016, 09:06:13 PM
Hi.
Have a look on Youtube for vids by 'hackaweek' called
"73 honda CB750 cafe racer rebuild "
I am enjoying watching all thirty odd episodes and I don't even own a CB750.

Enjoy Rob.


Underdog,  I'm so sorry,  I seem to have inadvertently thrown a metaphorical spanner into your thread, now it's all about that fella on Youtube. Is he Australian Perhaps; and could that be why he builds engines upside down.  8)

I'm new here myself, but from what I've read.on this excellent forum I feel sure that you are eventually going to find all the information and help you could ever want.

Rob
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Nurse Julie on July 25, 2016, 09:18:16 PM
Rob. Threads go off track all the time on this forum, it's all part of the fun of it but, eventually all questions are answered and problems solved just via a somewhat convoluted route.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Rob.b (Rob Birkett - RIP) on July 25, 2016, 09:47:10 PM
Rob. Threads go off track all the time on this forum, it's all part of the fun of it but, eventually all questions are answered and problems solved just via a somewhat convoluted route.

Hello Julie,  yeah I know, I've spent ages reading this site since I joined it's GR8.

Now I'm going to have to jump to part 14 to see just why he builds engines upside down. Cos right now I can't even understand how it's even possible, does he keep everything in place with Honda bond  just before he 'sungs it up'.  Ho ho

R
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Nurse Julie on July 25, 2016, 09:52:47 PM
More like fingers crossed and a prayer by the looks of it Rob  ;D ;D
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Underdog1 on July 25, 2016, 09:57:13 PM
This might help finding a caliper.
http://www.sohc.co.uk/index.php/topic,1562.0.html

Cheers

Dennis

Yeah that may well come in handy, cheers bud!

Underdog,  I'm so sorry,  I seem to have inadvertently thrown a metaphorical spanner into your thread, now it's all about that fella on Youtube. Is he Australian Perhaps; and could that be why he builds engines upside down.  8)

I'm new here myself, but from what I've read.on this excellent forum I feel sure that you are eventually going to find all the information and help you could ever want.

Rob

Hah no worries!



So i only managed to get 30 minutes or so poking about the old girl today as i finished work late. Took the ignition off at the block connector, connected a good battery touched the spade connectors for the red and black wires and didn't get anything.. no electrics.

(https://s31.postimg.org/ixk840cm3/IMG_0158.jpg)

Hopefully this is a fault at my end as the advert did state that the bike turned over with a good battery, is there a better way to bypass the ignition?

Now I've got the lock off anyone know a way i can find the key code (on I'm assuming the lock barrel) without destroying it?).

(https://s31.postimg.org/j1e1k9i3f/IMG_0160.jpg)

Now the tanks off I'm a little confused by the fuel line set up.. the petcock has 2 outlets but i can only see one fuel line fitted (nothing was actually connected up though) which has a T junction to seemingly feed a each pair of carbs. So this set up means all the carbs are fed off just one petcock outlet.. I'm probably being an idiot here but whats the other petcock outlet for?  ;D

(https://s31.postimg.org/3nkcwth3v/IMG_0157.jpg)
(https://s31.postimg.org/gdol9wp23/IMG_0156.jpg)

As a bonus, heres the inside of my petrol tank the dirty old girl

(https://s31.postimg.org/kf5ofkhcr/IMG_0159.jpg)
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: K2-K6 on July 25, 2016, 09:59:42 PM
Well I've never seen one built like that before i. e. upside down, seems like he's creating more problems than he's trying to solve. Maybe he can't put the barrels down onto already installed pistons and rods because he's had to cut away the bottom of them to clear the massive alloy rods and lost the taper to help lead the rings into the barrels.

The rods don't even look finished properly with some really big stress raisers built in for good measure, surely if you are going to run an alternative you'd want a better quality than standard.

And he kept rattling those exposed big end bolts against the crank journals!!!  if you drop the rods down onto the crank on a car engine, you'd place something like silicon hose over the threads to avoid contact with the crank.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Underdog1 on July 26, 2016, 11:14:22 AM
Another quick question, and inknow this can be a contentious issue...

Is running a 10w40 Semi synthetic oil API SL/CF ok for this bike?
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Trigger on July 26, 2016, 01:13:43 PM
It is not contentious, you need 10-40 mineral. The ignition should have a plug on it that plugs into the loom.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: royhall on July 26, 2016, 01:14:37 PM
Not seen that video for a while but from memory, I think he does it that way so he can fit one piston at a time instead of having to deal with all four. In avoiding that one small issue he creates many more issues. Really weird way of doing it.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Trigger on July 26, 2016, 01:19:43 PM
Not seen that video for a while but from memory, I think he does it that way so he can fit one piston at a time instead of having to deal with all four. In avoiding that one small issue he creates many more issues. Really weird way of doing it.

I have never seen so many school boy errors.
Title: CB750 Barn find project - Where do i even start!?
Post by: JamesH on July 26, 2016, 04:57:20 PM
This might help finding a caliper.
http://www.sohc.co.uk/index.php/topic,1562.0.html

Cheers

Dennis

Yeah that may well come in handy, cheers bud!

Underdog,  I'm so sorry,  I seem to have inadvertently thrown a metaphorical spanner into your thread, now it's all about that fella on Youtube. Is he Australian Perhaps; and could that be why he builds engines upside down.  8)

I'm new here myself, but from what I've read.on this excellent forum I feel sure that you are eventually going to find all the information and help you could ever want.

Rob

Hah no worries!



So i only managed to get 30 minutes or so poking about the old girl today as i finished work late. Took the ignition off at the block connector, connected a good battery touched the spade connectors for the red and black wires and didn't get anything.. no electrics.

(https://s31.postimg.org/ixk840cm3/IMG_0158.jpg)

Hopefully this is a fault at my end as the advert did state that the bike turned over with a good battery, is there a better way to bypass the ignition?

Now I've got the lock off anyone know a way i can find the key code (on I'm assuming the lock barrel) without destroying it?).

(https://s31.postimg.org/j1e1k9i3f/IMG_0160.jpg)

Now the tanks off I'm a little confused by the fuel line set up.. the petcock has 2 outlets but i can only see one fuel line fitted (nothing was actually connected up though) which has a T junction to seemingly feed a each pair of carbs. So this set up means all the carbs are fed off just one petcock outlet.. I'm probably being an idiot here but whats the other petcock outlet for?  ;D

(https://s31.postimg.org/3nkcwth3v/IMG_0157.jpg)
(https://s31.postimg.org/gdol9wp23/IMG_0156.jpg)

As a bonus, heres the inside of my petrol tank the dirty old girl

(https://s31.postimg.org/kf5ofkhcr/IMG_0159.jpg)
Good news is the carbs are probably original to the bike. The K5/6 US models switched the petcock (fuel tap) to the LHS with a single fuel outlet. They did this as a safety update so if a rider hit reserve they could switch the tap with the left (non throttle) hand.

Looks like you have a K2 tank and seat fitted. The K2 tank has the fuel tap (with two outlets) on the RHS.

Given the rusty fuel tank, get yourself one of these so you don't contaminate the carbs (once you've checked and cleaned them) when you first run the bike after basic inspection / servicing..:

https://www.ebay.co.uk/itm/351510130564

I've recommissioned several US import 750's and they are generally pretty bullet-proof. Do yourself a favour and get her running nicely first before you start spending out too much...

James
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Underdog1 on July 26, 2016, 05:30:54 PM
Looks like you have a K2 tank and seat fitted. The K2 tank has the fuel tap (with two outlets) on the RHS.

Given the rusty fuel tank, get yourself one of these so you don't contaminate the carbs (once you've checked and cleaned them) when you first run the bike after basic inspection / servicing..:

https://www.ebay.co.uk/itm/351510130564

I've recommissioned several US import 750's and they are generally pretty bullet-proof. Do yourself a favour and get her running nicely first before you start spending out too much...

James

Ah that would explain it, i take it i can just run two fuel lines from it (one to each pair of carbs)?

Just bought that remote fuel tank, was literally about to bodge one together out of an old petrol can and hosepipe  ;D

Started work on cleaning the rust out the tank

(https://s32.postimg.org/c1oenjs8l/IMG_0163.jpg)

Gwarn science lad!
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Underdog1 on July 27, 2016, 11:54:57 AM
No real progress so far, the key i ordered still hasn't turned up and i haven't been able to get the ignition on by using a decent battery and connecting the red and black ignition wires.

Wish i had just bought an aftermarket ignition and key as it would have been the same price and would be here by now!

The 40 year old wiring looks crusty and a lot of the connectors look well past there prime, i think I'm going to rewire the entire bike at some point as it looks like the wiring can be simplified a bit and will at least last a while then.

I found this schematic online, is this a good place to start?

(https://s31.postimg.org/piipev9uz/SOHC750wiring_jpg_thumb.png)
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: AshimotoK0 on July 27, 2016, 12:15:59 PM
Looks OK ..no horn or indicators though. If I was doing a non-standard rewire I think I would use sealed Deutsch connectors for perfect weather protection
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Underdog1 on July 27, 2016, 01:29:48 PM
yeah I'm going to do away with indicators, no time for that nonsense.

Will look up those connectors you mentioned.

As I'm waiting out on this key to arrive I'm just familiarising myself with the bike. Came across this tube which looks to be some sort of breather or overflow tube. Not quite sure what its for though.

Top end is near the battery

(https://s31.postimg.org/x99acvpdn/IMG_0167.jpg)

Other end comes out next to the centre stand

(https://s31.postimg.org/5zxwydoaj/IMG_0168.jpg)
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: AshimotoK0 on July 27, 2016, 02:09:40 PM
I may have some of those connectors somewhere,  if I can find any I will dig a few  out for you (free) . Good thing is you can solder them  as well as crimp. I have the hand crimper in the loft somewhere ...today that tool costs over 350 quid!


[attachimg=1]

[attachimg=2]
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: JamesH on July 27, 2016, 02:38:41 PM
Looks like you have a K2 tank and seat fitted. The K2 tank has the fuel tap (with two outlets) on the RHS.

Given the rusty fuel tank, get yourself one of these so you don't contaminate the carbs (once you've checked and cleaned them) when you first run the bike after basic inspection / servicing..:

https://www.ebay.co.uk/itm/351510130564

I've recommissioned several US import 750's and they are generally pretty bullet-proof. Do yourself a favour and get her running nicely first before you start spending out too much...

James

Ah that would explain it, i take it i can just run two fuel lines from it (one to each pair of carbs)?

Just bought that remote fuel tank, was literally about to bodge one together out of an old petrol can and hosepipe  ;D

Started work on cleaning the rust out the tank

(https://s32.postimg.org/c1oenjs8l/IMG_0163.jpg)

Gwarn science lad!

Yeah - just run a pair of individual lines and you'll be fine.

That overflow tube by the battery tray is for the battery overflow (for lead-acid batteries). If you use a sealed / agm battery you can do away with it.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Underdog1 on July 27, 2016, 04:30:12 PM
I may have some of those connectors somewhere,  if I can find any I will dig a few  out for you (free) . Good thing is you can solder them  as well as crimp. I have the hand crimper in the loft somewhere ...today that tool costs over 350 quid!


(Attachment Link)

(Attachment Link)

That would be awesome, cheers bud!
Yeah - just run a pair of individual lines and you'll be fine.

That overflow tube by the battery tray is for the battery overflow (for lead-acid batteries). If you use a sealed / agm battery you can do away with it.

Yeah took the rear fender off and there was a little sticker underneath with a diagram of it  :D
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Underdog1 on July 28, 2016, 01:14:32 PM
So another day and the replacement keys still haven't turned up! The doubt the set i ordered from the code on the tank lock are even going to fit now as (a previous poster alluded to) the ignition should have a code on it somewhere unless it is aftermarket.. and i can't find one. Called a local locksmith and he quoted me some silly price to cut a key so I've just ordered an aftermarket ignition and key from eBay. If it turns out the set of keys I've ordered do fir then i can just return it i suppose.

So with not really much else i can do right now I've looked at the tank this morning, its been on the electric chair for over 2 days and I've conditionally ben scraping all sorts off the sacrificial anode so its definitely done something. I emptied it out sprayed some WD40 inside and swilled it out with methylated spirt before drying it out with a hair drier.

Suprisingy it doesn't actually look any better than before despite the crap that came out of it

(https://s31.postimg.org/647t8dfnf/IMG_0182.jpg)

and after looking deeper inside with a torch i found what looks like some sort of old sealant inside towards the front end of the tank

(https://s31.postimg.org/jz63qua2j/IMG_0184.jpg)
(https://s31.postimg.org/pbuy4yxyz/IMG_0185.jpg)

so with my best screwdriver i tried to scrape it off and found it to be quite hard

(https://s31.postimg.org/e0saglr3v/IMG_0188.jpg)

only managed to get a small bit out

(https://s31.postimg.org/44r7gylbv/IMG_0189.jpg)
(https://s31.postimg.org/a6yu7g9rv/IMG_0190.jpg)

Any tips on how i can strip all this shite out? Its probably the reason why the electrolysis didn't work as well as i thought it would
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: JamesH on July 28, 2016, 01:17:45 PM
Order some MEK (Methyl Ether Ketone) which is an industrial solvent. It will eat the sealer (and any paint so be careful if you want to preserve the paint).
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Underdog1 on July 28, 2016, 01:48:08 PM
Order some MEK (Methyl Ether Ketone) which is an industrial solvent. It will eat the sealer (and any paint so be careful if you want to preserve the paint).

Cool,have heard that mentioned alongside acetone as good for cleaning out tanks.

Is there an established method for using MEK? I.e. do you ust swill a few litres about or dilute it and brim the tank to leave overnight etc?
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: JamesH on July 28, 2016, 02:39:57 PM
I used it neat on a tank with a Kreeme liner. Left it in for a couple of hours, swilled every 30 mins and then drained through a coffee filter for re-use. You may want to de-grease the tank first so the MEK can get straight on to dissolving the liner without a grease barrier to deal with.
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: Underdog1 on July 28, 2016, 02:43:40 PM
I used it neat on a tank with a Kreeme liner. Left it in for a couple of hours, swilled every 30 mins and then drained through a coffee filter for re-use. You may want to de-grease the tank first so the MEK can get straight on to dissolving the liner without a grease barrier to deal with.

Thanks for the info, although that does mean I'm going to need 18 litres of the bloody stuff!
Title: Re: CB750 Barn find project - Where do i even start!?
Post by: tom400f on July 28, 2016, 03:00:50 PM
Notwithstanding all the above cleaning and prep, once you get past that you might consider finishing the inside like this: http://www.sohc.co.uk/index.php/topic,4758.0.html

You can also seal small holes with that stuff. The kit I used comes with a small amount of webbing that (I guess) you submerge in the paint in the affected area though this wasn't required in my case.

Not original, obviously, but as a rust solution it works very well.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 28, 2016, 08:48:47 PM
Just stripped the back end down today and cleaned a few bits up, nothing really noteworthy.

Anyone know what this little nipple bit on the swingarm is for?

(https://s32.postimg.org/sh69n0o1h/Full_Size_Render.jpg)

Also theres some little bracket down near the centre stand which doesn't seem to be doing anything, is this for a stand sensor or something?

(https://s32.postimg.org/54884i7xx/IMG_0197.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: JamesH on July 28, 2016, 08:50:47 PM
That's the grease nipple for the swingarm pivot assy. Bracket is unique to K6 and acts as a hose guide - can't remember which hose..
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 28, 2016, 09:09:24 PM
That's the grease nipple for the swingarm pivot assy. Bracket is unique to K6 and acts as a hose guide - can't remember which hose..

ah ideal, thinking about it its probably for the battery breather which i yanked out yesterday  8)
Title: Re: CB750 Barn find project - First Timer
Post by: JamesH on July 28, 2016, 09:10:14 PM
You should invest in a copy of Hondaman's book...brilliant informative read...
Title: Re: CB750 Barn find project - First Timer
Post by: tom400f on July 28, 2016, 09:26:48 PM
The hole in the stand is a guide for a tube of some sort. Rocker breather or perhaps the lead acid battery overflow
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on July 28, 2016, 09:44:07 PM
It is for the battery overflow and is black rubber.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 28, 2016, 11:34:34 PM
Thanks for the answers chaps.

Is it best to go oem for things like bushes and bearing or are there better alternatives?

Seen some recommendations for bronze swingers bushes and seen these on fleabay:

http://www.ebay.co.uk/itm/Swing-Arm-Bearing-swing-arm-bushes-bronze-bushes-2005180045061-/282021721757?hash=item41a9cdf69d:g:IYEAAOSwKfVXJBTE

literally a quarter of the price of the OEM ones from david silver, but I'm not one to waste money on crap even if it is cheap crap.
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on July 29, 2016, 02:51:51 AM
Thanks for the answers chaps.

Is it best to go oem for things like bushes and bearing or are there better alternatives?

Seen some recommendations for bronze swingers bushes and seen these on fleabay:

http://www.ebay.co.uk/itm/Swing-Arm-Bearing-swing-arm-bushes-bronze-bushes-2005180045061-/282021721757?hash=item41a9cdf69d:g:IYEAAOSwKfVXJBTE

literally a quarter of the price of the OEM ones from david silver, but I'm not one to waste money on crap even if it is cheap crap.

Try Frank, have fitted more than 50 sets of these and many members use him >>> http://www.ebay.co.uk/itm/131207862914?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on July 29, 2016, 06:39:19 AM
The collar is frequently more worn than the bushes and costs even more
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 29, 2016, 03:58:58 PM
The collar is frequently more worn than the bushes and costs even more

The collar? mine look like top hats and are one piece

(https://s31.postimg.org/ebmtkd8wb/IMG_0209.jpg)

Managed to get a quick bit of time on the bike in today, just stripped down the front and rear brakes, attempted to remove the rear wheel bearing (didn't realise i needed a special tool) and just cleaned a few bits
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on July 29, 2016, 07:10:31 PM
The collar is the steel bit that the bushes pivot on mate NOTE:- NOT the bolt that goes through the inside of the collar ( I call it a pivot but Honda call it a collar)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 29, 2016, 08:40:59 PM
The collar is the steel bit that the bushes pivot on mate NOTE:- NOT the bolt that goes through the inside of the collar ( I call it a pivot but Honda call it a collar)

Do you mean number 9 in this diagram?

(http://images.cmsnl.com/img/partslists/honda-cb750k-750-four-k-1976-usa-swingarmdrive-chain_bighu0027f1619_1eec.gif)

Is there anything i should check for specifically to see if its worn beyond the point of reuse?
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on July 29, 2016, 10:42:23 PM
Yup, but I think you have to use the earlier (K1,2,3) one as the later one is NLA
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 30, 2016, 12:50:48 PM
Yup, but I think you have to use the earlier (K1,2,3) one as the later one is NLA

just checked mine over and it looks hardly worn at all so probably going to stick with it.

Looking forward to the future i intend on doing away with the tacho and just having a speedo, I've seen the speedo centre mounted before and it just looks a little..big.

(https://s32.postimg.org/occjppn6t/CB750_LREdits5of12_1600x1067.jpg)

I love the styling of these old speedos though and don't want to buy anything new. Does anyone know of any bikes similar looking speedos that are a bit smaller?
Title: Re: CB750 Barn find project - First Timer
Post by: mickwinf on July 30, 2016, 01:42:38 PM
500 fours and 250/350 use smaller versions.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 30, 2016, 03:27:04 PM
500 fours and 250/350 use smaller versions.

Perfect.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 30, 2016, 03:32:57 PM
So being the tight arse that i am i made my own bearing retainer removal tool today

(https://s31.postimg.org/a9bi7814p/IMG_0217.jpg)

Worked pretty well.

(https://s31.postimg.org/z1b4egibf/IMG_0216.jpg)

Didn't get long to work with the bike, didn't manage to get either wheel bearing out, should they just slide out each side at this point or do i need to be pushing them through and out the other side? My haynes manual just states that at this point the bearing can be removed. Might be a case or trying to yank them out with a screwdriver i suppose.

The threads on the bearing retainer look mega delicate being very fine aluminium, is this something that is usually replaced when changing wheel bearings?

Current state:

(https://s31.postimg.org/qzrhaaoxn/IMG_0218.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Chris400F on July 30, 2016, 05:12:27 PM
500 fours and 250/350 use smaller versions.
Do they all have the same 'ratio'? I believe some tachos differ between models; I had a couple with different ratios printed on the back of the casings.
Note also that 250/350/360 twins and 350/400 fours have 18" front wheels while 500 and above have 19", may also affect your choice.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 30, 2016, 09:37:20 PM
500 fours and 250/350 use smaller versions.
Do they all have the same 'ratio'? I believe some tachos differ between models; I had a couple with different ratios printed on the back of the casings.
Note also that 250/350/360 twins and 350/400 fours have 18" front wheels while 500 and above have 19", may also affect your choice.

Ok cool that's given me something to consider, although I doubt an inch difference in diameter is going to affect things massively as its only roughly 5% difference in running circumference. I'm sure these speedos are pretty inaccurate anyway #maths
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 01, 2016, 02:34:07 PM
Oooookay,

So a few bits arrived in the post today, my replacement ignition and remote tank which got me a little excited as finally i can see if this thing starts right?

So first thing i notice is in key position 1 i seem to have power, the neutral light comes on, if i press the horn i get a very weak sounding fart noise,no headlight and unfortunately I've already stripped off the brakes and rear light so can't check those right now. Key position 2 the neutral light goes out and the horn ceases to work so somethings going on there. The connectors that go into the ignition connector block short with each other mega easily but i made sure they weren't touching each other and still no luck. Electric start also didn't do anything.

Anyway i thought its worth trying to kick it anyway to see what happens, plumbed in my remote tank (credit to Jamesh_sussex for the link) and fuel just immediately pissed out of carb 1&2 from the areas circled. Haven't got my haynes manual to hand so apologies for the lack of technical terms (and knowledge hah).

(https://s32.postimg.org/7n8e9i9l1/IMG_0229.jpg)

is this likely to be stuck floats? Was hoping i could see if it would run first before rebuilding the carbs but looks like this is going to be my next job. Just want to hear the old gal growl  :-[
Title: Re: CB750 Barn find project - First Timer
Post by: Rob.b (Rob Birkett - RIP) on August 01, 2016, 03:11:33 PM
Oooookay,

So a few bits arrived in the post today, my replacement ignition and remote tank which got me a little excited as finally i can see if this thing starts right?

So first thing i notice is in key position 1 i seem to have power, the neutral light comes on, if i press the horn i get a very weak sounding fart noise,no headlight and unfortunately I've already stripped off the brakes and rear light so can't check those right now. Key position 2 the neutral light goes out and the horn ceases to work so somethings going on there. The connectors that go into the ignition connector block short with each other mega easily but i made sure they weren't touching each other and still no luck. Electric start also didn't do anything.

Anyway i thought its worth trying to kick it anyway to see what happens, plumbed in my remote tank (credit to Jamesh_sussex for the link) and fuel just immediately pissed out of carb 1&2 from the areas circled. Haven't got my haynes manual to hand so apologies for the lack of technical terms (and knowledge hah).

is this likely to be stuck floats? Was hoping i could see if it would run first before rebuilding the carbs but looks like this is going to be my next job. Just want to hear the old gal growl  :-[

Hi,

I'm pretty sure position 2 on the ignition switch is the parking lights ie. the front pilot light and rear tail light only, and nothing else..

if so you should be able to take the key out when its in position 2.

keep at it.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 01, 2016, 04:47:59 PM
Oooookay,

So a few bits arrived in the post today, my replacement ignition and remote tank which got me a little excited as finally i can see if this thing starts right?

So first thing i notice is in key position 1 i seem to have power, the neutral light comes on, if i press the horn i get a very weak sounding fart noise,no headlight and unfortunately I've already stripped off the brakes and rear light so can't check those right now. Key position 2 the neutral light goes out and the horn ceases to work so somethings going on there. The connectors that go into the ignition connector block short with each other mega easily but i made sure they weren't touching each other and still no luck. Electric start also didn't do anything.

Anyway i thought its worth trying to kick it anyway to see what happens, plumbed in my remote tank (credit to Jamesh_sussex for the link) and fuel just immediately pissed out of carb 1&2 from the areas circled. Haven't got my haynes manual to hand so apologies for the lack of technical terms (and knowledge hah).

is this likely to be stuck floats? Was hoping i could see if it would run first before rebuilding the carbs but looks like this is going to be my next job. Just want to hear the old gal growl  :-[

Hi,

I'm pretty sure position 2 on the ignition switch is the parking lights ie. the front pilot light and rear tail light only, and nothing else..

if so you should be able to take the key out when its in position 2.

keep at it.

Yeah you're correctomundo, realised shortly after i posted  ::)

Any idea how i get the bearing retainer off this side of the wheel hub?

(https://s31.postimg.org/4xdt7w4a3/IMG_0231.jpg)

Managed to get the other side off with a home made tool but not sure about this side..
Title: Re: CB750 Barn find project - First Timer
Post by: hairygit on August 01, 2016, 04:58:20 PM
There isn't one on the wheel that side, just a thick oil/grease seal. Try levering it out with a tyre lever or large screwdriver, a little at a time on opposite edges at a time. Try not to gouge the alloy of the hub as you do it. Or you can use the bearing to remove it by knocking it through from the other side.
Title: Re: CB750 Barn find project - First Timer
Post by: MarkCR750 on August 01, 2016, 04:59:11 PM
Yes stuck floats, take the carbs off, take the float and float needle valve and jets out of carb no1 , the primary jet is pressed in, gently pull out with pliers, thoroughly blast out the passage ways and components with good quality carb cleaner, check the float needle seats for damage, check the black rubber tips on the float needles aren't worn, replace and do the same on the other 3 carbs, or send the carb bank off the NRP to have them ultrasonically cleaned and any worn components replaced, I did my own and they are fine but it's always down to personal choice and pocket.

http://nrp-carbs.co.uk/
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 01, 2016, 07:52:42 PM
There isn't one on the wheel that side, just a thick oil/grease seal. Try levering it out with a tyre lever or large screwdriver, a little at a time on opposite edges at a time. Try not to gouge the alloy of the hub as you do it. Or you can use the bearing to remove it by knocking it through from the other side.

Are you sure about that? I think its no. 4 on this picture in my haynes manual:

(https://s32.postimg.org/covq60ol1/Full_Size_Render.jpg)

Title: Re: CB750 Barn find project - First Timer
Post by: hairygit on August 01, 2016, 08:46:49 PM
Did you remove a retainer from the wheel itself, or from the separate sprocket carrier. Racking my brain here, and only recall 1 retainer on the wheel itself, plus a second larger one on the sprocket carrier.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 01, 2016, 10:16:20 PM
Did you remove a retainer from the wheel itself, or from the separate sprocket carrier. Racking my brain here, and only recall 1 retainer on the wheel itself, plus a second larger one on the sprocket carrier.

Ive removed one from the sprocket carrier (no.3 in the pic) and the one remaining is in the wheel hub (no.4 in the pic). I think i even confused myself on that one haha.

For the card rebuild should i be ordering one of these for each carb:

https://www.davidsilverspares.co.uk/CB750K6-FOUR-1976/part_105211/

or will there only be specific things ill need to replace depending what i find on inspection?
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on August 01, 2016, 10:27:05 PM
How much ? same set and you get all 4 >>http://www.ebay.co.uk/itm/Honda-CB750K-K1-K2-K3-K4-K5-K6-Carb-Repair-Kits-4-Repair-Kits-Include-48-1912-/261752454445?hash=item3cf1a97d2d   ;)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 02, 2016, 09:07:42 AM
How much ? same set and you get all 4 >>http://www.ebay.co.uk/itm/Honda-CB750K-K1-K2-K3-K4-K5-K6-Carb-Repair-Kits-4-Repair-Kits-Include-48-1912-/261752454445?hash=item3cf1a97d2d   ;)

Thats much more reasonable, is there much difference in quality in these rebuild kits or should I be fine with the eBay unbranded one?
Title: Re: CB750 Barn find project - First Timer
Post by: Rob.b (Rob Birkett - RIP) on August 02, 2016, 09:30:10 AM
How much ? same set and you get all 4 >>http://www.ebay.co.uk/itm/Honda-CB750K-K1-K2-K3-K4-K5-K6-Carb-Repair-Kits-4-Repair-Kits-Include-48-1912-/261752454445?hash=item3cf1a97d2d   ;)

Thats much more reasonable, is there much difference in quality in these rebuild kits or should I be fine with the eBay unbranded one?

Morning.

I have been hanging round this site a lot of late, and I think that I have learned; if Trigger says buy something you should buy it !!

But I still recommend you watch: hackaweek "73 honda CB750 cafe racer rebuild " on Youtube.

R
Title: Re: CB750 Barn find project - First Timer
Post by: Chris400F on August 02, 2016, 09:48:01 AM
How much ? same set and you get all 4 >>http://www.ebay.co.uk/itm/Honda-CB750K-K1-K2-K3-K4-K5-K6-Carb-Repair-Kits-4-Repair-Kits-Include-48-1912-/261752454445?hash=item3cf1a97d2d   ;)

Thats much more reasonable, is there much difference in quality in these rebuild kits or should I be fine with the eBay unbranded one?
There are loads of people on here (myself included) who have used the Cruzinimage kits as in Trigger's link and they are fine.
As Rob says, if Trigger recommends something you will be OK!
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 02, 2016, 10:24:00 AM
Morning.

I have been hanging round this site a lot of late, and I think that I have learned; if Trigger says buy something you should buy it !!

But I still recommend you watch: hackaweek "73 honda CB750 cafe racer rebuild " on Youtube.

R

Yeah watched the first two episodes and couldn't stand the bloke hah


There are loads of people on here (myself included) who have used the Cruzinimage kits as in Trigger's link and they are fine.
As Rob says, if Trigger recommends something you will be OK!

Cheers boys  ;D
Title: Re: CB750 Barn find project - First Timer
Post by: AshimotoK0 on August 02, 2016, 10:37:02 AM
Personally, the only aftermarket carb kits I will use are from Yamiya or kits like Gerben in Holland  sells.. Don't get me wrong there could be nothing wrong with other carb kits but they also sell inlet rubber kits and camchain rubber idlers that I know to be inferior to OEM and causing people on the US site horrendous problems. Gerben has the right idea ..he sells the 'O' ring kits sourced in Viton. He's got a really good reputation for rebuilding carbs. Rubber compounding is a science in itself. I worked for a company for 20 years that were experts in it, so I feel qualified to comment. DS will not tell me who he sources his aftermarket rubber parts from or give tech specs to check for myself, so again I have voted with my feet on that one.

http://www.ebay.co.uk/itm/CB500-CB550-4-Four-Keihin-carb-O-ring-set-VITON-rubber-for-4-carbs-/112047503140?hash=item1a168d3724:m:ms0_u4ZL-QLjaYiVzIQED2w

Dunno if he does kits  for 750

[attachimg=1]

Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 02, 2016, 06:57:16 PM
Personally, the only aftermarket carb kits I will use are from Yamiya or kits like Gerben in Holland  sells.. Don't get me wrong there could be nothing wrong with other carb kits but they also sell inlet rubber kits and camchain rubber idlers that I know to be inferior to OEM and causing people on the US site horrendous problems. Gerben has the right idea ..he sells the 'O' ring kits sourced in Viton. He's got a really good reputation for rebuilding carbs. Rubber compounding is a science in itself. I worked for a company for 20 years that were experts in it, so I feel qualified to comment. DS will not tell me who he sources his aftermarket rubber parts from or give tech specs to check for myself, so again I have voted with my feet on that one.

http://www.ebay.co.uk/itm/CB500-CB550-4-Four-Keihin-carb-O-ring-set-VITON-rubber-for-4-carbs-/112047503140?hash=item1a168d3724:m:ms0_u4ZL-QLjaYiVzIQED2w

Dunno if he does kits  for 750

(Attachment Link)
Thanks for the link but already ordered the other kit mate.

Im still searching for a reasonably priced front caliper + all the mounting gear. Little confused as I've seen different types of mounts listed on the bay for my bike (76), some look like this (and so does the schematic in my haynes manual:

(http://i.ebayimg.com/images/g/hVoAAOSwGXtXhSLY/s-l1600.jpg)

and others look like this:

(http://i.ebayimg.com/images/g/XuAAAOSwAvJW~J9U/s-l500.jpg)

The mounting point on my forks looks like this:

(https://s32.postimg.org/610jtcbw5/IMG_0236.jpg)

Which type do I need?
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on August 02, 2016, 07:46:44 PM
The first picture is for CB750 K0 to K2, you need the arm in the second picture to fit the later forks
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 03, 2016, 05:54:18 PM
The first picture is for CB750 K0 to K2, you need the arm in the second picture to fit the later forks

Cheers bro  :)

Right so today I've had the carbs off, the carb bowls were full of some horrendous gunk but after a good few hours work I've got them pretty spankers

(https://s31.postimg.org/n0o6aga2j/Full_Size_Render.jpg)

I took the floats, float valves, main jet and pilot jet out. Soaked everything in carb cleaner and gave it a good old scrub. Cleaned out the main body of the carbs lubed the sliders and reassembled.

The carbs were an absolute nightmare to get back on, overtime i got one side on it sort of pivoted and pulled the other side out. Ended up tapping one side on with a rubber mallet, tightening up the clamps then tapping the other side on.

Got my remote fuel tank hooked up and as soon as i opened the petcock petrol came pissing out of the same place as previous (i had no airbox on).

(https://s32.postimg.org/7n8e9i9l1/IMG_0229.jpg)

Mostly came out of carbs 1 & 2 but was still dribbling out of 3&4.

Any ideas?
Title: Re: CB750 Barn find project - First Timer
Post by: MarkCR750 on August 03, 2016, 08:21:02 PM
Did the float valves look ok?, did the little spring loaded pins in the float valves spring in and out?, did you check the float heights?, I found a good "how to" online for PD carbs which mine has, try googling for one for your earlier type carbs, next time you replace the carbs heat the rubbers up (carefully) with an electric hot air gun, they harden with age and are a pig to get on if not softened, the trouble is that because you don't know what previous owners have done it's going to be a bit trial and error, it's got to be a float related issue, here's another thought, do your floats float, they could be punctured and filling up with fuel, that stops them floating up as the bowl fills and stops them pressing on float valve via the arm to cut the fuel off.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 03, 2016, 09:12:13 PM
Did the float valves look ok?, did the little spring loaded pins in the float valves spring in and out?, did you check the float heights?, I found a good "how to" online for PD carbs which mine has, try googling for one for your earlier type carbs, next time you replace the carbs heat the rubbers up (carefully) with an electric hot air gun, they harden with age and are a pig to get on if not softened, the trouble is that because you don't know what previous owners have done it's going to be a bit trial and error, it's got to be a float related issue, here's another thought, do your floats float, they could be punctured and filling up with fuel, that stops them floating up as the bowl fills and stops them pressing on float valve via the arm to cut the fuel off.

Yeah that little nipple on the float valves all spring in and out as they should. I'm going to take them off again tomorrow and check what you've mentioned. I had all the floats in a bowl of hot soapy water at one point..and I don't remember them actually floating hah.

Any reason why fuel would come out of that hole and not the drainage pipes out of interest?
Title: Re: CB750 Barn find project - First Timer
Post by: MarkCR750 on August 04, 2016, 07:59:32 AM
I'm not that familiar with the type of carbs you have, the holes that you refer to are balance pipes that should only have air in them (I think!), I agree that you would expect to see the fuel coming out of the overflows first, try squirting carb cleaner down the holes and see where it comes out inside the carb, that might give you a clue, hopefully someone with better knowledge of your carb type will join the thread!.
PS if you swap a float from one of the non leaking carbs into one that is leaking and it fixes it you'll know it's the floats.
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on August 04, 2016, 10:08:07 AM
Looks like the brass pipe inside the float bowls leading out to the overflow pipes could be blocked.

If the float valves don't seal then the fuel will get out another hole other than intended route,  it's probably coming out of the main jet also if you could see it. Those holes you've pointed out are primary circuit or air bypass as far as I know.

If it runs into the engine in any sizeable quantity,  it can cause a hydraulic lock above a piston and the bend a con rod when you turn it over so you need to make sure the correct overflow route is clear. At the minimum it will dilute the engine oil if it runs though the bores.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 04, 2016, 06:17:18 PM
Aha progress!

had the carbs off again, blew all the airways with a compressor and plenty of carb cleaner, reassembled and i think i had the float valves in upside down! although i did reassemble how it was when i took it apart. Cheers previous owner.

Chucked the carbs back on the bike and used a hairdryer this time to soften up the rubbers which made it 100x easier. Tried to kick her over and didn't get anything, checked the battery and it was like 7v. Got a good battery to jump it off and still couldn't get her going and by this point i imagine i had flooded the plugs so i took the choke off and kicked her with a wide open throttle and she sprang into life!!

http://sendvid.com/mw9r6td9 - Vid of her running

Now she wouldn't idle but thats probably due to the carbs not being set up correctly and not having an airbox on but she ran as long as i kept her at about 2000rpm.

Not all good news as cylinder 2 didn't seem to be firing right as the downpipe was only slightly warm compared to the others being too hot to touch, and after i switched her off i could hear a hissing and drips of oil coming from the left hand engine cover.

(https://s31.postimg.org/n186lb2yj/IMG_0262.jpg)

What do you think the issue could be? I plan on pulling the engine apart but its good if i can't perhaps pre-empt possibilities by doing some research  :)

Overall a definite step in the right direction!
Title: Re: CB750 Barn find project - First Timer
Post by: MarkCR750 on August 04, 2016, 06:36:04 PM
Great news, put the air box on and it will tickover , makes a huge difference with it off, No2 is either not getting a spark or fuel, check the HT cap is firmly screwed to the HT lead first, if that doesn't work, swap the cap with one of the other caps, by actually unscrewing the caps and swapping them over, don't swap the leads,and see if the problem follows the cap, if that doesn't work check the plug is getting wet with fuel if it isn't you might have a blockage in the carb, but before anything else try with the airbox fitted, try holding revs at 5k and see if the pipe gets hot, if it does your primary jet is blocked on that carb, holding higher revs means it's running on the main jet, regarding the hissing god knows, is the breather in the top of the cylinder head clear?, pull the pipe off for now.
PS video link doesn't work, YouTube is more reliable.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 04, 2016, 09:28:30 PM
Great news, put the air box on and it will tickover , makes a huge difference with it off, No2 is either not getting a spark or fuel, check the HT cap is firmly screwed to the HT lead first, if that doesn't work, swap the cap with one of the other caps, by actually unscrewing the caps and swapping them over, don't swap the leads,and see if the problem follows the cap, if that doesn't work check the plug is getting wet with fuel if it isn't you might have a blockage in the carb, but before anything else try with the airbox fitted, try holding revs at 5k and see if the pipe gets hot, if it does your primary jet is blocked on that carb, holding higher revs means it's running on the main jet, regarding the hissing god knows, is the breather in the top of the cylinder head clear?, pull the pipe off for now.
PS video link doesn't work, YouTube is more reliable.

Good call on the breather, took a fair amount of compressed air through it until it finally spat a glob of something out. The hissing ceased after this. Couldn't actually get the airbox on! It didn't come fitted to the bike and it's like the plastic boots are too small to fit on the carbs, maybe it's just the ancient plastic. In going to go down the pod route (cue eye rolls) so not too fussed anyway. Checked the HT lead for cyl 2 and got a faint click when I pressed down hard on it and the cyclinder seemed to fire properly after that so I think it's just a dodgy cap.

Going to pull the engine out when I get a chance as I'm getting the frame powder coated, even though I'm inexperienced I'm up for opening the lump up and refreshing whatever needs doing to keep the old girl running for another 40 years. What are the typical things that need addressing?

Finally I did notice that the final drive spindle for the front sprocket was spinning when revving the bike in neutral - is this just due to there being no sprocket or chain attached or is it some sort of fault?

Cheers!
Title: Re: CB750 Barn find project - First Timer
Post by: MarkCR750 on August 04, 2016, 10:32:02 PM
If you are going to use pods you'll need bigger main jets, I've used 135's in mine with a 4 into 1 exhaust and the mixture was bang on when dynoed, also check out my thread "how to make pod filters work", (no roll eyes on this forum , it's a league of gentlemen!), spindle spinning in neutral is normal, regarding what's typical when stripping the engine?, it's totally down to the engines previous life, have a search around the threads on this forum and you'll get an idea of the problems you might face,  but you'll probably enter a world of pain, most do , I've rebuilt various engines over the years but when the time comes to rebuild mine I'm giving it to Trigger and paying for his expertise, the cost will be more than offset by me being able to spend my time out riding my other bikes and knowing the jobs been done perfectly (Trig you can knock a fiver off my bill for that 😄).
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 05, 2016, 09:23:49 AM
If you are going to use pods you'll need bigger main jets, I've used 135's in mine with a 4 into 1 exhaust and the mixture was bang on when dynoed, also check out my thread "how to make pod filters work", (no roll eyes on this forum , it's a league of gentlemen!), spindle spinning in neutral is normal, regarding what's typical when stripping the engine?, it's totally down to the engines previous life, have a search around the threads on this forum and you'll get an idea of the problems you might face,  but you'll probably enter a world of pain, most do , I've rebuilt various engines over the years but when the time comes to rebuild mine I'm giving it to Trigger and paying for his expertise, the cost will be more than offset by me being able to spend my time out riding my other bikes and knowing the jobs been done perfectly (Trig you can knock a fiver off my bill for that 😄).



Cool I'll check that thread out, I'm also looking at a 4 into 1 so hopefully 135s will be in the right ballpark for me too.

Im expecting to have to get my hands dirty with the engine and could easily get someone else on the job for me but as I've never done this before I feel like if I don't do it now I'll never be able to. I'm off to the states for 11 weeks on the 25th with work so will have to put things on hold soon, and in not sure if I want the engine in bits for that long as when I come back ill probably never work out how it goes back together again ahah. On the flip side there's lots of cool bike shops where I'm going and my return luggage allowance is 50kg!
Title: Re: CB750 Barn find project - First Timer
Post by: MarkCR750 on August 05, 2016, 04:02:53 PM
Unfortunately the CB750 engines weighs 93kg otherwise you could have bought a replacement :) , lots of cheap spares out there though so make yourself a shopping list.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 05, 2016, 06:26:43 PM
Unfortunately the CB750 engines weighs 93kg otherwise you could have bought a replacement :) , lots of cheap spares out there though so make yourself a shopping list.

And not just spares, aftermarket parts are way cheaper too. Got a long list of stuff I'll be picking up from 4into1 as I'll be popping into San Fran for a day or 2. Basically I'm heading all around the south west so Vegas, San Fran, LA, San Diego and wherever else I feel like going to.. I think Carpy is somewhere around those parts but if anyone knows of any other decent supplies let me know and I'll check em out
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 05, 2016, 09:55:45 PM
I need some guidance on batteries,

The spare I had knocking around from an old CBR isn't holding a charge so I'll need to get something for this bike, I'm currently trying to quickly spend my wage on bike parts before my other half makes me be sensible.

I want something that's smallish and will have the juice for electric starts. I'm not going to run indicators and my headlight and tail light will probably be LED. Not sure whether it's best to go for AGM or Lithium and what amps/hour I'll need.

If anyone has any brand recommendations then please fire them over would be good to short list some likely contenders and see which gives the best bang for the buck  8)
Title: Re: CB750 Barn find project - First Timer
Post by: MarkCR750 on August 06, 2016, 08:15:44 AM
I use a motorbatt gel, tipped on its side under the tail fairing, sterling service for the last 18 months, can't remember the ID number but if you EBay "CB750 sohc battery" you'll find em, think it was about £50 from a seller called busters , lithium are ok but don't like shorts so don't fit one until your electrics are sorted, about £130.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 06, 2016, 09:41:50 AM
I use a motorbatt gel, tipped on its side under the tail fairing, sterling service for the last 18 months, can't remember the ID number but if you EBay "CB750 sohc battery" you'll find em, think it was about £50 from a seller called busters , lithium are ok but don't like shorts so don't fit one until your electrics are sorted, about £130.

Found them in eBay, MandP are selling them. Are physically smaller than the original battery or just lighter? Hasn't got any dimensions on there
Title: Re: CB750 Barn find project - First Timer
Post by: MarkCR750 on August 06, 2016, 08:17:38 PM
Not sure, about the same size and weight I think but the advantage is you can lie them on their side so they'll fit under race rep tail fairings, if you want light lithium is the way to go, so light they feel like an empty box.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 07, 2016, 04:00:36 PM
Not sure, about the same size and weight I think but the advantage is you can lie them on their side so they'll fit under race rep tail fairings, if you want light lithium is the way to go, so light they feel like an empty box.

Cool, after doing some more research I think if I went for a lithium is just be doing it for the sake of it and effectively wasting money so will go for an AGM.

In trying to source a 4 into 1 header, MAC performance do some full 4 into 1 exhaust systems but I don't like the silencers. In going to grab a stubby cone engineering reverse cone when I'm out in the states and it seems a waste to buy a full system to not use part of it. Any recommendations on where I can buy just the downpipes?
Title: Re: CB750 Barn find project - First Timer
Post by: yozzer74 on August 07, 2016, 06:43:50 PM
I think I've seen some on cycle x website.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 08, 2016, 07:33:54 PM
Managed to get a bit of time working on the bike today, fully stripped electrics, oil tank, and pretty much everything else bar the front end.

(https://s10.postimg.org/69sygif09/IMG_0279.jpg)

This bad boy was the biggest pain in the arse, fully seized and came pre-rounded by the previous owner

(https://s10.postimg.org/9uotzqjjt/IMG_0280.jpg)

Literally tried everything to get it off, cutting a slot and using an impact hammer, cutting new flats and trying to get a spanner on it, using this plumbers tool thing, heat, and finally going medieval and cutting it to bits and smashing it with a chisel.

(https://s10.postimg.org/hd7z8dawp/IMG_0282.jpg)

unfortunately I've damaged the filter housing, not too much but enough that i know its going to annoy me.

(https://s10.postimg.org/of5wukeih/IMG_0281.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 09, 2016, 07:25:41 PM
Dropped the lump out, was a bit of a wrestle even doing it the recommended lay-on-the-right-side-lift-off-the-frame method. Not looking forward to getting it back in when its all nicely painted..

(https://s9.postimg.org/nba9kxp6n/IMG_0285.jpg)
(https://s9.postimg.org/maa0vt873/IMG_0286.jpg)

Stripped the front end down, the fork stanchions were a right bastard to get out the lower triple tree, took a fair bit of brute force but they came out in the end. Currently mega struggling with getting the fork seals out the lowers, according to my haynes they should just lift out at this point but i can't get them to shift. Even tried cutting into them with a dremel but still couldn't get them to shift. I hope i haven't unwittingly destroyed something that isnt actually part of the oil seal  :o

(https://s9.postimg.org/86ir15qdb/IMG_0294.jpg)


Title: Re: CB750 Barn find project - First Timer
Post by: Chris400F on August 09, 2016, 09:36:34 PM
I had a problem removing my seals a while ago so I posed the question on here, and got the suggestion:
"Heating the fork legs in the area of the seals with a heat gun and gently prying the seals with a metal bicycle tyre lever has worked for me in the past".
So I tried it, and my seals then came out pretty easily.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 09, 2016, 09:58:35 PM
I had a problem removing my seals a while ago so I posed the question on here, and got the suggestion:
"Heating the fork legs in the area of the seals with a heat gun and gently prying the seals with a metal bicycle tyre lever has worked for me in the past".
So I tried it, and my seals then came out pretty easily.

I tried a hair dryer and then screwdrivers/pliers/all sorts to try and get them out but they didn't budge. Do the seals have a metal ring through them or have I literally been cutting into the fork leg?
Title: Re: CB750 Barn find project - First Timer
Post by: Chris400F on August 09, 2016, 10:23:28 PM
They do have a metal core. which from your picture it looks as if you have been cutting in to.
I don't know if a hairdryer puts out enough heat. You couldn't use one to strip paint, which you would do with a heat gun.
I think you may need to go hotter to get the metal of the fork leg to expand enough to loosen the seals. Maybe someone else will confirm this theory.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 09, 2016, 10:34:00 PM
They do have a metal core. which from your picture it looks as if you have been cutting in to.
I don't know if a hairdryer puts out enough heat. You couldn't use one to strip paint, which you would do with a heat gun.
I think you may need to go hotter to get the metal of the fork leg to expand enough to loosen the seals. Maybe someone else will confirm this theory.

I'll see if I can get my ancient blowtorch fired up then and just use it at a distance that doesn't melt everything
Title: Re: CB750 Barn find project - First Timer
Post by: Jontyp on August 10, 2016, 07:22:11 AM
I feel your pain on this one but the solution is more heat. There's nothing else to damage with heat except the seals and you're losing them anyway so have at it with a blow torch. I used a larger motorcycle tyre lever (has a perfectly designed hooked end just right for the job). Take your time, apply plenty of heat and they will come out (always assuming you've taken the wire retaining ring out first which it looks like you have).
Don't be afraid of using heat when stripping down old stuff (with the obvious proviso that you're not melting something important. It works great with steel parts stuck in aluminium (the seal inner ring will be steel) but even with the same materials it can be the best way to break a bond caused by years of corrosion.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 10, 2016, 12:23:43 PM
I feel you pain on this one but the solution is more heat. There's nothing else to damage with heat except the seals and you're losing them anyway so have at it with a blow torch. I used a larger motorcycle tyre lever (has a perfectly designed hooked end just right for the job). Take your time, apply plenty of heat and they will come out (always assuming you've taken the wire retaining ring out first which it looks like you have).
Don't be afraid of using heat when stripping down old stuff (with the obvious proviso that you're not melting something important. It works great with steel parts stuck in aluminium (the seal inner ring will be steel) but even with the same materials it can be the best way to break a bond caused by years of corrosion.

Cheers mate!

Just received a front brake caliper i bought yesterday from DK. Got it for £60 which is cheaper than they usually go for on the bay but its negative piston and pad seat.

The pad seat is number 17 here, just before i order one can someone confirm whether this would come with a new brake pad set or is it actually part of the caliper?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 10, 2016, 07:34:08 PM
Managed to get both fork seals out, went medieval with a dremel and then managed to hammer a flat head screwdriver behind it. As soon as they shifted slightly i could pull them out with pliers.

My fork tubes were rusty as hell so i ground off as much as i could. They're badly pitted but not on the actual part which slide in the lowers. Do you guys reckon i can get away with leaving them like this or should i at least paint them to stop them rusting again?

One done
(https://s9.postimg.org/clv8u3b27/IMG_0297.jpg)

two done
(https://s9.postimg.org/xy2qrrv0f/IMG_0301.jpg)
(https://s9.postimg.org/dcnyzvdfj/IMG_0300.jpg)

Could probably do with a bit of a sand as they're a bit rough, but currently all i can find is 240 grit wet and dry


Now the latest challenge is the DK special front brake caliper has a seized piston. Im not able to attach the front brake lever as the master cylinder is tits.. I have an air compressor but i can't screw it into the caliper as it just has a rounded nozzle. wrapped some insulation tape around some pliers and tried to pull it out but it doesn't budge. Any ideas? if i could fill it with something that wold dissolve the old crusty brake fluid that would be ideal!
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on August 10, 2016, 07:47:09 PM
They look normal for a early 750 fork. You will have to heat the caliper and you can use a grease gun to push the piston out.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 10, 2016, 08:44:02 PM
They look normal for a early 750 fork. You will have to heat the caliper and you can use a grease gun to push the piston out.

Ok cool so something like this yeah?

http://www.screwfix.com/p/hilka-pro-craft-manual-grease-gun-500cc/19235#product_additional_details_container

Might be a daft question but how do you actually attach a grease gun to the brake line hole?

secondly whats a good grease to get that I can use on the bearings and swing arm etc? Might as well get something i can use for other stuff
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on August 10, 2016, 08:54:21 PM
You need to find out if the fitting on the grease gun will fit the caliper at the pipe.
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on August 11, 2016, 06:59:36 AM
Multi purpose grease for everything and if you remove the end fitting from the grease gun pipe the thread will screw in about 1 1/2 turns into the pipe fitting hole as it is a different thread and that is enough  DO NOT FORCE IT or you wreck the caliper
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 11, 2016, 05:34:45 PM
You need to find out if the fitting on the grease gun will fit the caliper at the pipe.

Multi purpose grease for everything and if you remove the end fitting from the grease gun pipe the thread will screw in about 1 1/2 turns into the pipe fitting hole as it is a different thread and that is enough  DO NOT FORCE IT or you wreck the caliper

Got myself a grease gun earlier and it worked like a charm, thanks for the advice.

(https://s9.postimg.org/5watxnejz/IMG_0304.jpg)

Onwards to the next challenge, the front axle it stuck tight in the wheel, put a screwdriver through the end with a hole in and clamped it in a vice then heated the nut on the other side with a blow torch until it was so hot i was worried the aluminium bits would start to melt. got a spanner on it and hit it with a hammer for about 15 minutes and it didn't budge. I don't have a deep socket that size (17mm i think), looks like ill have to get one so i can get a breaker bar on it.

On another note I'm off rock climbing in switzerland! Peace out  8)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 17, 2016, 10:15:52 PM
Well I'm back and able to work on the bike for a few days before i head off again and the project gets put on ice until late october   ;D

Sprayed the upper  (previously rusty) parts of my fork stanchions today, look a lot better. Hammerite smooth rattle can stuff is actually pretty good.

Half on the lookout for a replacement right hand switch gear, some seem to have a headlight on/off switch below the kill switch and some don't, whats that all about? The listings were for the same year as well  :-\
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on August 18, 2016, 06:25:11 AM
UK has on/off US doesn't
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 18, 2016, 11:06:51 AM
UK has on/off US doesn't

Interesting, Is it/was it legislation in the US for bikes to always have lights on?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 18, 2016, 11:19:41 AM
Fork stanchions all painted. After grinding out all the rust i suppose i could have used some sort of filler to bring it all level but i don't think matters as it will all be hidden anyway in the clamps and under the gators.

(https://s3.postimg.org/orvjp2skj/IMG_0374.jpg)

Should hopefully stop them rusting again
Title: Re: Lights on or off........
Post by: MCTID on August 18, 2016, 09:20:04 PM
I lived in Canada from 1975 to 1977. I bought a new Suzuki GT 500 twin in 1976 and as soon as the ignition was switched on, the headlamp and taillight came on. That was the law in those days over there. Since then, I have always switched the lights on when I start the bike (or car).........what have you got to lose and imagine being in Court when some knob has knocked you off your bike and some clever Lawyer is trying to make out it was your fault...being able to say that you were showing your headlight, were wearing hi vis clothing, had a brightly coloured helmet and were obeying the speed limit, and driving sensibly.

As an old Boss of mine used to say 'It's all very well being in the right when you get knocked down and killed on a Pedestrian Crossing.........but your'e still dead' !
Title: Re: CB750 Barn find project - First Timer
Post by: mike the bike on August 18, 2016, 09:42:24 PM
Aye, there's not much comfort in saying from your hospital bed...."But it was my right of way"
Title: Re: Lights on or off........
Post by: Underdog1 on August 19, 2016, 09:15:41 AM
I lived in Canada from 1975 to 1977. I bought a new Suzuki GT 500 twin in 1976 and as soon as the ignition was switched on, the headlamp and taillight came on. That was the law in those days over there. Since then, I have always switched the lights on when I start the bike (or car).........what have you got to lose and imagine being in Court when some knob has knocked you off your bike and some clever Lawyer is trying to make out it was your fault...being able to say that you were showing your headlight, were wearing hi vis clothing, had a brightly coloured helmet and were obeying the speed limit, and driving sensibly.

As an old Boss of mine used to say 'It's all very well being in the right when you get knocked down and killed on a Pedestrian Crossing.........but your'e still dead' !

Valid point and I've always ridden in the day with dipped beam on too. However it's nice to have the choice to switch the headlight off with the engine reason should I ever wish to. As I'm going to replace the RH switch gear anyway I might as well get one which enables me to do this
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 24, 2016, 10:06:59 PM
Well I've got another 3 weeks or so until I'm back in the UK and continue this build. I went to 4-into-1 yesterday in San Francisco and ended up spending $400 on bits and pieces. Going to pick some headers up from MAC and a can from Cone engineering when I'm in LA shortly. It's such a shame there aren't any decent UK based suppliers for these kind of bits!
Title: Re: CB750 Barn find project - First Timer
Post by: Mace53 on September 26, 2016, 03:40:47 AM
Managed to get a bit of time working on the bike today, fully stripped electrics, oil tank, and pretty much everything else bar the front end.

(https://s10.postimg.org/69sygif09/IMG_0279.jpg)

This bad boy was the biggest pain in the arse, fully seized and came pre-rounded by the previous owner

(https://s10.postimg.org/9uotzqjjt/IMG_0280.jpg)

Literally tried everything to get it off, cutting a slot and using an impact hammer, cutting new flats and trying to get a spanner on it, using this plumbers tool thing, heat, and finally going medieval and cutting it to bits and smashing it with a chisel.

(https://s10.postimg.org/hd7z8dawp/IMG_0282.jpg)

unfortunately I've damaged the filter housing, not too much but enough that i know its going to annoy me.

(https://s10.postimg.org/of5wukeih/IMG_0281.jpg)
I've just been reading through this at work and it made me chuckle. I know your pain, I bet it was a huge relief getting it out!

Sent from my E2303 using Tapatalk

Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on October 27, 2016, 09:48:34 AM
I'm back baby!

It's been like 2 months but I'm now back in the UK ready to crack on with this heap.

Left the frame with a welder before I left, just gave him a call to see if I can pick it up and he still hasn't done it.. useless.

I've got a huge box of new parts from David Silvers and stuff I picked up stateside and all the parts that have come off the bike have been cleaned up. The main job left now is the engine and I literally don't know where to start! Is there any good guides out there on how to tear the 750 lump downs and what to look for?  I'm going to be out my depth but that's the only way I'll ever learn  ::)
Title: Re: CB750 Barn find project - First Timer
Post by: MarkCR750 on October 27, 2016, 09:41:36 PM
There are quite a few SOHC engine rebuild videos on youtube, no idea which one is best but I guess you can scan through a few of them and pick up some decent info.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on November 15, 2016, 11:54:45 AM
still not got stuck into the lump yet as I've moved house and now have no garage to hand :/

Going to have to do it bit by bit when I can return to where it's garages on weekends.

The frame has been at the welders since the beginning of time and he's still not done the rear hoop. Just got off the phone from him and he's having trouble getting the hoop itself fabricated as he can't do it in house. Apparently the bloke he's using to do it can only make it by welding 2 90 degree bends together giving it a squared off end.. something which I don't want.

Anyone know if anyone supplies pre made rear hoops?
Title: Re: CB750 Barn find project - First Timer
Post by: yozzer74 on November 15, 2016, 12:45:16 PM
One off welding and engineering do them
Title: Re: CB750 Barn find project - First Timer
Post by: Chris400F on November 15, 2016, 01:01:12 PM
Just search for 'frame hoop' on eBay and there are loads available.
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on November 15, 2016, 01:04:17 PM
I got mine off ebay, £25, with the slugs, ready to fit. Just cut the end tubes to your required length, insert and weld, simple. We have just fitted 2, 1 to a CB750 the other to my CB550
Title: Re: CB750 Barn find project - First Timer
Post by: onethumb on November 17, 2016, 04:41:11 PM
One off welding and engineering do them


+1
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on November 18, 2016, 07:57:11 PM
One off welding and engineering do them


+1

Ordered from these guys and it turned up today, looks like it's going to do the job perfectly.
Title: Re: CB750 Barn find project - First Timer
Post by: yozzer74 on November 19, 2016, 12:27:49 AM
Just been looking at your oil filter problem .I had a issue with mine .I bought a kit from voxonda in Holland .does away with old housing replace with modern filter .[attachimg=1][attachimg=2]
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on November 19, 2016, 09:55:41 AM
Just been looking at your oil filter problem .I had a issue with mine .I bought a kit from voxonda in Holland .does away with old housing replace with modern filter . (Attachment Link) (Attachment Link)

Was just a stuck bolt, got it off in the end my throwing the contents of my garage at it. Bought a pattern oil filter bolt from DS for like £8 so I'm all set
Title: Re: CB750 Barn find project - First Timer
Post by: Chris400F on November 19, 2016, 10:25:54 AM
What about the damaged housing? The face where the bolt seals doesn't look good in your pic.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on November 19, 2016, 02:51:22 PM
What about the damaged housing? The face where the bolt seals doesn't look good in your pic.

I think it's the o ring on the bolt that does the sealing rather than the bolt head itself?
Title: Re: CB750 Barn find project - First Timer
Post by: mike the bike on November 19, 2016, 03:01:07 PM
True
Title: Re: CB750 Barn find project - First Timer
Post by: Chris400F on November 19, 2016, 03:14:00 PM
Yes, you're probably right.
I was thinking the O ring was in the underside of the bolt like the tappet covers.
Title: Re: CB750 Barn find project - First Timer
Post by: mike the bike on November 19, 2016, 03:26:27 PM
The O ring sits in a groove in the bolt, a few mm from the head and seals against the side of the bolt hole in the filter housing.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on November 25, 2016, 05:11:53 PM
Had an afternoon to work on the bike today, decided I wanted to get the head and barrels off so I can take it to my new house a bit easier (going to have to work on it in the spare room!).

Took a little while as I'm having to learn as I go, also my Haynes manual is for both K and F models so can be misleading at times.

Got the rocker cover off fairly swiftly after having to carry the lump out the garage and giving it a quick clean off.

(https://s22.postimg.org/kwmcel03l/IMG_0165.jpg)

Didn't really understand how the manual wanted me to align the timing marks as it appeared to show the person turning the sprocket with their fingers..? I just took the stator cover off and cranked the engine around until I had access to both bolts that hold the camshaft sprocket onto the cam. Getting the cover back on was an absolute pain in the arse!

(https://s22.postimg.org/d5a7trlc1/IMG_0166.jpg)
(https://s22.postimg.org/z70i3t5tt/IMG_0167.jpg)

Some numbers I found on one of the cam shaft bases above cylinder 2, any ideas??

(https://s22.postimg.org/jzkijgdz5/IMG_0168.jpg)

After finding the correct pattern for tightening and loosening the cylinder head bolts I got the old boy off relatively pain free. I also dropped the chain down the tower for fun

(https://s22.postimg.org/5uephn4xt/IMG_0171.jpg)

Top of the pistons look very coked up.

(https://s17.postimg.org/52y4ztvmn/IMG_0172.jpg)

Underside of the head, not sure what I'm looking at here, will do some reading up.

(https://s17.postimg.org/ue2ugc47z/IMG_0173.jpg)

I bought a feeler guage for measuring piston gap, couldn't get the smaller feeler (.038mm) down the side of any of the pistons. Maybe I need to clean all the crud off first and check again. Anyone know what the max gap should be?

(https://s17.postimg.org/i0q09fejj/IMG_0174.jpg)

Eventually wrestled the barrels off and only damaged one cooling fin when I resorted to hammering wedges of wood. Not too fussed about this.

Wear on pistons, again I'm unsure what's acceptable so more research required.

(https://s17.postimg.org/lyd9yu1cv/IMG_0175.jpg)
(https://s17.postimg.org/3wyqerwpr/IMG_0176.jpg)

Barrels look smooth as glass, no obvious signs of wear to my untrained eyes.

(https://s17.postimg.org/h2e8kvqlb/IMG_0177.jpg)

Glad to be getting back into it, looking forward to getting the lump back to my new home so I can work on it home now so I can work on it in the evenings and spill dirty oil all over my beige carpets  8)
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on November 25, 2016, 06:12:28 PM
You don't measure the ring gap that way.
Title: Re: CB750 Barn find project - First Timer
Post by: MCTID on November 25, 2016, 10:48:14 PM
You most certainly don't measure Piston Ring gap that way. Check it out on Youtube. PMSL.
Title: Re: CB750 Barn find project - First Timer
Post by: mike the bike on November 25, 2016, 11:13:02 PM
The Haynes manual should explain how to measure the ring end gap.  If the bores are as smooth as glass, that's too smooth.  The bores need to be cross hatched,  I would suggest some tutorials on YouTube which will give you an understanding of the principles involved.  An engine rebuild is not something you want to fcuk up so keep asking questions.
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on November 26, 2016, 08:27:43 AM
I would be very concerned about all the pebbles in the bottom of the barrels  ;D ;D ;D
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on November 26, 2016, 08:46:45 AM
Thanks for the advice everyone, yeah I'm out my depth but if I don't do it now I'll never learn how.

Haven't actually looked into how you measure wear on the different bits, main effort was to just get the top end off to make it a little easier to transport (doesn't seem to make much difference though!).

How do the clymer manuals rate against the Haynes btw? Might get one of its a bit more descriptive
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on November 26, 2016, 08:51:56 AM
There are proper Honda manuals you can download from tinternet, maybe also in Ash's drop box but not sure. Also on SOHC.net
Title: Re: CB750 Barn find project - First Timer
Post by: Chris400F on November 26, 2016, 09:58:36 AM
....maybe also in Ash's drop box but not sure.
The CB750 Shop Manual is in the mega 750 download in Ash's Dropbox.
Fortunately for you (as the download has about 1,000,000 pages) it is right at the beginning so you won't have to hunt for it.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on November 27, 2016, 10:07:12 AM
....maybe also in Ash's drop box but not sure.
The CB750 Shop Manual is in the mega 750 download in Ash's Dropbox.
Fortunately for you (as the download has about 1,000,000 pages) it is right at the beginning so you won't have to hunt for it.

Cheers mate will check it out.

Went to Motorcycles Live at the NEC yesterday, was decent but didn't see any old Honda SOHCs. Had a look at some lifts and stands as it's a nightmare working on the engine on the floor. Didn't really have anything that looked useful to be honest.
For stripping and building a bike what are the best stands to use? Headstock stand and rear paddock stand? The scissor belly type lifts look good but I'd have to take the headers off to use one.

Also I've seen people adapt V8 engine stands rather than use bike specific ones, what's the advantage to this?

On another note I entered a competition to win some tyres and had to hold a tyre out in each hand for as long as I could. Came second to some unit, gutted! Could have done with some freebies!  ;D
Title: Re: CB750 Barn find project - First Timer
Post by: Spitfire on November 27, 2016, 10:29:35 AM
Here's my high tech stand that I used rebuilding mine worked great from bare frame to the finished article.
(http://i192.photobucket.com/albums/z244/DennisMcc/Progress%20shots/Rebuild-3.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on November 27, 2016, 11:58:06 AM
Here's my high tech stand that I used rebuilding mine worked great from bare frame to the finished article.
(http://i192.photobucket.com/albums/z244/DennisMcc/Progress%20shots/Rebuild-3.jpg)

Good effort! Might knock something similar up when the bike is ready to go back together circa Christmas 2027.

As far as engine stands go, there are a few work bench top cb750 specific ones on eBay for <£40, but also a lot of these:

http://www.mandp.co.uk/index.php/default/engine-stand-1500lbs.html

Would this support an SOHC engine without any sort of adapts plate being needed?
Title: Re: CB750 Barn find project - First Timer
Post by: SteveD CB500K0 on November 27, 2016, 04:18:48 PM
Quote from: Underdog1
On another note I entered a competition to win some tyres and had to hold a tyre out in each hand for as long as I could. Came second to some unit, gutted! Could have done with some freebies!  ;D

I went on Tuesday and must have sat on 50+ bikes, not many of which were <£20k

How long did you manage with the tyres?

2 mins was about the limit when I was watching.


Sent from my iPhone using Tapatalk
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on November 27, 2016, 08:42:37 PM
Quote from: Underdog1
On another note I entered a competition to win some tyres and had to hold a tyre out in each hand for as long as I could. Came second to some unit, gutted! Could have done with some freebies!  ;D

I went on Tuesday and must have sat on 50+ bikes, not many of which were <£20k

How long did you manage with the tyres?

2 mins was about the limit when I was watching.


Sent from my iPhone using Tapatalk

I got around the 2min30 mark with the winner beating me by 15seconds. If it had been another day maybe I could have one! I got a load of Dunlop branded crap though and met some really hot chicks back stage so wasn't all bad  :D
Title: Re: CB750 Barn find project - First Timer
Post by: Laverda Dave on November 28, 2016, 08:58:02 PM
You meet the nicest people on a Honda......
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 04, 2016, 07:57:51 PM
Been reading through the shop manual and it seems just to do the top end i need a myriad of tools including:

a micrometer, inside dial gauge, valve remover tool, valve guide remover, small dial gauge, valve guide driving tool, valve guide reamer, vernier caliper, cylinder gauge and probably a few more.

Obviously doing it this way is mega by the book, what i'd like to know is if there is some sort of list of the common things that need to be done or is it a case of absolutely everything needs to be put under the microscope? Im not one to cut corners but just thought I'd check before i shell out for a load of tools ill probably only use once.

I cleaned up the cylinder head cover and barrels today as they were still pretty filthy. Got the pistons out to measure the ring piston gap (which are all < 0.1mm on each) and cleaned up the pistons (one of the piston rings fell apart as i took it off  :-\).

The top of all the pistons look like this (the bits with carbon left on are low spots):

(https://s14.postimg.org/w4im2fe0x/IMG_0212.jpg)

Is this a red flag or typical wear?
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on December 05, 2016, 07:54:56 AM
Normal(ish)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 07, 2016, 07:39:22 PM
Normal(ish)

just waiting on some micrometers to arrive in the post so I can measure a few things up, apart from the piston diameter at the skirt end 90 degrees to the hole being less that 60.85mm and the piston ring grooves being excessively worn is there anything else I should look out for?

Also I need to get a valve spring compressor, is there a need to spend much money on this or will a cheap flea bay one do the job just as well?

http://www.ebay.co.uk/itm/262711661056?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

This project is going along painfully slow at the moment as I've been really busy at work and will be off out the country for another 5 weeks in Jan. Need to try and get as much as I can done over xmas!

On a positive note I bought a cheap engine stand and adapted it to hold a motorbike engine, probably £50 all in which I was happy with! Will get some pics up when my phone stops being so tempermental.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 11, 2016, 08:33:15 PM
Here she is, living room engineering at its finest!

(https://s23.postimg.org/sb1z2a9cr/IMG_0234.jpg)
(https://s23.postimg.org/xazfa8ezf/IMG_0235.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: MarkCR750 on December 11, 2016, 10:30:19 PM
Nice work!
Title: Re: CB750 Barn find project - First Timer
Post by: yozzer74 on December 12, 2016, 06:34:16 AM
I take it your not married then
Title: Re: CB750 Barn find project - First Timer
Post by: Rozabikes Tim on December 12, 2016, 07:36:19 AM
Wow thats a big decoration on your tree. Ho ho ho....
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 12, 2016, 10:07:03 AM
Wow thats a big decoration on your tree. Ho ho ho....

I've worked hard getting my girlfriend into motorbikes, bought her a jacket and booked her CBT for xmas so she's actually cool with it  8)

I'm taking my cylinders to a machine shop today to get measured. If I do have to get them rebored is there any reason not to go straight to the 1mm max rather than doing the minimum necessary?

Hopefully it will be within specs and I won't have to bother but just thinking if I'm going down that route I might as well get the most out of it right? The workshop doesn't state what diameter the cylinders need to be rebored to for the different size overbite pistons which is a bit confusing  :-\

Title: Re: CB750 Barn find project - First Timer
Post by: Spitfire on December 12, 2016, 11:33:11 AM
That's a a great stand, likes it

Cheers

Dennis
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 12, 2016, 04:49:18 PM
Cancel my last i had the barrels measured up and they are all good, just getting a hone.

Also took my head in and they checked all the valves sealed correctly but they didn't check any clearances as i still had the valve springs all attached (my spring compressor actually arrived today and i went straight from work to the machine shop) but they were confident they were all good (they were both also motorbike enthusiasts), should i be alright to take their word on it or should i still take the valves to bits? They did however find the head was ever so slightly warped so is getting a light skim.

Guess thats me about ready to split the cases then  :D

Jut thinking ahead slightly for once, what gasket/seal sets do you guys recommend? I see the cycle x set gets good reviews but seems difficult to get in the UK..

Theres cheap 'NE brand' ones on eBay and some even cheaper seemingly unbranded ones but I'm wary of either so suggestions appreciated!



That's a a great stand, likes it

Cheers

Dennis

Thanks mate, made more sense to me to buy a cheap engine stand and just adapt it for a bike engine rather than buying a dedicated bench top engine stand for almost the same price.
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on December 12, 2016, 05:39:13 PM
Worth changing valve stem seals
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 12, 2016, 05:50:20 PM
Worth changing valve stem seals

Ill look into it  :)

Just doing another bulk order on DS, do my cam chain tensioner bits look like they are kaput?

(https://s27.postimg.org/sy1wi41z7/IMG_0243.jpg)
(https://s27.postimg.org/g7xo50u0z/IMG_0244.jpg)
(https://s27.postimg.org/t0ls4y5mr/IMG_0245.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 13, 2016, 03:16:28 PM
Got my barrels and head back from the shop


(https://s28.postimg.org/5i0b6h83h/IMG_0248.jpg)
(https://s28.postimg.org/5ja8zw9x9/IMG_0249.jpg)

They are just measuring my pistons up for me now as I don't really trust my £5 eBay micrometer.

Still haven't quite wrapped my head around the valves, if they've been vacuum tested and seal well does that mean they don't need lapping at all?
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on December 13, 2016, 03:59:06 PM
Valves probably not but definitely change the seals, tensioner is expensive but worth changing as old rubber goes hard and can break causing disassters
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 13, 2016, 06:20:10 PM
Valves probably not but definitely change the seals, tensioner is expensive but worth changing as old rubber goes hard and can break causing disassters

Yeah I thought that might be the case, piston rings seem fine but is this one of the 'might as wells' when it's in bits?

Just spent the last 90 minutes getting these boys clean

(https://s23.postimg.org/3pm6318vv/IMG_0254.jpg)

They were really coked up bad
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 13, 2016, 09:44:50 PM
Just spent another £180 at DS  :-X

Pretty much just cam chain tensioner bits and throttle cables.. didn't even include a camchain either.

Still on the hunt for some decent gasket sets of anyone has any ideas!
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 17, 2016, 01:12:31 PM
Probably going to go with a vesrah gasket set as they seem the most complete, may need to still buy the odd bit though.

Just looking at piston ring part numbers on CMSNL and it's confusing what the actual part number is..

http://www.cmsnl.com/honda-cb750k6-four-england_model14383/partslist/E15.html#results

Seen some NOS on eBay part number 13011-300-024, would these fit?
Title: Re: CB750 Barn find project - First Timer
Post by: UK Pete on December 17, 2016, 04:46:46 PM
loving your enthusiasm underdog, the engine stand looks great and fair play to you for getting the all clear from missis to work in the front room, its so easy to spend a small fortune at ds, its amazing how much a engine build can swallow money, keep up the good work fella
pete
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on December 17, 2016, 06:03:33 PM
Probably going to go with a vesrah gasket set as they seem the most complete, may need to still buy the odd bit though.

Just looking at piston ring part numbers on CMSNL and it's confusing what the actual part number is..

http://www.cmsnl.com/honda-cb750k6-four-england_model14383/partslist/E15.html#results

Seen some NOS on eBay part number 13011-300-024, would these fit?

What size do you require, I have a large stock of Honda piston rings.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 17, 2016, 07:32:41 PM
Probably going to go with a vesrah gasket set as they seem the most complete, may need to still buy the odd bit though.

Just looking at piston ring part numbers on CMSNL and it's confusing what the actual part number is..

http://www.cmsnl.com/honda-cb750k6-four-england_model14383/partslist/E15.html#results

Seen some NOS on eBay part number 13011-300-024, would these fit?

What size do you require, I have a large stock of Honda piston rings.

Standard size for the 750 mate, PM sent  :)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 18, 2016, 04:56:25 PM
As I'm now home for a couple of weeks for xmas I stuffed the anchor in the boot of my car and took it into my family home where I can utilise the garage rather than ruining the carpet in my house  ;D

Took everything off in preparation to split the cases, had to leave the clutch and rotor on as i don't currently have the correct tools.

(https://s29.postimg.org/kkplbvmev/IMG_0284.jpg)

I had to take the engine off the stand after removing all the upper case fixings to split the cases so just chucked onto a workmate type bench, was a little worried about how precarious it was going to be but its weighted enough at the rear to balance nicely.

(https://s29.postimg.org/bqyourzg7/IMG_0285.jpg)

Removed all the lower case fixings and tapped around the edges with a block of wood and hammer and without too much trouble cracked the old girl open.

(https://s27.postimg.org/rnme16ddv/IMG_0286.jpg)

Happy that this was relatively pain free and will have time to dive into it deeper tomorrow.

A few quick questions though -

I need the engine fully stripped down for cleaning and painting, will the rotor now come out with the crankshaft in one piece and will the clutch come out with the transmission main shaft? or do i still need the special tools to get them out?

For the gear shift mechanism i only removed the shift arm and counter shaft bearing holder, couldn't get the other bits off as i think the screw holding the gear shift side plate is staked in place?

(https://s27.postimg.org/xsdwei5hf/IMG_0289.jpg)



Title: Re: CB750 Barn find project - First Timer
Post by: hairygit on December 18, 2016, 05:01:48 PM
The crank will lift out with the rotor attached, as will the clutch and gearshaft. There is no need to dismantle the pins and endplate on the selector drum at any point unless there was a gear selection problem before you stripped it.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 18, 2016, 06:23:22 PM
The crank will lift out with the rotor attached, as will the clutch and gearshaft. There is no need to dismantle the pins and endplate on the selector drum at any point unless there was a gear selection problem before you stripped it.

That's good news then, will take it to bits tomorrow then. I never actually rode it before I stripped it as it was sold as a non runner, carbs were all gunked up so I cleaned those up and got her running before tearing her apart but the drive chain was rusted so didn't want to actually try riding it first! I'm hoping the reason it was layed up was just the carbs and so far it doesn't look like it's had much of a hard life at all.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 18, 2016, 07:43:09 PM
Final question of the day guys..

Would putting the engine casings/head/barrels etc through a dish washer with regular dish washer tablets damage either the parts or the dish washer itself? Considering doing it tomorrow secretly  ;D
Title: Re: CB750 Barn find project - First Timer
Post by: hairygit on December 18, 2016, 08:05:41 PM
Really can't answer that one, my dishwasher would notice and complain bitterly! ;D Although Ashimoto may know, he will try almost anything once!
Title: Re: CB750 Barn find project - First Timer
Post by: totty on December 18, 2016, 08:11:21 PM
Should be fine, I had a mate that did it all the time, he did a cylinder head for me once.
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on December 18, 2016, 08:44:55 PM
Don't put a dishwasher tablet in unless it's a non corrosive type, otherwise it may send all the alloy black. It will also make any steel parts, like the liners go rusty immediately. Maybe consider an acid dip clean (needs to be done professionally) to get all old paint/oil/sh*t off, achieves a far better result.

Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 18, 2016, 08:56:58 PM
Don't put a dishwasher tablet in unless it's a non corrosive type, otherwise it may send all the alloy black. It will also make any steel parts, like the liners go rusty immediately. Maybe consider an acid dip clean (needs to be done professionally) to get all old paint/oil/sh*t off, achieves a far better result.

Surely the parts washers at machine shops are pretty much an industrial dish washer? Guess I'll try with just hot water after scrubbing the worst of the grime off.

I'll dry them off with an air compressor and any steel bits can get a wipe of WD40 when will report back tomorrow!
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on December 18, 2016, 08:59:59 PM
Industrial parts washers use chemicals but, non corrosive and also an inhibitor to stop them rusting.
Title: Re: CB750 Barn find project - First Timer
Post by: Green1 on December 18, 2016, 09:07:34 PM
I have put a complete cg engine in the dishwasher that came out spotless.A few rocker covers,Cylinder head,carbs and now a wiring loom all with a dishwasher tab and all were fine.  ;)
WD40 on the liners is a good idea I did the same to prevent rust
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 18, 2016, 10:27:30 PM

Industrial parts washers use chemicals but, non corrosive and also an inhibitor to stop them rusting.

That's a fair one, will look up what's actually in the dishwasher tabs and how alkaline it is.

I have put a complete cg engine in the dishwasher that came out spotless.A few rocker covers,Cylinder head,carbs and now a wiring loom all with a dishwasher tab and all were fine.  ;)
WD40 on the liners is a good idea I did the same to prevent rust

Was that with just regular dishwasher tabs?
Title: Re: CB750 Barn find project - First Timer
Post by: Green1 on December 18, 2016, 10:34:31 PM
I used Finish dishwasher tabs
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 19, 2016, 04:43:32 PM
So i put a few bits through the dishwasher on the hottest wash without any dish wash tablets.

(https://s27.postimg.org/3ujhne103/IMG_0292.jpg)

Prize to anyone who said steel parts will rust immediately!

(https://s27.postimg.org/dt4g9vafn/IMG_0298.jpg)

Wasn't so bad though as a bit of oil on a cloth cleaned it right off..

(https://s27.postimg.org/ou46sms2b/IMG_0299.jpg)

Apart from the didn't get much else done today to be honest, Im trying to get the kick starter shaft out of the lower case but i can't get the little stopper pin out. As per the picture in the workshop manual I've tried a pair of side cut pliars but it wont budge at all, any suggestions?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 19, 2016, 06:16:08 PM
Even though the crankshaft and final drive sprocket  were seemingly loose I was unable to actually remove them from the upper case. Just nipped back out to the garage and prised the thick rubber seal off on the end of both and they lifted right out so the upper case is now empty  :)

(https://s27.postimg.org/xr5iss3zn/IMG_0303.jpg/img]

Now the mainshaft is out am i able to remove the clutch without a clutch tool? Thought id ask before i go in with any brute force.

Also I've got these Q1 markings on both cases, any idea what thet could mean?

[img]https://s27.postimg.org/vy2m4gisz/IMG_0302.jpg)

(https://s27.postimg.org/wmbgnehir/IMG_0301.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 20, 2016, 07:05:24 PM
Had a netflix and chill day today so didn't spend much time in the garage. I managed to get that pesky kick starter stopper pin thing out with the help of a blowtorch and mole grips, took one hell of an effort though!

All thats left in the cases now is the transmission countershaft. Ive got shift fork ears and shaft off, top gear, bottom gear and primary drive gear out but the rest of the countershaft (with remaining 3 gears) wont lift out as pictures in my haynes manual as the gearshift drum is in the way by like 1mm. Is it possible to get them out without removing the gear shift drum (i wanted to avoid having to remove that staked screw on the gear shift side plate...

(https://s30.postimg.org/5yobufo9d/IMG_0306.jpg)

Also if I'm going to paint the whole engine is it better to do it fully stripped down or when its fully assembled (the later seems a lot less admin taping things off!)?

Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on December 20, 2016, 07:54:23 PM
Hope you numbered the crank case shells and they have to go back in the same place.
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on December 21, 2016, 07:39:22 AM
Take the gear selector drum out and you will have room to remove the cogs ;)
You don't have to take the drum apart. If you remove the natural switch (that is under the engine) the whole drum will pull out.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 21, 2016, 06:52:29 PM
Take the gear selector drum out and you will have room to remove the cogs ;)
You don't have to take the drum apart. If you remove the natural switch (that is under the engine) the whole drum will pull out.

Yep that was the badger! Started the cleaning process today.. well tried too. Went out looking for degreaser and ended up buying 5L of holts brake cleaner for £11 thinking it would do the trick.

Sprayed the crank cases liberally, left a few minutes and then blasted with a pressure washer annnnnd nothing happened. Despite the stuff cutting through the crap like theres no tomorrow its so volatile it just evaporates which solidifies all the grease again before you can even wash it off. Tried in the sink with some hot soapy water which again didn't really do the job, the only thing which did work was spraying small areas at a time with the brake cleaner and wiping it down with a paper towel. Took ages to do the bottom case but eventually i got to this:

(https://s28.postimg.org/q04gyl171/IMG_0308.jpg)
(https://s28.postimg.org/yjnuwc9jh/IMG_0309.jpg)

Still needs a bit more work but got the worst of the grime off. My local motor factors also stocks Gunk and Jizer, would either of these fit the bill better (i.e. apply, agitate with brush, leave, power wash off)?

Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on December 21, 2016, 07:14:00 PM
Follow this link Phil, it may be of use to you.
http://www.sohc.co.uk/index.php/topic,10783.msg78781.html#msg78781
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 22, 2016, 10:51:37 AM
Follow this link Phil, it may be of use to you.
http://www.sohc.co.uk/index.php/topic,10783.msg78781.html#msg78781

I've read through this previously and I don't think I can afford £2k of acid right now. Good to see how it's done on a commercial level though. Been thinking I may even not paint the engine at all depending how well it cleans up, I quite like the patina in the aluminium parts..

I've bought an m20x80 bolt which I'm going to grind the end down slightly and use as a rotor tool, are there any decent life hacks out there for the clutch tool? Pretty expensive to buy!
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on December 22, 2016, 11:04:33 AM
Hahaha, no, you don't have to pay 2K, that's how much it costs to fill an industrial size tank !!!. It only costs somewhere around £65 to have all the cases stripped this way. Also, I know Trig would say the same but, if you leave your engine 'naked' as it were, ie, not painted, it would end up as a fir ball of corrosion in no time at all.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 22, 2016, 01:45:00 PM
if you leave your engine 'naked' as it were, ie, not painted, it would end up as a fir ball of corrosion in no time at all.

Do you reckon? my cases still have the original paint on them and all in all its mostly still there, the barrels, head, valve cover, side covers all came as bare aluminium from the factory no?
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on December 22, 2016, 01:51:14 PM
The engines are painted and lacquered from the factory and the casings were satin polished and lacquered to protect them from corrosion.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 22, 2016, 03:33:19 PM
The engines are painted and lacquered from the factory and the casings were satin polished and lacquered to protect them from corrosion.

Ok cool well every days a school day  :)

However if the bike ha gone 4 years without rusting I'm sure it can handle a few more without falling to bits, the more i see bikes like this:

(http://thebikeshed.cc/wp-content/uploads/2014/08/86MC-CB750-5.jpg)

The more i think i like the worn in 'patina' look. Anyway I'm not going to rush into spraying my engine bits now ill see how i feel in a week or so.

I bought some Hondabond HT gasket sealer on the bay a few days ago after mistaking it for Hondabond 4 (damn you port!). Doesn't seem the Hondabond 4 is easily available in the UK and threebond seems a good alternative. However my research shows that Threebond have changed their formula a few times as they have been forced to remove various chemicals.. Does anyone know if 1184 is the right one to go for?

http://www.ebay.co.uk/itm/111631190580?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on December 22, 2016, 03:43:11 PM
I am far from an expert but the paint on your engine, by what I can see in your piccies, looks in quite good order. If you were to strip the varnish / paint off and then leave it bare that is when the alloy oxidises and goes furry. Also, an Engineer will tell you it's not important what the outside of the engine looks like, it's how it's built and how it performs on the inside that is important  ;D ;D ;D
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 22, 2016, 04:32:02 PM
I am far from an expert but the paint on your engine, by what I can see in your piccies, looks in quite good order. If you were to strip the varnish / paint off and then leave it bare that is when the alloy oxidises and goes furry. Also, an Engineer will tell you it's not important what the outside of the engine looks like, it's how it's built and how it performs on the inside that is important  ;D ;D ;D

I think we've got our lines crossed a little here, when i said i may not even paint the engine at all i meant clean up and leave as is with the factory paint on  :)
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on December 22, 2016, 04:34:44 PM
No crossed wires, I'm agreeing with you Phil  ;D ;D. If it's got good paint on it why bother taking it off. Personally, it's all about bling with me, an engine has got to look blingy (must be a girl thing!!!!)
Title: Re: CB750 Barn find project - First Timer
Post by: Chris400F on December 22, 2016, 05:24:38 PM
.... an engine has got to look blingy (must be a girl thing!!!!)
.... and the paintwork has to match your nail varnish (another girl thing!!)
Title: Re: CB750 Barn find project - First Timer
Post by: mike the bike on December 22, 2016, 06:13:54 PM
There's a clutch tool on fleabay for under £13.  I've used mine loads of times on mine and various mates with 400s

http://www.ebay.co.uk/itm/Honda-CB400-FOUR-FOUR-400-4-CLUTCH-TOOL-SOCKET-SERVICE-GEARBOX-SPECIAL-hj-/262755821419?hash=item3d2d77a76b:m:meuG-nUEmAj41YB5aW1ntig
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 22, 2016, 07:07:46 PM
There's a clutch tool on fleabay for under £13.  I've used mine loads of times on mine and various mates with 400s

http://www.ebay.co.uk/itm/Honda-CB400-FOUR-FOUR-400-4-CLUTCH-TOOL-SOCKET-SERVICE-GEARBOX-SPECIAL-hj-/262755821419?hash=item3d2d77a76b:m:meuG-nUEmAj41YB5aW1ntig

Good find, ordered one  :)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 22, 2016, 07:15:01 PM
in another train of thought I have some Renthal Ultralows which i was hoping to be able to internally wire.

http://www.demon-tweeks.co.uk/motorcycle/handlebars/renthal-superbike-ultra-low-bars?gclid=CIGBx_fAiNECFRa3GwodfdAMFA

Ive had them sitting around for a while but picked them up today and realised they arent completely hollow, they are blocked off about 4 inches into either side.

Can i still internally wire them or should i avoid chopping up these aluminium bars and find some steel ones instead?
Title: Re: CB750 Barn find project - First Timer
Post by: mike the bike on December 22, 2016, 07:25:35 PM
When you use the clutch tool, make sure it's seated properly by tapping it all the way in, otherwise something will get chewed up.
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on December 23, 2016, 07:33:59 AM
DO NOT under any circumstances cut holes for wires in ally bars, if you look at Honda steel bars they are strengthened where the wires exit at the centre. Way back when saw many "broken" bars where holes had been cut cos the owner didn't want to pay Honda's replacement prices
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 23, 2016, 09:10:21 AM
DO NOT under any circumstances cut holes for wires in ally bars, if you look at Honda steel bars they are strengthened where the wires exit at the centre. Way back when saw many "broken" bars where holes had been cut cos the owner didn't want to pay Honda's replacement prices

Hmm that's a shame then, how do people tend to run these then? Externally wire them?
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on December 24, 2016, 08:31:13 AM
Yup
Title: Re: CB750 Barn find project - First Timer
Post by: Darkness on December 24, 2016, 09:24:57 AM
You can buy second hand dishwashers on Gumtree or eBay for £10, so why take a chance on the one in the house?  At that price, use it on a few small items first, then give everything a wash once you know what effect it has on parts.
We expect feedback though, with recommendations on which tablets give best results.  :D
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 24, 2016, 10:14:03 AM
I definitely want to internally wire my bars so been looking at steel bars today, probably going to get some EMGO super bike bars although I'll have to get the from US eBay, its crazy how hard it is to get a decent set of steel low rise bars in the UK. Should be no problem drilling them though. Yes I'm getting ahead of myself as my bike is still in 8 gazillion pieces  ;D

Continued cleaning up a load of parts last night (wild), still have a small amount of sealant left on the cases (well it's more like residue now) I started using a razor blade to scrape it off but this marks the aluminium.. would a fine sand paper be ok to get this off? I don't really fancy paying £10 for a can of gasket remover I'm barely going to use. If not is there anything else that can be used?

Merry Christmas Eve everyone!
Title: Re: CB750 Barn find project - First Timer
Post by: mike the bike on December 24, 2016, 10:35:37 AM
Use a blunt scraper or Stanley blade, one that doesn't dig into the aluminium
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 24, 2016, 10:36:30 AM
Use a blunt scraper or Stanley blade, one that doesn't dig into the aluminium

Stanley blade sounds a good shout
Title: Re: CB750 Barn find project - First Timer
Post by: hairygit on December 24, 2016, 11:47:20 AM
I definitely want to internally wire my bars so been looking at steel bars today, probably going to get some EMGO super bike bars although I'll have to get the from US eBay, its crazy how hard it is to get a decent set of steel low rise bars in the UK. Should be no problem drilling them though. Yes I'm getting ahead of myself as my bike is still in 8 gazillion pieces  ;D

Continued cleaning up a load of parts last night (wild), still have a small amount of sealant left on the cases (well it's more like residue now) I started using a razor blade to scrape it off but this marks the aluminium.. would a fine sand paper be ok to get this off? I don't really fancy paying £10 for a can of gasket remover I'm barely going to use. If not is there anything else that can be used?

Merry Christmas Eve everyone!   You will still need bars that are strengthened where the cables exit the bars between the yoke clamps, as the slot needed to exit the cables is quite large, and Honda strengthened them for a good reason!
Title: Re: CB750 Barn find project - First Timer
Post by: Chris400F on December 24, 2016, 02:38:27 PM
What about bars off a different model, say a 400? These are pretty low rise and the standard wiring is internal so the holes are already in place.
Title: Re: CB750 Barn find project - First Timer
Post by: Seabeowner on December 24, 2016, 03:13:48 PM
If I use a Stanley blade I use it mounted in one of those handles they make for removing paint from window panes. But go gently.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 24, 2016, 03:56:58 PM
What about bars off a different model, say a 400? These are pretty low rise and the standard wiring is internal so the holes are already in place.

I thought about that to be fair but after a little research some people say they find them too narrow for the bigger bike. Would be ideal though do get some ready drilled for the wiring!
Title: Re: CB750 Barn find project - First Timer
Post by: Chris400F on December 24, 2016, 05:13:51 PM
What about bars off a different model, say a 400? These are pretty low rise and the standard wiring is internal so the holes are already in place.

I thought about that to be fair but after a little research some people say they find them too narrow for the bigger bike. Would be ideal though do get some ready drilled for the wiring!
They are quite narrow, not sure of the exact width without measuring.
Maybe the bars from a larger UK spec bike, say a 750 F1, would do. Pretty sure they would be flatter than the ones shown in the photo of your bike at the start of this thread.
DS sell replica ones, you could have a look there.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 24, 2016, 05:41:51 PM
Yeah the euro spec 750k bars are much lower than the US mini ape hangers! Still a little higher than I'd like though.

I'd like to end up with a front end that looks similar to this:

(http://thebikeshed.cc/wp-content/uploads/2016/05/cb750-2.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 26, 2016, 08:47:08 PM
Just chilled out the last 2 days and been too full of booze and cheese to even think about going in the garage.

I have however purchased a transistor ignition from Hondaman and sort of solved the handlebar problem.. my mrs is travelling to the states in Jan and I've found a local bikeshop that sells cool bars and also Mac 4 into 1 exhausts. Probably going to get a few more bits too as it'll save me a load on shipping and VAT.

Been thinking about my wiring loom today. I've got the crusty old original one which I want to replace, and I'm doing away with indicators, got a solid state reg rec and will have an electronic ignition.. am I better to buy a new loom from somewhere like DSS or put my own together? Basicwlly I know how to solder but have never tried something this big so skills may be a little lacking
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on December 27, 2016, 06:02:01 AM
Just chilled out the last 2 days and been too full of booze and cheese to even think about going in the garage.

I have however purchased a transistor ignition from Hondaman and sort of solved the handlebar problem.. my mrs is travelling to the states in Jan and I've found a local bikeshop that sells cool bars and also Mac 4 into 1 exhausts. Probably going to get a few more bits too as it'll save me a load on shipping and VAT.

Been thinking about my wiring loom today. I've got the crusty old original one which I want to replace, and I'm doing away with indicators, got a solid state reg rec and will have an electronic ignition.. am I better to buy a new loom from somewhere like DSS or put my own together? Basicwlly I know how to solder but have never tried something this big so skills may be a little lacking

If you contact a member RGP750, I think he still has a new 750 loom that he bought by mistake  ;)
Those bars look like UK 750 STD, which have been powder coated.
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on December 27, 2016, 05:37:41 PM
Hondamans system still uses the original points and coils and for what you want the easiest solution is a standard loom and switchgear just not connecting the bits you don't use
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 28, 2016, 06:16:46 PM
Few things happened today as the Mrs is back at work  ;D

Firstly the welder rocked up with my frame in the back of his van, its only taken him since august to weld the rear hoop on!  :o Looks like he's done a good job though just don't think ill be using him ever again.

(https://s27.postimg.org/cdusuuzsj/IMG_0331.jpg)

Now all my engine internals are nice and clean I can check things for wear properly, the bikes only got 18.5k on the clock and everything so far has been good. I haven't taken the con rods off the crank shaft as I've heard told the con rod bolts can't be reused so was only going to look at the rod bearings if i had reason to look deeper (i.e. if i found significant wear elsewhere).

I got some plastiguage from eBay which I'm a bit dubious about, it came in a pack like this:

(https://s27.postimg.org/r643zxv3n/IMG_0342.jpg)

And even though its the right size for doing the crankshaft bearings (according to the pack) whenever I've seen pics/vids of people plastiguaging their crank bearings they seem to be using the green one.

Anyway i applied the stuff like so:

(https://s27.postimg.org/exv12pcqb/IMG_0337.jpg)

And torqued down the 10x 8mm lower crank case bolts to 17.5 lbs.ft in the correct pattern being careful not to turn the crankshaft then took the lower crank case back off giving me this:

(https://s27.postimg.org/ytr0i8trn/IMG_0338.jpg)
(https://s27.postimg.org/wdp74eboz/IMG_0339.jpg)
(https://s27.postimg.org/3pc9169ir/IMG_0340.jpg)
(https://s27.postimg.org/tm5xdsd6b/IMG_0341.jpg)

Now i thought the plastiguage was supposed to stay in one piece and not stick so much to both surfaces? According to the measurements I've got from it they are all ok (max 0.08mm) but it just doesn't seem to have worked right. Maybe i bought some fake stuff I'm not sure but it was definitely a pain to clean off afterwards!

Apart from this i cleaned up some AC generator parts and seem to have lost one of the washers for one of the 3 bolts that hold the field coil to the cover. I didn't realise there even was washers here until they started flying off when i used the pressure washer on the cover  ;D Hopefully ill find something the right size knocking about so i don't have to part with six billion pound for one with Mr Silvers.

I also found this thin metal tab although I'm not sure its part of anything could just be something that was already sitting on my workbench. Anyone recognise this?

(https://s27.postimg.org/q8xor2jlf/IMG_0336.jpg)

So just waiting on a few bottom end seals to come and then i can start putting the old girl together again. For assembly of the engine I understand that a lot of the internals require submerging in oil as it can take a full minute of run time for oil to reach things like the main shaft.. is there a specific oil recommended for this? Ive got GTX Semi synthetic 10w40 and Triple QX semi synthetic 10w40 for diesel engines to hand, was thinking about using the GTX for assembly and first couple of hundred miles before switching the the Triple QX which has the turbo additive which I've seen recommended for these old bikes.

Finally when using the haynes manual and workshop manual for disassembly at no point was it mentioned to keep track of which primary chain went where and which direction it went in so i didn't. Hondamans book emphasises how important it is to do this as the chains wear unevenly. With 18.5k on my bike what sort of issues could arise from putting the primary chains back differently?

So in summary, todays questions are:

1. Do you think i have dodgy plastiguage  ;D
2. Does anyone recognise that little metal tab as part of the AC generator?
3. What oil should i use to soak my internals in before assembly?
4. Will the universe explode if i put my primary chains on backwards?
5. Is father christmas real?
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on December 28, 2016, 06:49:25 PM
1) Nothing wrong with that plasigauge. That is down to the operator  ;D
2) Never seen that tab before.
3) No need to soak parts in oil. Use a assembly compound on the shells and cam. A little oil on the bores.
4) No direction for chains, just staggered.
5) I will send you some more sealing washers for the alternator with the other parts.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 28, 2016, 06:57:14 PM
1) Nothing wrong with that plasigauge. That is down to the operator  ;D
2) Never seen that tab before.
3) No need to soak parts in oil. Use a assembly compound on the shells and cam. A little oil on the bores.
4) No direction for chains, just staggered.
5) I will send you some more sealing washers for the alternator with the other parts.

Cheers Trigger you're the man! Would you recommend a semi synth oil for initial wear in after a rebuild? I'm sure I've read somewhere about mineral oil being good to use first off as it helps make the seals and gaskets more oil tight.. Cant seem to find where i got this from though!
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on December 28, 2016, 07:06:01 PM
mineral is good for running in.

This is how I do my hoops, a plate for the seat to bolt to and indicator mounts. [attachimg=1]
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 28, 2016, 07:11:50 PM
mineral is good for running in.

This is how I do my hoops, a plate for the seat to bolt to and indicator mounts. (Attachment Link)

yeah I'm not done with the frame yet, i wanted to hold off having any plates welded on until I'd made the seat pan and figures out how I'm going to mount the rear mud guard like this:

(http://thebikeshed.cc/wp-content/uploads/2014/08/86MC-CB750-3.jpg)
(http://thebikeshed.cc/wp-content/uploads/2016/05/cb750-2.jpg)

Im also not going to be running indicators. Do you fab your rear hoops up yourself? Looks decent.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 28, 2016, 07:25:33 PM
mineral is good for running in.

Is all mineral oil the same sort of stuff? I mean i could buy a cheap motorbike specific running in oil like this:

http://www.ebay.co.uk/itm/Motorbike-Running-In-Oil-Breaking-In-Oil-Mineral-5L-5-Litres-/111859859019?hash=item1a0b5dfe4b:g:Q4IAAOSw1S9Wf~xH

or I could go to home bargains and get something really nasty  ;D
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on December 28, 2016, 07:42:27 PM
Found this even cheaper >> http://www.ebay.co.uk/itm/Shell-Advance-SX-4-15w-40-4-Stroke-Mineral-Motorcycle-Engine-Oil-4-Litre-/370240162761?hash=item5634088bc9:m:mYkJhPLyxmonhvkSWF-7lOQ
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 29, 2016, 04:57:07 PM
Bit bored of looking at engine internals and as my bike frame is back i decided to make a start on the seat pan with my new angle grinder.

First i cut a template out of card
(https://s27.postimg.org/5bdmaeh8z/IMG_0343.jpg)

Then traced it onto some 1.5mm steel sheet
(https://s27.postimg.org/vwl732pxv/IMG_0344.jpg)

And then cut it out. To be fair it was easier than i expected even doing the curve, needs a little tidying up but considering this is the first time I've ever used an angle grinder I'm happy. Just started shaping the rear kick up a little, the metal is easy enough to bend with your bare hands.

(https://s27.postimg.org/wamj2oa1f/IMG_0345.jpg)
(https://s27.postimg.org/51b5o68yb/IMG_0346.jpg)

Like trigger has shown in one of his previous posts i need to make a bracket spanning the frame tubes at the rear to bolt the rear of the seat to and the front.. not sure ye ill have to figure it out. Im thinking about cutting a flap at the front of the seat pan that will bend up and over the rear tank mounting bracket so the seat will sit flush with the tank (thats what that extra tab at the front of the seat pan is for, wanted to make sure i had enough material). Alternatively I could try and shape the metal like this:

(http://i.imgur.com/EokppQu.jpg)
(http://i.imgur.com/8AelNwT.jpg)

Although i not sure i have the skills!

I was hoping to use the same sheet of metal to make the brackets that i need but if i am able to bend it by hand then I'm worried it will bend too easily which will be annoying after I've had it welded and powder coated. What mm thickness would you guys recommend?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 30, 2016, 05:58:08 PM
Little more work on the seat pan today

(https://s23.postimg.org/wqoszluq3/IMG_0348.jpg)
(https://s23.postimg.org/xhhj5dx3f/IMG_0349.jpg)

Might have to change the front a bit as i want a relatively low profile seat and thats as low as i can make it to cover the bracket, not entirely sure how people get around this as some seats look pretty slim

(https://s24.postimg.org/e8m5lx74l/12983189_1028867977149762_7462018353453194274_o.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: mike the bike on December 30, 2016, 07:57:21 PM
How do people manage to ride with those skinny seats, do they put a wodge of foam down their trousers?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on January 01, 2017, 04:53:14 PM
Got some loctite SF 7200 gasket remover stuff to help me avoid damaging gasket surfaces with a razor blade

http://www.loctite.co.uk/loctite-4087.htm?nodeid=8802627944449

Anyone used this before? Apparently it eats paintwork and as I'm not repainting now it's made m a little more reluctant to use it. I suppose I could spray it on and then immediately wipe down painted areas with thinners or maybe spray it onto a rag and rub it on to the gasket surfaces?
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on January 02, 2017, 07:45:48 AM
Try using carb cleaner to soften the gasket, I buy a ton of this from a guy on the market at a pound a tin. You will still need a blade to take the gasket off but, it will be soft.
Title: Re: CB750 Barn find project - First Timer
Post by: Pops400 on January 05, 2017, 09:37:41 PM
How do people manage to ride with those skinny seats, do they put a wodge of foam down their trousers?

 ;D

Big knackers tucked under.
Title: Re: CB750 Barn find project - First Timer
Post by: Pops400 on January 05, 2017, 09:41:56 PM
Please note, the above tip requires balls of steel.

Great thread, BTW.  ;)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on January 07, 2017, 12:56:47 PM
Jut had a little bit of time this morning to finish cleaning up the old sealant off the crank case mating surfaces with that lactate gasket remover stuff i bought.

Takes sealant\old gasket off well but it does affect paint, i knew this so i wiped any overspray off with some thinners but stupidly i didn't realise the inside of the crank cases were painted, i thought they were just discoloured with a gold tinge from 40 years of oil.. some of the overspray has stripped some paint:

(https://s27.postimg.org/nbkz2mjfn/IMG_0363.jpg)
(https://s27.postimg.org/xmxbvab4z/IMG_0364.jpg)

Ive wiped down the inside with thinners but the more that i scratch at the paint thats lifting off the more is coming off.. Im not too worried about having bare metal inside the cases as its going to be coated in oil anyway but should i be worried about more paint flaking off? Anything you guys can recommend?

On the plus side i now have a paint stripper that actually works rather than the eco friendly stuff thats sold nowadays  ;D
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on January 07, 2017, 08:27:42 PM
Hmm this looks especially worrying

(https://s24.postimg.org/8vwuukgyt/IMG_0365.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on January 07, 2017, 08:44:14 PM
They often used paint of various types inside castings to avoid any porosity in the metal allowing the oil to pass through to the outside. Not quite sure of the reasons it's used in these engines but someone else may be able to add more to it.

They were at the time trying to make them as leak free as possible in comparison particularly to British made engines. I guess you'd get too much drop out from production runs to even test them all, so easier to use an oil resilient paint in coating the inside to reach the consistent standard they were aiming for.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on January 08, 2017, 09:27:47 AM
They often used paint of various types inside castings to avoid any porosity in the metal allowing the oil to pass through to the outside. Not quite sure of the reasons it's used in these engines but someone else may be able to add more to it.

They were at the time trying to make them as leak free as possible in comparison particularly to British made engines. I guess you'd get too much drop out from production runs to even test them all, so easier to use an oil resilient paint in coating the inside to reach the consistent standard they were aiming for.

Makes sense I suppose.

My concern is how likely that bubbled paint is to lift off eventually and block oil ways.. maybe I should just strip it all off (well all the stuff that's bubbled anyway)
Title: Re: CB750 Barn find project - First Timer
Post by: hairygit on January 08, 2017, 10:27:55 AM
Personally I would remove the loose/bubbled paint, any solid debris breaking loose inside the motor can cause havoc. Even if it doesn't block the pick up gauze on the pump, do you really want it gunging up the gear clusters and gearbox bearings?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on January 08, 2017, 03:17:07 PM
Personally I would remove the loose/bubbled paint, any solid debris breaking loose inside the motor can cause havoc. Even if it doesn't block the pick up gauze on the pump, do you really want it gunging up the gear clusters and gearbox bearings?

Yeah I don't want to stick it all back together only to shart itself within 5 minutes. I'm going to try and get some sandpaper into the gaps at the front of the upper crankcase and see how easily it comes loose
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on January 08, 2017, 09:42:59 PM
Following on from the above I've given it a good hard scraping with a sharp screw driver and the bubbled paint is absolutely rock hard and definitely doesn't want to come away. It's like the gasket remover has just wrinkled the paint up. If the paint is looking like it wants to stay on could the wrinkled/bubbles paint cause any problems with oil flow where it is (in the recess in front of each cylinder in upper case)?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on February 19, 2017, 11:22:07 PM
Right I'm back home again, got a week off too so I can work on this heap  ;D

Got the crankshaft, gears, countershaft, gear selector bits, kick start and final drive in today. Just need to source an o ring for that dowel thing for the oil gallery at the front of the crank cases and I'll be ready to close the bottom end.

(https://s31.postimg.org/urjm1rcp7/IMG_0435.jpg)

The gear selector gubbins took ages, seem to have them in right now though.

I've used graphogen on the crank and bearing shells, I applied it relatively thick and from just placing the crankshaft into place its oozed out onto the case mating surfaces.. do I only need a thin layer of this stuff? Anything else I need to think about pre lubing?
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on February 20, 2017, 06:20:51 AM
Tat O ring should be 18 x 3
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on February 20, 2017, 11:11:02 AM
Tat O ring should be 18 x 3

Yeah seen, turns out I had been sent a 19x3 by accident
Title: Re: CB750 Barn find project - First Timer
Post by: Niko on February 20, 2017, 01:08:40 PM
Check out a motogadget m unit to simplify wiring as an option


Sent from my iPad using Tapatalk
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on February 21, 2017, 09:10:52 PM
More progress today, closed the cases -

(https://s4.postimg.org/89rewrzxp/IMG_0436.jpg)

And then built up the legal linkage and alternator bits.

BUT

For some reason I've had an absolute nightmare with the clutch cover..

I just can't get the bloody thing on! The dowels are in the crankcase and I can get the right side of the cover lined up but the left side is always too high, it's like the kickstarter shaft is pushing it up too far.

(https://s4.postimg.org/6j8dvaiel/IMG_0437.jpg)

(https://s4.postimg.org/c8omflokt/IMG_0438.jpg)

If I've some how mis aligned it whilst assembling and have to split the cases again I'm not going to be best pleased! Suggestions welcome  ;D
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on February 21, 2017, 09:29:16 PM
Your kick start shaft is too close to the clutch basket. Put the clutch cover on, then the kick start lever, turn the engine with the lever while pulling it back and locate the cover up. If that doesn't work, report back.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on February 21, 2017, 09:43:48 PM
Your kick start shaft is too close to the clutch basket. Put the clutch cover on, then the kick start lever, turn the engine with the lever while pulling it back and locate the cover up. If that doesn't work, report back.

Sweet that sounds easy enough, however my kick start lever is 160 miles away so will have to wait until the weekend when I'm down that way.

I'm in my Mrs' bad books for getting graphogen on the carpet  ;D
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on February 21, 2017, 09:56:05 PM
you also need the shaft holder fitted to the left side, to line up the gear box shaft ;)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on February 24, 2017, 12:43:00 PM
you also need the shaft holder fitted to the left side, to line up the gear box shaft ;)

As soon as the kick start was on I could manoeuvre the spindle easily to get everything lined up :)

Just installing the base gasket (vesrah) and it doesn't quite fit properly. It's the right one but the hole for the camchain is slightly off centre, should I trim a little off to give a little more clearance for the tensioner on the left side or just leave it?

(https://s32.postimg.org/wi0o4o17p/IMG_0442.jpg)
(https://s32.postimg.org/70i9l2jhh/IMG_0443.jpg)

Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on February 24, 2017, 02:42:44 PM
Turn the base gasket over, it should fit better ;)

If you get the rocker cover gasket on the wong way wound  ;D it will leak
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on February 24, 2017, 03:56:24 PM
https://www.cromwell.co.uk/shop/lubricants-and-chemicals/industrial-cleaners-and-solvents/amberclens-anti-static-foaming-cleaner-400ml/p/AMB7010070S?utm_campaign=pla+-+&utm_source=google&utm_medium=shopping-pla&utm_keyword=AMB7010070S&istCompanyId=6aa6787b-063e-4414-802d-129f235df603&istItemId=aqrxtqtxw&istBid=tztt

This is useful for the "Graphogen on the carpet" also for getting the smell of puke out of car interiors if you've transported young children. Although I could see too many occurrences of Graphogen on the carpet leading to  lacking the opportunity of "practicing" for children. ;)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on February 24, 2017, 10:10:21 PM
Turn the base gasket over, it should fit better ;)

If you get the rocker cover gasket on the wong way wound  ;D it will leak

Yeah that got it! Just seemed to me like it should be shined side up..

Got the piston rings on, pistons on the con rods and then with the help of my other half in zero degree temps (I'm back in a garage) we fitted the barrels relatively trouble free (scrimped on ring compressors and just used my fingernails).

I then fitted the head and torqued down, little worried I might have over torqued slightly as my torque wrench seems past it's best.. but it won't be by much so should hopefully be alright. Got the cam towers on and fitted camshaft, just need to set the timing (which involves reattaching the spark advancer - can't remember how it goes on currently!) and then I can fit the rockers and get her all buttoned up.

In other news I had to remove the rotor cover to check the pistons moved fine after fitting the barrels and one of the bolt heads sheared off leaving about 3cm sticking out the case, not a drama as there should be plenty to grip to get out but just a bit annoying.

May have to leave it there for now as I'm being forced to go to a spa tomorrow.. hate that kind of stuff!

https://www.cromwell.co.uk/shop/lubricants-and-chemicals/industrial-cleaners-and-solvents/amberclens-anti-static-foaming-cleaner-400ml/p/AMB7010070S?utm_campaign=pla+-+&utm_source=google&utm_medium=shopping-pla&utm_keyword=AMB7010070S&istCompanyId=6aa6787b-063e-4414-802d-129f235df603&istItemId=aqrxtqtxw&istBid=tztt

This is useful for the "Graphogen on the carpet" also for getting the smell of puke out of car interiors if you've transported young children. Although I could see too many occurrences of Graphogen on the carpet leading to  lacking the opportunity of "practicing" for children. ;)

Cheers bro but brake cleaner got it in the end!
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on February 24, 2017, 10:56:18 PM
Hope you cross hatched the bores, otherwise it will smoke like a chimney  ;D ;D
Title: Re: CB750 Barn find project - First Timer
Post by: mike the bike on February 24, 2017, 11:25:32 PM
I would have thought the super slippery stuff in the Graphogen would find its way into the clutch and make that super slippery, or am I over thinking again?
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on February 25, 2017, 06:57:51 AM
I would have thought the super slippery stuff in the Graphogen would find its way into the clutch and make that super slippery, or am I over thinking again?

A bit like oil is slippery Mike  ;D You only use a wipe of Graphogen... not the whole tube. The tube it comes in is trade use, the new company owners have said, they will start doing smaller tubes soon.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on February 25, 2017, 10:45:47 AM
Hope you cross hatched the bores, otherwise it will smoke like a chimney  ;D ;D
Well I had them honed if that's what you mean?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on March 02, 2017, 07:37:51 PM
Just waiting for a new torque wrench to arrive as I expect my current one has had it.

Am I likely to run into leaky head gasket issues if I end up backing off a few of the fixings, it's probably not massively over tightened but I don't want to warp anything..
Title: Re: CB750 Barn find project - First Timer
Post by: mike the bike on March 02, 2017, 07:58:51 PM
Got some Graphogen and plastigauge.   Going to do a proper job this time.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on March 05, 2017, 09:33:26 PM
Just waiting for a new torque wrench to arrive as I expect my current one has had it.

Am I likely to run into leaky head gasket issues if I end up backing off a few of the fixings, it's probably not massively over tightened but I don't want to warp anything..

Anyone able to advise on this?
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on March 05, 2017, 09:45:31 PM
Reverse torque pattern about quarter of a turn and then re torque.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 11, 2017, 04:23:50 PM
After another busy spell at work I've got the next 10 days to do a bit of work on the bike. I'm currently in the process of buying a house which is seriously eating up all my money so will just be doing what I can for now. Unfortunately I can't afford to get bits powder coated right now so reassembly may still be a way off.. but I'll get there!

As far as I remember, when I left the lump I had the cylinder head on but hadnt got the cam shaft on properly as I didn't have the contact breaker assembly on to mark the timing. It's been a while now since I took it apart - how the heck does this go back on??

Just as a look forward I'm trying to tally up future costs to help me budget, I'd like the wheels to be powder coated satin black (spokes and all). Is this finish likely to damage when adjusting the spokes?
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on April 11, 2017, 04:28:57 PM
you need to powder coat after truing/building the wheels or it will crack when you attempt to mtighten a spoke
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 11, 2017, 04:32:50 PM
you need to powder coat after truing/building the wheels or it will crack when you attempt to mtighten a spoke

Hoping this wouldn't be the answer  ;D
So does this mean fitting tyres, truing wheels (would they also need balancing or does the truing negate this?) then stripping the tyres back off, powder coating as a single piece then refitting tyres?

Edit:

Does anywhere sell black spokes? Would be a lot easier to get some which are either factory powder coated or anodised black
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 11, 2017, 09:24:54 PM
As far as I remember, when I left the lump I had the cylinder head on but hadnt got the cam shaft on properly as I didn't have the contact breaker assembly on to mark the timing. It's been a while now since I took it apart - how the heck does this go back on??

Anyone able to help with this?
Title: Re: CB750 Barn find project - First Timer
Post by: hairygit on April 11, 2017, 09:39:46 PM
What instructions do you need, the timing unit or re timing the camshaft?

Sent from my X6pro using Tapatalk

Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 11, 2017, 11:10:08 PM
What instructions do you need, the timing unit or re timing the camshaft?

Sent from my X6pro using Tapatalk

Reassembling the timing unit. Doesn't seem to be featured in any of the manuals I've got
Title: Re: CB750 Barn find project - First Timer
Post by: hairygit on April 11, 2017, 11:11:46 PM
Did you just remove it from the engine, or dismantle it as well?

Sent from my X6pro using Tapatalk

Title: Re: CB750 Barn find project - First Timer
Post by: DaveB on April 12, 2017, 11:41:40 AM
What instructions do you need, the timing unit or re timing the camshaft?

Sent from my X6pro using Tapatalk

Reassembling the timing unit. Doesn't seem to be featured in any of the manuals I've got

This video might help?

https://www.youtube.com/watch?v=InPZuM_K9kY

Regards,
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 12, 2017, 02:18:53 PM
What instructions do you need, the timing unit or re timing the camshaft?

Sent from my X6pro using Tapatalk

Reassembling the timing unit. Doesn't seem to be featured in any of the manuals I've got

This video might help?

https://www.youtube.com/watch?v=InPZuM_K9kY

Regards,

Yeah looks easy, not sure why I had a spastic moment there.. was probably running low on coffee at the time.

As a look forward I've got some quotes for powdercoating, there's basically 2 which look good and aren't too far from a route I often travel (there's not much local to me.

The first is PCL powder coating in Bridgewater

https://m.facebook.com/PCL-Powder-Coating-340782079286190/?ref=page_internal&mt_nav=1

They said a medium to large frame would be around £160-170 inc blasting etc which is a little more than I was expecting. I asked them about spoked wheels and they said the can do them delaced or as a single unit for £55/wheel provided the chrome is in ok nick.

Secondly I called Perfectadent in Bridgend.

https://en-gb.facebook.com/Perfectadent/

They said a frame is £100+VAT which is reasonable, I asked them about spoked wheels and he said they can do them as a single unit but they don't offer a warranty on the spokes as they said it can be hit or miss how long the coat lasts. He recommended sourcing some black spokes.

To be fair it made sense what the guy at perfectadent said so I may go down that route. Looking at their FB page they do a lot of frames etc.

Does anyone know where I could get the right sized spokes in black??
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 13, 2017, 01:41:30 PM
Got the timing all squared away earlier today

(https://s21.postimg.org/thhqr4lgn/IMG_0584.jpg)
(https://s7.postimg.org/c84arol3v/IMG_0585.jpg)

Annoyingly I've just noticed that the cam tower for cyl 1&2 is significantly damaged on exhaust side  :( all the others look fine and the rocker spindles all look good. I remember when I was taking the top end apart following a rubbish Haynes manual I've got it never mentioned backing the tappets out before removing the spindles and in my noobness I just tapped the spindles out with a screwdriver and hammer (well as far as I can remember that was the only one which needed it). Must have damaged it in the process as there's no corresponding wear on the spindle.

(https://s7.postimg.org/6xzc0e0uz/IMG_0586.jpg)

Annoyed is an understatement but everything's a learning curve for me.
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on April 13, 2017, 02:12:11 PM
That is a easy repair  ;)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 13, 2017, 02:29:38 PM
That is a easy repair  ;)

As in just sand it smooth??
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on April 13, 2017, 02:44:28 PM
Trig says just remove the burr with a sharp instrument, and then use a very fine wet and dry around a dowel. Trig would ream it.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 13, 2017, 03:18:48 PM
Trig says just remove the burr with a sharp instrument, and then use a very fine wet and dry around a dowel. Trig would ream it.

Sweet, I'll give it a go
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on April 13, 2017, 06:31:38 PM
Shaft does't turn in there anyway so as long as its a decent load surface it's OK
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 13, 2017, 07:18:42 PM
Shaft does't turn in there anyway so as long as its a decent load surface it's OK

Yeah only just realised that! I though the shaft turned in the cam towers rather than the rocker arms turning on the shaft   ;D

Sanded it down anyway and it's all smooth now.

Assembled the rocker arms no problem and then came across a baggy of 8 little metal 12mm cylinder pin things suspiciously like the ones that go between the cylinders and head.. doh! Definitely not ideal going so long between stripping and reassembling.

I remember installing the 8 rubber bits (which sit around the metal pins) and remember thinking at the time they seemed a bit loose just sitting there..

How much of a risk is it to leave as is? What's the purpose of the metal pins?

I have the creeping feeling the head is about to come off again!

EDIT: seems these metal pings weren't present until the K3, probably missed them out as I was following hondaman shook where he rebuilds an earlier bike.
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on April 13, 2017, 08:47:26 PM
Honda didn't put them there for no reason, looks like the head is coming off again as it's not an earlier head. :'( :'( :'(
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 13, 2017, 08:50:41 PM
Honda didn't put them there for no reason, looks like the head is coming off again as it's not an earlier head. :'( :'( :'(

Haha oh dear. Is that another new head gasket too then?
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on April 13, 2017, 08:52:58 PM
Which type did you use?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 13, 2017, 08:59:26 PM
Which type did you use?

Vesrah, its a relatively thick matted metal fibre looking one

Edit:

This one
http://4into1.com/vesrah-cylinder-head-gasket-hg-1022-honda-cb750-1969-1978/
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on April 13, 2017, 09:01:25 PM
You can use that again  :D
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 14, 2017, 04:32:54 PM
Well got things sorted today, wasn't too bad apart from one for some reason I can't get a 10mm socket onto one of the 6mm head bolts (all the other were fine, think it's just the casting of the head itself stopping it) and ended up rounding it out with PD3..

Had to drill the head off the sucker to pull the cylinder head and then it came out easy. Tried for ages with an impact driver but it just mullered it.

Got those pesky pin things in and bolted everything back up, cam towers back on, cam on and timing set. Just need to build the rocker arms up and I'm back to where I was yesterday.


head off with the missing pins
(https://s27.postimg.org/ivq2a67n7/IMG_0590.jpg)

The bolt that didn't want to play fair
(https://s27.postimg.org/x3fqytkc3/IMG_0592.jpg)

Lucky I had a spare knocking about so could get it back together right away
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 15, 2017, 08:08:43 PM
Had another couple of house in the garage today with a stinking hangover.

Top end is all buttoned up now which is pretty satisfying.

(https://s14.postimg.org/3o2ydbkip/IMG_0600.jpg)

Question - the oil pressure sensor, is it supposed to screw all the way in? Mine seems to bottom out with a mil or so gap. Also is it worth using a bit of honda bond on this as it previously had something on it when I removed it.

(https://s14.postimg.org/fr8a0vvkx/IMG_0601.jpg)

I need to figure out how my seat pan rear mud guard is going to bolt up so I can fab the brackets up and get the frame to the powder coaters. Basically I'm going to cut my rear guard down so it looks something  like this:
(http://thebikeshed.cc/wp-content/uploads/2016/05/cb750-2.jpg)
 
Which will mean I need to have a bracket here which I can use to bolt both the rear of the seat pan and cut down mud guard to. Will keep the plastic liner thing too if I can

(https://s14.postimg.org/sjwe0t76p/IMG_0602.jpg)

I need to get the wheel back on to be fair so I can properly see how it's going to look. Only thing I'm concerned about is how securely the mud guard will be attached by just two bolts.. might get some up and down movement as the metal is only thin. Also it might me a bit on the low side as the one in the picture I posted seems much more tucked up. Perhaps the seatpan on that bike has an arched section to allow this?

Also did a little more work on the seatpan today and made a curved section to nicely cover the rear tank mount, just need to get it welded on. I think I'm going learn to weld soon as it's so annoying having to rely on someone else. Still unsure how the front of the seatpan will mount to the frame as I'm keeping the battery holder and tool tray underneath so there's not going to be much space

(https://s14.postimg.org/ddqc9vh5t/IMG_0604.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 16, 2017, 01:14:51 PM
Remade the little hump for the seat pan today as I wanted to keep it as low as possible which meant I needed a 'longer' hump. Only actually ended up slightly lower but I want a thin seat.

(https://s9.postimg.org/n3yku2gnj/IMG_0605.jpg)

(https://s9.postimg.org/x2jjgjq33/IMG_0607.jpg)

Hopefully the welder can fill in any small gaps for me as it doesn't sit perfectly flush.

Been thinking about how I want the read end to look. As it is now the rear mudguard will sit a little bit low for my liking:

(https://s9.postimg.org/kcfb3gi4v/IMG_0608.jpg)

I'd quite like it to be tucked up as so:

(https://s9.postimg.org/k0xuqp1ov/IMG_0611.jpg)

Which would mean he seat pan would need to have a hump on the rear of it to accommodate the intruding mudguard. I don't think I have either the tools or skill to do this, and I'm also unsure how uncomfortable it would be for a passenger with basically a thin layer of foam covering it..but I'm going to put some more thought into it and maybe see if there a local fabricator who I could use.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 17, 2017, 05:54:44 PM
Mocked the back end up to check clearance.

(https://s1.postimg.org/uwqhy74mn/IMG_0612.jpg)
(https://s1.postimg.org/g21wk0v1r/IMG_0613.jpg)
(https://s1.postimg.org/tmsoj5aun/IMG_0616.jpg)
(https://s1.postimg.org/fiwtar3n3/IMG_0618.jpg)

Got a couple of inches above the wheel and an inch or so clearance in front:

(https://s1.postimg.org/93xse2wxb/IMG_0617.jpg)

I've got some Hagen shocks with adjustable dampening that I'll use but they are the same length as standard shocks. What's the least amount of clearance I can get away with?

Title: Re: CB750 Barn find project - First Timer
Post by: captaink on April 17, 2017, 05:59:29 PM
Should look pretty mean when its finished.
Reminds me of Sons of Anarchy
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 17, 2017, 08:16:31 PM
Should look pretty mean when its finished.
Reminds me of Sons of Anarchy

I'll just be pleased if it get finished to be fair!  ;D Its challenging learning as I go but I enjoy it a lot and I don't think it will be my last.

Just had a thought - if I get my new shocks on there with the springs removed I'll be able to simulate it bottoming out and see if the tyre hits anything.

The easier alternative would be to mount the tail light above the side mounted number plate as I already have this mount:

https://www.amazon.co.uk/Prison-Motorbike-Motorcycle-Number-License/dp/B00Y16L134
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 18, 2017, 03:04:13 PM
Took he springs out my Hagen shocks to see if they would bottom out before the tire hits anything, no suck luck, still got an inch or so to go.

(https://s7.postimg.org/998nbekdn/IMG_0628.jpg)

Might get away with it if I have he dampening on it's hardest setting and if not I can just source some slightly longer shocks.

Took the frame to a relatively local place to see if they could fab up the 2 brackets I need to hold the mud guard in place and showed them how I wanted it to look.. he guy basically told me hey charge £45/hour and it could run into a few hours fettling bits about so I didnt bother.

Had a fastball from work as well today which means I'll be very busy for the next 9 months so this is going to have to take (yet again) a back seat  :(

Plan is now to purchase a welder and learn to do things myself, so if anyone is selling one please let me know  ;D

Title: Re: CB750 Barn find project - First Timer
Post by: MrDavo on April 18, 2017, 04:43:13 PM
Question - the oil pressure sensor, is it supposed to screw all the way in? Mine seems to bottom out with a mil or so gap. Also is it worth using a bit of honda bond on this as it previously had something on it when I removed it.

Definitely no, don't screw it all the way in. I'm not sure what it is about the thread, as it doesn't bottom out against anything as far as I know, but someone on here (or maybe .net in the USA) b*ggered up their cases big time by doing this, there's a taper at the end of the thread, after a poster had tightened it up all the way, then a nip to make sure it didn't work loose, he noticed the crankcase was cracked.  :o .

If both threads are OK there's no reason why you should need to use sealant, and if you get any of it in the oil gallery it could kill your cam by blocking the cam oil feed in a driiling somewhere where you can't ever find it.
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on April 18, 2017, 05:08:33 PM
Thread is N(ational)P(ipe)T(aper) NPT and designed to get tighter as it screws in so DO NOT attempt to Bottom the fitting
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on April 18, 2017, 05:29:34 PM
Longer shocks effect the front end handling big time.
Are you sure you want to use that chrome rear, there are many different ones on the market.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 18, 2017, 09:29:34 PM
Longer shocks effect the front end handling big time.
Are you sure you want to use that chrome rear, there are many different ones on the market.

Never really considered anything else as I just have this to hand, plus all the ones on eBay look terrible. Was going to sand it down to give it a brushed look

Any suppliers you recommend? I might as well have a look
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on April 18, 2017, 10:33:05 PM
I don't think the rear guard in the bike shed picture is a SOHC one, looks smaller. I am also a little surprised that I can't find any details on the build of the bike.
Title: Re: CB750 Barn find project - First Timer
Post by: Mag1 on April 18, 2017, 10:38:09 PM
Underdog, have a look at the pics i uploaded in the newbies where I was doing what you are currently doing 10 months ago. I tried with oversize rear mudguard but was too big, in the end went with purchasing mangled front mudguard and cut to size, this way you have extra clearance and also easier to attach tabs to. One thing to muck up now is your seat fixings and more importantly access to fix your seat down either by bolts/wing nuts or hinged. Your right to stay away from welding shops unless they know what they are doing, due to hourly rates and finding a solution for you. Best to look on all forums and Google pics for ideas. If I could and roll back time is weld hinges to the frame and bolt that to my seat, but heyho. As trigger has said also, don't raise the rear end this will upset the geometries / effect steering and ride ability. Enjoy
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 19, 2017, 09:38:10 PM
I don't think the rear guard in the bike shed picture is a SOHC one, looks smaller. I am also a little surprised that I can't find any details on the build of the bike.

The bike was built by redeemed cycles, he's done a few really cool old SOHCs

https://en-gb.facebook.com/RedeemedCycles/

Here's a pic of the high sort of shows the mudguard a little better. Perhaps he had just cut the front half off..?

(https://s18.postimg.org/qeqr9or61/IMG_0629.jpg)

He was able to get more clearance because his rear hoop has a much steeper angle, something I failed to consider earlier on.

I may just do something  like this:

(https://s18.postimg.org/f3o3lbkax/IMG_0126.jpg)

As I have a side mount number plate holder which I can attach a tail light to, not sure on the legalities though.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 19, 2017, 11:00:19 PM
Underdog, have a look at the pics i uploaded in the newbies where I was doing what you are currently doing 10 months ago. I tried with oversize rear mudguard but was too big, in the end went with purchasing mangled front mudguard and cut to size, this way you have extra clearance and also easier to attach tabs to. One thing to muck up now is your seat fixings and more importantly access to fix your seat down either by bolts/wing nuts or hinged. Your right to stay away from welding shops unless they know what they are doing, due to hourly rates and finding a solution for you. Best to look on all forums and Google pics for ideas. If I could and roll back time is weld hinges to the frame and bolt that to my seat, but heyho. As trigger has said also, don't raise the rear end this will upset the geometries / effect steering and ride ability. Enjoy

Yeah I like how you did yours actually, you just seem to have way more clearance at the back end than me somehow?
Title: Re: CB750 Barn find project - First Timer
Post by: Mag1 on April 19, 2017, 11:47:43 PM
I used a 40mm upswept hoop, made an extra frame support just where the hoop starts to upswept, basically 40mm wide 4mm thick flat bar and welding that in place inside of the rear end, but level to the top of frame. This enabled me to weld on a tab slightly upswept to fit the fender. With the fender cut I used the mudguard hoop that attaches to the mudguard and forks, cut to size and welded that to the underside of the seat hoop to act as more robust fixing point to install the mud guard as it has 2 small bolts and is already shaped to the mudguard. Will take a close up photo and post up this weekend. The picture will show more than I explain.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 20, 2017, 11:52:07 AM
I used a 40mm upswept hoop, made an extra frame support just where the hoop starts to upswept, basically 40mm wide 4mm thick flat bar and welding that in place inside of the rear end, but level to the top of frame. This enabled me to weld on a tab slightly upswept to fit the fender. With the fender cut I used the mudguard hoop that attaches to the mudguard and forks, cut to size and welded that to the underside of the seat hoop to act as more robust fixing point to install the mud guard as it has 2 small bolts and is already shaped to the mudguard. Will take a close up photo and post up this weekend. The picture will show more than I explain.


Yeah mate any more pictures would be really helpful. Still can't work out how you've got so much clearance at the rear end, perhaps your hoop is slightly longer than mine? On standard length wagon shocks my tyre with be rubbing hoopage and still be an inch from bottoming out.

Thinking about it surely using the front mud guard rather than the rear will mean less clearance.. as its narrower so the edges of the tyre will foul when theres still space above the tyre?

The tabs you welded for the front of the seat pan, do these get in the way of taking the battery in and out? i was thinking about drilling the threaded holes for the front of the battery tray and tool tray right through the frame and using those
Title: Re: CB750 Barn find project - First Timer
Post by: Mag1 on April 20, 2017, 06:12:43 PM
The tabs I welded in at the battery box are more as a guide for the seat bolts to stop it moving around while riding, the rear is where I attach the seat and bolt into place. The battery and tray do fit in but it's a tight fit, but works for me. Will take some pics for you whereby hopefully you will work out what works for your seat pan and mud guard. For some reason the front fender works for me, I was thinking what would fit in there as I needed something to give some protection from water spray and any flying debris from the tyre. I did think leaving open, but looks better filled with the fender, and attach the rear light also. If your building your own seat pan what do you intend to use for fixing in place?. If I could turn back time I would weld in m8 or m6 nuts to the top side of the pan and use bolts, or find place to have it hinged and lockable. I know for next time!!
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on April 20, 2017, 09:34:38 PM
The tabs I welded in at the battery box are more as a guide for the seat bolts to stop it moving around while riding, the rear is where I attach the seat and bolt into place. The battery and tray do fit in but it's a tight fit, but works for me. Will take some pics for you whereby hopefully you will work out what works for your seat pan and mud guard. For some reason the front fender works for me, I was thinking what would fit in there as I needed something to give some protection from water spray and any flying debris from the tyre. I did think leaving open, but looks better filled with the fender, and attach the rear light also. If your building your own seat pan what do you intend to use for fixing in place?. If I could turn back time I would weld in m8 or m6 nuts to the top side of the pan and use bolts, or find place to have it hinged and lockable. I know for next time!!

Yeah I was going to go for welded m6 bolts on the top of the seat pan like you said.
I'm not going to be working on the bike again for a while so will have a good think. May even re work the rear hoop with a steeper angle to give more clearance
Title: Re: CB750 Barn find project - First Timer
Post by: Mag1 on April 24, 2017, 09:35:34 PM
here are pics as promised, this is how i mounted the fender
Title: Re: CB750 Barn find project - First Timer
Post by: Mag1 on April 24, 2017, 09:37:09 PM
last one, if have any questions let me know.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 13, 2017, 05:18:24 PM
Yeah I was going to go for welded m6 bolts on the top of the seat pan like you said.
I'm not going to be working on the bike again for a while so will have a good think. May even re work the rear hoop with a steeper angle to give more clearance

Been super busy with work over the last few months and also bought and moved into a new house. Finally got a decent sized garage/workshop to use.

Decided to rework the rear hoop so bought a welder, learnt how to use it and did this this morning:

starting point-

(https://s3.postimg.org/m6wnuh2b7/IMG_0604.jpg)

(https://s3.postimg.org/dort3vl6b/IMG_0814.jpg)

(https://s3.postimg.org/a6ft7hkab/IMG_0813.jpg)

(https://s3.postimg.org/7ozgmhb03/IMG_0815.jpg)

(https://s3.postimg.org/c8galqi9f/IMG_0819.jpg)

(https://s3.postimg.org/uy8a2hb03/IMG_0820.jpg)

(https://s3.postimg.org/rdcej96gj/IMG_0822.jpg)

(https://s3.postimg.org/ih1mfbfub/IMG_0827.jpg)

(https://s3.postimg.org/lwp5b4noz/IMG_0824.jpg)

First thing I've welded in anger and pretty happy how its turned out. Should give the clearance i need at the back end.

Just need the rear mudguard bracket and it can get powdercoated.

Whats the best way to remove the frame/ model no. plaque thats riveted on? drill it out?
Title: Re: CB750 Barn find project - First Timer
Post by: Mag1 on August 13, 2017, 10:19:16 PM
Very nice handy work, and welcome back. You need to watch how you remove the vin plate, it's soft alloy plate, I think the rivets are brass?, it's also glued on the back. I just levered mine off with care, but it still split at the ends, but it's ok. Just stuck it back on using arodite.

What's next fender?.

Been off a while also, had to have a break away from the bike as it was doing my head in and started to hate it. But back on it now so get it finished.

Good luck, if you have any Q's fire away.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 13, 2017, 10:46:39 PM
Very nice handy work, and welcome back. You need to watch how you remove the vin plate, it's soft alloy plate, I think the rivets are brass?, it's also glued on the back. I just levered mine off with care, but it still split at the ends, but it's ok. Just stuck it back on using arodite.

What's next fender?.

Been off a while also, had to have a break away from the bike as it was doing my head in and started to hate it. But back on it now so get it finished.

Good luck, if you have any Q's fire away.

Cheers bud, my first time welding anything other than runnin beads on a steel sheet, can't believe I payed a professional welder £130 to weld the original hoop on (that I provided!). My welder cost £150 and now I've added another string to my bow.

Just to clarify about the vin plate, are you saying you levered it off without drilling the rivets out first?
Title: Re: CB750 Barn find project - First Timer
Post by: JamesH on August 14, 2017, 09:31:24 AM
On the VIN plate. Drill the rivets out first, then get some very thin metal wire and try and 'cut' the adhesive backing off behind the vin plate using the profile of the headstock to avoid damage to the vin plate...worked well for me (after I botched a K0 vin plate first time round duh...).
Title: Re: CB750 Barn find project - First Timer
Post by: paul G on August 14, 2017, 12:24:11 PM
On the VIN plate. Drill the rivets out first, then get some very thin metal wire and try and 'cut' the adhesive backing off behind the vin plate using the profile of the headstock to avoid damage to the vin plate...worked well for me (after I botched a K0 vin plate first time round duh...).

You could also try the first part of the above with the rivets and then a hair dryer on the plate to get some heat in it.
This sofens the adhesive so you can get it off.
Always worked for me.

Regards,
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 14, 2017, 04:18:05 PM
Great to see you back building Phil. I love this thread of yours.
Title: Re: CB750 Barn find project - First Timer
Post by: Mag1 on August 14, 2017, 06:08:58 PM
Only other suggestion would be to remove the rivets, then heat up the plate with hairdryer, once heated up strip some old electrical wire and use in a sawing action behind the vin plate through the glue, keeping the wire tight to the frame. May work?.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 09, 2017, 09:20:48 PM
Made some mounts for the mudguard today. Managed to get the look I wanted.

(https://s26.postimg.org/vzzss1jfd/IMG_0851.jpg)
(https://s26.postimg.org/q0c1odymx/IMG_0852.jpg)
(https://s26.postimg.org/4f6z0s1w9/IMG_0853.jpg)

Not got my oil tank or battery tray at my house currently so need to check there's no interference - little worried about the oil tank not fitting properly now..

If needed I'll cut the mudguard down and move the brackets.

Almost ready for paint (after I've made some new seat pan mounts) now just need to make sure I haven't overlooked anything. If anyone spots something then please pipe up!
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 15, 2017, 08:53:57 PM
Well the oil tank and battery tray fit with about 1mm clearance so happy with that! Had a go making a new seatpan up today by forming the 1.2mm steel sheet with a hammer, didn't go brilliantly as I think it's a bit thick.

Will just have to make it in sections and weld together
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on September 15, 2017, 09:21:41 PM
I will be interested to see how you get on with your seatpan as I'm just about to start making one for my CB550 custom. I haven't got a clue where to start!!
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 09, 2017, 05:29:59 PM
Finally got the seatpan figured out. I’ve been scratching my head over how I could get the clearance for the rear mudguard/rear wheel whilst still being able to securely mound the seatpan both front and back. After a few different ideas (some of which could have worked if I was better at metal forming/ had the right tooling) I decided to create a flat seatpan with a kick up to match the rear hoop, then remove a circle of metal where the mud guard needed clearance and weld on another section of metal to form a cavity. Seems to simple!

Ready to be welded up:
(https://s7.postimg.org/9wi435x6z/9_F6_AA4_EA-57_B4-4101-_AF3_F-11_B57_AC2_B9_D4.jpg)

All done:
(https://s7.postimg.org/7f6cvx0fv/4_D11_F91_C-099_D-4_C1_C-9_EE7-4117_DA0_A4_CFB.jpg)

(https://s7.postimg.org/phzfn4okr/5_D06_E5_F1-_CDB8-4_EC5-_B756-17_C62_D85_A2_AE.jpg)
Not my neatest welding but it’s all going to be hidden away anyway.

Need to make a little bracket to mount my reg rec on the battery tray and it can all go get powder coated (pending not being skint that is).

I’m going to get my seat professional upholstered, but is it worth giving the foam work a bash myself? In my head I can just layer some close cell foam on top with glue and then carve into shape.

Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on December 09, 2017, 06:26:41 PM
What metal and what thickness is the seat pan please?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 09, 2017, 06:57:54 PM
What metal and what thickness is the seat pan please?
Its 1.2mm mild steel. Just looks shiny as it’s been wire brushed
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on December 09, 2017, 07:07:35 PM
What metal and what thickness is the seat pan please?
Its 1.2mm mild steel. Just looks shiny as it’s been wire brushed
Great, thanks. I know you are going to get it covered professionally but do you know how he is going to attach the cover to the base on the underside?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 09, 2017, 07:13:57 PM
What metal and what thickness is the seat pan please?
Its 1.2mm mild steel. Just looks shiny as it’s been wire brushed
Great, thanks. I know you are going to get it covered professionally but do you know how he is going to attach the cover to the base on the underside?

I’d imagine either rivets orncover the whole thing like a sleeve. That’s upholsterer perks though 👍
Title: Re: CB750 Barn find project - First Timer
Post by: Laverda Dave on December 10, 2017, 11:44:45 AM
Nice job Underdog, that's the fun of building a special, the working out of how to overcome problems and the satisfaction that comes with it when you do :)
I think you have mixed up an upholsterer with a Coach Trimmer though. An Upholsterer makes sofa's and dining room chairs, a Coach Trimmer make vehicle seats, carpets, headlinings, motorcycle seats etc.  I'm only saying this because I used to be a Coach Trimmer back in the day (wish I was still doing it, and still have all my tools and sewing machine in the loft!)  ;)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on December 14, 2017, 04:28:18 PM
Sorted out the mount for my solid state reg/rec

Cut the brackets for the old reg and rec off and decided I was going to mount it here
(https://s7.postimg.org/n6wd91jvv/EDA3_D623-_E1_FF-4_F36-9043-24_C0_F1_F35_C7_A.jpg)

Put my ‘new’ bench drill to good use (it’s actually almost 70 years old!)

(https://s7.postimg.org/vcef795kr/8_C545_B55-_AF17-4_CFB-_A018-48_D4_FC7_A58_EA.jpg)

Welded some bolts through from the other side

And voila!
(https://s7.postimg.org/qdqwsp6wr/3_A2_B680_A-2387-431_B-877_E-4507_D10_F8_E7_E.jpg)

I can’t remember what this little bracket with a hole in is for so I left it on for now, any ideas?
(https://s7.postimg.org/xgys8bk23/24293_CF3-_EB41-4305-8_C51-_B172_F5049_F3_D.jpg)

Heard back from some automotive trimmer re getting my seat done.. £185 :o
Title: Re: CB750 Barn find project - First Timer
Post by: Mag1 on January 07, 2018, 09:14:02 PM
Looking good this is. Nice work indeed
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on May 27, 2018, 09:31:40 PM
Picked up the tools today again.

Going to get all the bits to the powdercoaters tomorrow (if he's open), but i.m struggling getting the bushes for the shocks out the swingarm.

(https://s33.postimg.cc/6sjm4c9i7/IMG_1699.jpg)

(https://s33.postimg.cc/630trytj3/IMG_1698.jpg)

So one side i tried the ole threaded rod and socket trick to pull it out but the outer was stuck fast and remained in the swing arm. The other started going that way too so i tried to crimp the edges in a bit with a chisel but it won't budge.

Plan B is to cut it with a hacksaw and bash it out with something, any other methods worth trying first?


Stripped the wheels down today, managed to get the old tyres off in my garage with none of the correct tools.. wouldn't recommend it! Have ordered new spokes and cush drive bits to build them back up. Rims and hubs are going satin black, would like the spokes black too but they are expensive so have opted for a cheap stainless set from DS.

Still open to suggestions on where to get black spokes at a decent price as i can always cancel/ return the DS ones

Title: Re: CB750 Barn find project - First Timer
Post by: Deano400 on May 27, 2018, 09:49:09 PM
Used the hacksaw method on mine, two cuts. There is advice on here but I can't remember who posted it. With two close cuts removing a thin strip the rest came out easy.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on May 28, 2018, 11:47:58 AM
Done a little research on how i can turn the spokes black, im reluctant to powder coat them loose as i think ill run into problems with them fitting through the hubs and flaking off around the threaded ends.

Best way seems to be gun blue which was developed to give steel a black oxide finish (originally on weapons hence the name). The spokes I've got are these from DS:

https://www.davidsilverspares.co.uk/CB750K6-FOUR-1976/part_105494/

Doesn't specify that they are zinc coated but i presume they are as surely they would advertise if they were stainless.. Plan is to use muriatic acid to remove the zinc coating and then use this:

https://www.amazon.co.uk/Birchwood-Casey-Liquid-Shotgun-Blueing/dp/B0091C0LBQ/ref=sr_1_4?s=sports&ie=UTF8&qid=1527504245&sr=1-4&keywords=gun+blue&dpID=41Qlxi9xPNL&preST=_SY300_QL70_&dpSrc=srch

Watched a few youtube videos and the process is simple. Probably the process which Central wheels uses to 'chemically blacken' their spokes that they sell for £100+

The muriatic acid shouldn't react with the steel beneath the zinc coating on the spokes so shouldn't weaken them at all. Will report back with results.

Edit: seems the black oxide only has limited rust protection, apparently the gun blue works on zinc alloys so might work with the coating left on. Other option would be to coat them with boiled linseed oil
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on May 28, 2018, 11:56:18 AM
Take the spokes to a platter and have them black zinked  ;)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on May 28, 2018, 12:00:39 PM
Take the spokes to a platter and have them black zinked  ;)

admittedly this would be a lot easier but presumably more costly? Ill look into it any way
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on May 28, 2018, 03:48:15 PM
Used the hacksaw method on mine, two cuts. There is advice on here but I can't remember who posted it. With two close cuts removing a thin strip the rest came out easy.

This worked well btw
Title: Re: CB750 Barn find project - First Timer
Post by: Woodside on May 28, 2018, 05:42:48 PM
caswell uk do a steel blackening chemical im pretty sure.
give them a call
Title: Re: CB750 Barn find project - First Timer
Post by: Woodside on May 28, 2018, 05:44:38 PM
edit
caswell europe...

www.caswelleurope.co.uk/for-mild-steel/
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 02, 2018, 12:48:55 PM
Decided black spokes aren’t worth the bother, I just won’t clean them so they will look black anyway  ;D

Took the frame, wheel rims and hubs, seatpan, a load of rear brake hits, engine mount brackets, wheel brace, fork lowers, steering stem, triple tree, swing arm, battery box and loads of other misc bits to the powder coaters today. He said even though the chrome bits will be a pig he will do it all for £220. Well happy with that, especially as he is 5 minutes down the road from me.

Was looking through the boxes of bits I have and it’s been so long since I stripped the old girl down I don’t recognise half of it, at least I sandwich bagged most of it and vaguely labelled it up.

Looking forward for it to start resembling a motorbike again. Trying to avoid buying an old enduro bike that’s cropped up local as I don’t need one, it will eat up my spare time and cash.. but it would be a right laugh!
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on June 02, 2018, 12:56:16 PM
If your powder over chrome, the paint will peel off in time. They need to be de chromed first.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 02, 2018, 01:03:18 PM
If your powder over chrome, the paint will peel off in time. They need to be de chromed first.

yeah thats what he meant when he said the chrome rims are a pig to powder coat as stripping the chrome is difficult, but said he has done it before with good results
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 03, 2018, 04:19:26 PM
Have ordered some TT100 tyres and some progressive fork springs from hagon. Basically just need the bits back from the painters and i can get things reassembled.

Had a manual clean out of the carb bowls a while back but need to do a more in depth clean, thinking abut buying a small (2l) ultrasonic cleaner, they have them on amazon for <£40. Also going to up the main jets from 105 to 110 and idle jets from 40 to 42 as the 4 into 1 system going on is basically straight through and im going to be running pod filters (because i never want my bike to run well again).

Anyone got any guides bookmarked on carb cleaning?

Wheres a good place to get the jets from?

EDIT just seen my cruzin image carb rebuild kit came with 110 mains so just need the idles
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 05, 2018, 10:48:18 AM
Bits have started arriving

TT100s:
(https://s33.postimg.cc/r3pmpfov3/IMG_1713.jpg)

Hagon springs and 20L of vinegar to pickle my fuel tank in:
(https://s33.postimg.cc/hvxe8xcpr/IMG_1714.jpg)

Unfortunately they've sent me a 3.50 19 front rather than the 4.10 i ordered but the wheels aren't good to go yet anyway, spoke to them this morning and the replacement will be here tomorrow. Have gone mad ordering all the bits i need to finish the bike, yet to be delivered is:

ultrasonic cleaner and carb solution
Short reverse cone for my MAC 4-1 system
Mini tacho
Mini speedo with LED idiot lights
Some different size jets
Vinyl leather stuff and foam to build the seat
New wheel spokes
and a few other misc bits.

I think all i need is a new chain and sprockets, possibly new points (may try and reuse the old ones), new brake hoses (looking to get some braided ones made up that go straight into the caliper - anyone know of any suppliers?) and some carb balancing stuff (not really looked into this yet).

There are plenty of shops in the states that sell cool bits for old bikes, have purchased stuff from 4 into 1 and Dime city in the past. Was hunting everywhere for the speedo and tacho that i wanted, a few crop up on ebay but they are always £30+ postage and you'll probably be stung with import duties etc.

Found this cool website https://modernmotorcyclecompany.eu who sold exactly what i was looking for, decent price cheap postage etc. Might be of use to some of you?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 05, 2018, 03:36:54 PM
Decided to pour 5L of white vinegar into the tank and leave for a few days. Didn't want to use my rebuild petcock with new seals as i don't think the vinegar will do them any good so i used an old one with perished seals that i had to fill full of vaseline.

(https://s33.postimg.cc/wl9i54m8v/IMG_1720.jpg)

Tank looks a bit of a state inside but i think its mostly varnish. After a day or 2 im going to give it a good shake with some nuts and bolts, drain/strain and go again.

(https://s33.postimg.cc/q7kf1umhr/IMG_1715.jpg)
(https://s33.postimg.cc/osiud58jz/IMG_1719.jpg)

If i don't make much progress I can step it up a bit by using thinners (although a little worried it will eat the paint if i spill any and i want to keep the aged look to the tank. If that doesn't work then I've spoken to a local rad shop who will clear it out without damaging the paint. They reckon £50-100 depending on condition (rust id imagine).
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on June 05, 2018, 06:31:30 PM
That is one bad tank, you will have to used Electrolysis to get that anywhere near clean. Or take it to a pro chemical strippers.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 05, 2018, 07:55:57 PM
That is one bad tank, you will have to used Electrolysis to get that anywhere near clean. Or take it to a pro chemical strippers.

I had a crack at electrolysis ages ago, whilst a little bit bubbled up i think that the layer of varnish stopped it working properly which is why im trying to chemically attack the varnish this time round. If i don't make any headway after a few DIY attempts ill take it to a pro
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on June 06, 2018, 06:40:03 AM
Good thread!  Be interesting to see it all coming together... 8)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 06, 2018, 01:46:43 PM
No real progress with the tank after 24 hours. Its removed exposed rust as the filler cap hole just wiped clean

(https://s33.postimg.cc/k6xaicbfz/IMG_1722.jpg)

I drained the vinegar out but it was still clear

(https://s33.postimg.cc/osteqr24v/IMG_1723.jpg)

Decided to throw in some nuts and bolts with a litre or so of vinegar and shake for 10 mins resulting in some varnish chunks being knocked loose. Drained again.

(https://s33.postimg.cc/6d8xtd3fz/IMG_1725.jpg)

Refilled and will leave it another 48 hours before trying another method.

This is what was knocked out by nuts and bolts

(https://s33.postimg.cc/osteqscfj/IMG_1729.jpg)

(https://s33.postimg.cc/7fj4bvz3z/IMG_1726.jpg)

and where the chunks have come away from inside the tank it looks like clean metal which is kind of encouraging, although i feel rust is easier to deal with than old fuel varnish

(https://s33.postimg.cc/zfn7w5n4v/IMG_1728.jpg)

The powder coater had concerns of the contrast between the gloss and satin black i had chosen so i popped round so he could show me some samples. Decided to go for gloss and matt as the matt he uses isnt as flat as i thought it would be. The bits are ready to be coated now.

(https://s33.postimg.cc/60hjn6svz/IMG_1731.jpg)
(https://s33.postimg.cc/v6ihu11vz/IMG_1732.jpg)

Postman came again this morning and dropped off my Chinese special ultrasonic cleaner which im going to use on the carbs. Smaller than i thought (2l) but will fit a striped down carb in one at a time which is all i need really.

(https://s33.postimg.cc/trgx5adnj/IMG_1730.jpg)

Have applied for a dating letter from VJMCC. As i don't need to MOT this bike i can apply for the UK registration as soon as my 55/5 form gets here from the DVLA, even with the bike still in bits.
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on June 06, 2018, 04:52:18 PM
Let us know how you get on with the dvla
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 08, 2018, 09:41:04 PM
Just got back from a few days away and the old fuel varnish situation hasn’t changed. I left a piece in a capful of thinners too as an experiment but it was still very much in one solid piece with the thinners all evaporated... the powdercoater suggested steaming it out but might need to take it to the radiator shop. Interesting side note - the zinc coated bits and bolts i threw in there s few days ago to shake around for 10 minutes I wiped off with shop towel and left on the side. The vinegar completely removed the zinc coating on them!

Unfortunately whilst all the hits have been painted I wasn’t able to pick them up today, was hoping to have the engine in the frame at least tonight but no cigar.

I have however completed all my paperwork for the DVLA, wasn’t as difficult as first thought as half of t is irrelevant anyway.

Plan is to get the engine in the frame with headstock and swing arm on at a minimum tomorrow depending on how much free time I have. I brought the engine home today, forgot how difficult it is to get in and out of a saloon boot single handed  ;D
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on June 08, 2018, 11:15:55 PM
You could try acetone (carb or brake cleaner) to dissolve the varnish sample.

Or from a plumber's supply,  the thinners they use on polypipe to clean it or thin the adhesive to see if either will have an impact.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 08, 2018, 11:27:53 PM
You could try acetone (carb or brake cleaner) to dissolve the varnish sample.

Or from a plumber's supply,  the thinners they use on polypipe to clean it or thin the adhesive to see if either will have an impact.

i left a chunk of the varnish in brake cleaner for 24hrs and again, had no effect. I suppose if could take longer than that but it didn't even soften
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on June 08, 2018, 11:38:59 PM
The polypipe thinners is different altogether so may be worth checking.

Used to use it alot but can't remember right now what chemical solvent it is.  Definitely not acetone though so could give a result.
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on June 09, 2018, 08:34:09 AM
If you look on the US site they seem to like Muratic acid---whatever that is
Title: Re: CB750 Barn find project - First Timer
Post by: SteveD CB500K0 on June 09, 2018, 08:46:05 AM
Where’s Ash when we need him?


Sent from my iPhone using Tapatalk
Title: Re: CB750 Barn find project - First Timer
Post by: Seabeowner on June 09, 2018, 09:00:08 AM
Where’s Ash when we need him?


Sent from my iPhone using Tapatalk
It's a shame he's not active, certainly missing him. Hope he's fine.
Title: Re: CB750 Barn find project - First Timer
Post by: sye on June 09, 2018, 10:49:35 AM
It would seem that Muriatic Acid is hydrochloric acid over here and it's most common use is as a brick cleaner:
https://www.toolstation.com/shop/p29118?r=googleshopping&rr=marin&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&gclid=EAIaIQobChMIg6vyl6bG2wIVaLXtCh0FlwSnEAQYASABEgJjEPD_BwE

It can also be obtained rather cheaply from chemical suppliers:
http://darrantchemicals.co.uk/muriatic-acid

Title: Re: CB750 Barn find project - First Timer
Post by: 71 V12 on June 09, 2018, 11:00:11 AM
I don’t know where you are in the U.K. but this company cleaned my tank recently. I would say it was worse than yours. Like brand new inside now. They charge about £40 and turn around in 48hours.

Voith Industial Services
Warwick House, Watling Street
Wilnecote
Tamworth Staffordshire B77 5BH
United Kingdom

Just off the M42 jnc 9.

Cheers

Kevin
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 09, 2018, 03:02:20 PM
Engine back in, but turns out we’ve got a bit of a houseful today so not got much further.


(https://s33.postimg.cc/69ocruua7/0_A1_C6_DFF-17_D2-4274-_B2_F7-51939276_C2_B1.jpg)


Seems the powder coater missed taping the thread for the grease nipple on the swing arm. Tried cleaning it out best as I can and screwing it in but I think the grease nipple has started to cross thread

(https://s33.postimg.cc/3tmjehwxb/IMG_1742.jpg)

What size thread is it? 6mmx1mm pitch? I’ve got a tap I can run down it but wanted to check first as I don’t want to wreck the thread in the swingarm if I can avoid it - is this a known weak spot?
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on June 09, 2018, 05:47:54 PM
Not normaly weak, that has to be a later swing arm if it only has one nipple underneath
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 09, 2018, 06:22:13 PM
Not normaly weak, that has to be a later swing arm if it only has one nipple underneath

Yeah it is, basically what’s the best way to get paint out the thread?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 09, 2018, 09:50:10 PM
Well.. I ended up getting the grease nipple threaded in, huzzah! Can get the rear end all bolted up...
Maybe not. After I installed the swingarm I was moving the swingarm down to get the shocks bolted up and I managed to snap the grease nipple off against the engine casing somehow..


(https://s33.postimg.cc/no4g61tcf/6008_FDC5-108_C-4_D4_E-_B19_A-_C171_B7_F4619_E.jpg)

(https://s33.postimg.cc/no4g61tcf/6008_FDC5-108_C-4_D4_E-_B19_A-_C171_B7_F4619_E.jpg)

Really annoying. Might be because i had the grease nipple pointing forward towards he front of the bike, must be a really tight clearance thought.

On another not in having an issue getting my front wheel bearing retainer in, it’s a pattern part and it seems the threads are ‘tighter’ than the oem one I’ve got (which is mangled) a anyone else noticed this?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 10, 2018, 09:57:40 AM
Rear wheel laced up
(https://s33.postimg.cc/dwbvup08f/C4_D1_E171-_AEF9-49_D6-97_AF-97_F8508474_EC.jpg)

And this is as far as I can get the front bearing retainer in, even tried hitting it with the impact driver  ::)

(https://s33.postimg.cc/wbwcs4onj/7_E57_F1_E1-8_B74-434_C-_ABE2-6036_A5_F2_AEED.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: MCTID on June 10, 2018, 11:32:40 AM
Mine was just the same......it was an absolute pig to get it out.....you should have seen the 'Heath Robinson' affair I rigged up on my Workmate to remove the rear Bearing Retainer (I'd stripped the rim off it - so it was just the hub).

I bought new Bearing Retainers but they also proved tight to insert so I asked my local Machine Shop to 'ease' out the threads in the Hubs......which worked a treat......well worth £20 for both Hubs.

The way I looked at it was that I wouldn't like the next person who stripped a Bearing out to go through what I had to.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 10, 2018, 11:54:56 AM
Mine was just the same......it was an absolute pig to get it out.....you should have seen the 'Heath Robinson' affair I rigged up on my Workmate to remove the rear Bearing Retainer (I'd stripped the rim off it - so it was just the hub).

I bought new Bearing Retainers but they also proved tight to insert so I asked my local Machine Shop to 'ease' out the threads in the Hubs......which worked a treat......well worth £20 for both Hubs.

The way I looked at it was that I wouldn't like the next person who stripped a Bearing out to go through what I had to.

Might go down this route, was it the hub the machines the threads in or the bearing retainer? Might hold tight on lacing the front wheel up. Seems a bit of a joke to have these things staked in, on what planet are these things backing out?

Once all the bearing retainers are in I was thinking of putting a glob of locktite down each stake hole rather than restaking - any issues with this?


On a more positive note I got the snapped grease nipple out the swingarm

(https://s33.postimg.cc/sre9e3te7/0_F1980_B0-0962-42_A9-_A39_B-_F31_F5_E98_C2_EE.jpg)

The first time in history an easyout has worked
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 10, 2018, 04:22:34 PM
This is as far as I’m going to get this weekend.

(https://s33.postimg.cc/ebnm7032n/8_C287_D2_D-67_D5-4_B2_A-82_B8-_BFA845_BF9_A71.jpg)
(https://s33.postimg.cc/6vocl82in/5_BCAC643-_AC42-4_AEC-8_AAC-_B9_C9538_B2551.jpg)

Relatively happy I suppose, looking forward to getting the wheels on.

I’ve put some hagon shocks on which seem to be a really tight fit, the top of the shock is touching the frame.

(https://s33.postimg.cc/x3zhalewf/775_AA280-503_B-4426-_B615-_D1_BF3_E073_F35.jpg)
(https://s33.postimg.cc/4ecldx8bj/A1183_D75-1445-4_D06-_A32_A-6_B10_F78507_FF.jpg)
(https://s33.postimg.cc/afaab0psv/FEFEEAC3-_ACBF-417_A-93_A5-480_E7_F6_B40_F3.jpg)

These were supposed to be direct bolt on replacements
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on June 10, 2018, 04:44:40 PM
Send the buggers back! 😄

Seriously, they won’t have been cheap. I bought some for 50 quid (not hagons) and they fit perfectly....
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 10, 2018, 05:14:39 PM
Send the buggers back! 😄

Seriously, they won’t have been cheap. I bought some for 50 quid (not hagons) and they fit perfectly....

the only problem is despite them being new out the box they have been sitting in my garage for 18 months!I bought them though ebay as well and they were about 35% cheaper..

Ive emailed Hagon anyway as it may be that they can provide a thicker collar thing that would push the whole assembly down slightly. If not ill have to make up some spacers so it won't be disastrous
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on June 11, 2018, 11:23:58 AM
With the bearing retainers,  are you using a grease or lubricant to install them?

Going back a bit to the tank,  the solvent I've remembered now is MEK which may get the coating to dissolve. It's used quite a bit in industry for cleaning and working with polymers in various compositions. Should be readily available.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 11, 2018, 02:07:09 PM
With the bearing retainers,  are you using a grease or lubricant to install them?

Going back a bit to the tank,  the solvent I've remembered now is MEK which may get the coating to dissolve. It's used quite a bit in industry for cleaning and working with polymers in various compositions. Should be readily available.

Yeah I used a bit of lithium grease on them
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 11, 2018, 05:17:04 PM
Mine was just the same......it was an absolute pig to get it out.....you should have seen the 'Heath Robinson' affair I rigged up on my Workmate to remove the rear Bearing Retainer (I'd stripped the rim off it - so it was just the hub).

I bought new Bearing Retainers but they also proved tight to insert so I asked my local Machine Shop to 'ease' out the threads in the Hubs......which worked a treat......well worth £20 for both Hubs.

The way I looked at it was that I wouldn't like the next person who stripped a Bearing out to go through what I had to.

Just went to two machine shops, first place said they didn’t have the tooling to do it and the second wouldn’t turn a machine on for less than £50! Going To buy an oem one to see if it’s a better fit
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 11, 2018, 05:34:09 PM
Just checked and the retainer I can’t get in IS oem  :-\
I think l might try getting it in the freezer and heating the hub up with a hair dryer

Buuut on a positive note hagon are sending me the correct spring retainers for free even though I didn’t buy direct from them!
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 12, 2018, 06:28:07 PM
Got a thread file on its way to try and sort this hub, retainer issue.

I need to wire up the new fuse box I’ve got to order some spade connectors,
What size spade terminals are used in the block connectors? I reckon it’s 4.8mm but I’m not at home this week to measure up
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 16, 2018, 01:52:11 PM
Got the new retainers from hagon this morning so that’s the shocks sorted
(https://s22.postimg.cc/aroa7fuxt/9_FC3475_A-684_F-4_B0_C-8_AF1-9_E8_C5_E5644_BD.jpg)

Also my thread file arrived so spend 10 mins chasing out the thread on the front hip and bearing retainer..

Et voila!

(https://s22.postimg.cc/5g9dmrj5t/B5575681-_C6_CB-4_F12-932_E-6_A6284_BB5029.jpg)

Well worth the investment of a few pound!
(https://s22.postimg.cc/8n3x6dvw1/0_F7_F7241-_CF0_B-4491-8_D8_E-_FFACAE5023_D5.jpg)
 Can do both internal and external threads

Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 17, 2018, 02:07:25 PM
Doing my carbs today in the US cleaner. Managed to round out one of the little screws in the carb slide,rats.

(https://s33.postimg.cc/704rvjdhr/E6_D1_A3_B0-8158-46_D7-_A3_F6-_B72_C669_A5_A09.jpg)

Easy out didn’t work, is just mullering the head even more.

Tried a very small drill from underneath but had no luck, decided to stop and have a think as the internal threads will be very delicate

(https://s33.postimg.cc/pefb02v3j/D9_D6_DA1_E-_FEC3-42_DB-_BC9_B-7_D2_EA554_E250.jpg)

Suggestions appreciated!
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on June 17, 2018, 07:28:13 PM
Small drill down the centre and a stud remover but will be tricky.... Or a more expensive but reliable method, take it to a wire eroding specialist.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 17, 2018, 08:34:44 PM
Small drill down the centre and a stud remover but will be tricky.... Or a more expensive but reliable method, take it to a wire eroding specialist.

Bit more persistence and I got it out with an easyout. Someone’s been in these carbs before as the two little screws which hold the needle in are mismatched on a few of the carbs with some of them being chewed up. My parts fiche has these down as m3x10 but they seem to be 2.5mm in dia. Will see what B&Q stock and possible replace them all with zinc coated slotted heads machine screws.

I read somewhere about these being loctited or even Peened in..? Sort of makes sense but when I’m rebuilding is it safe to leave as is because I’m going to be adjusting needle positions etc
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 18, 2018, 12:58:12 PM
Got some new machine screws for the carbs, going to replace hem all with hex heads as no doubt I’ll be changing needle heights in the future a fair bit.

So last week I called the nearest radiator shop otoday me (hourish away) to ask what could be done about the fuel tank crud and he told me to bring It in. Drove all the way down only to be told he couldn’t do anything. Not quite sure what he was expecting to see as I explained in detail the situation, he took a quick look in with his torch and said three no access to clear the crap at the bottom out (obviously as it’s a fuel tank!). Said he had no solvents he could use as all the caustic soda stuff is outlawed. He suggested maybe blasting it.

Has anyone ever heard of the inside of tanks getting soda blasted? Obviously access would dictate only certain areas could be got at but I feel this is the last chance saloon for this tank. If I have no luck here I’ll have to look at getting another
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on June 18, 2018, 04:34:43 PM
If it is that bad cut the bottom out of the tank, clean it out and get a rad shop to weld the bottom back in, used to be done a lot to do tank repairs for insurance companies
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 19, 2018, 03:45:29 PM
If it is that bad cut the bottom out of the tank, clean it out and get a rad shop to weld the bottom back in, used to be done a lot to do tank repairs for insurance companies

Yeah think that’s got to be the next step, don’t particularly want to use the bloke at the rad shop I went to as he wasn’t very helpful. Super thin guage is outside my welding capabilities and should probably be tigged anyway so going  I have an ask about locally
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 19, 2018, 06:30:19 PM
Got my other fork lower back that got recoated so managed to bolt the front end up today. I’ve been soaking all my rubber bits in wintersgreen, has worked perfectly in the carb boots but the gators which were so hard I couldn’t get them on have now gone a bit too soft. Anyone know of any methods to shrink rubber? It’s saggy where it seals round the top.

(https://s22.postimg.cc/j3rw1lk75/FC49_C2_EE-_CC59-44_D2-8426-82_FB23_CA5_CE8.jpg)

Other than that I’m happy with how the front end is looking

(https://s22.postimg.cc/mamfl7wxd/3_A703744-_AA4_A-4_A10-_A7_CD-7_FB6_D0152_DC0.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 22, 2018, 07:47:34 PM
Been working on the electrics today, think I’ve got everything sorted bar the switchgear stuff. Wheels are currently getting trued and feel like I need to be sat on the bike to drill the holes for the cables (I’m going to wire the controls inside the bars).

Think I’ve got the basic routing sorted
(https://s22.postimg.cc/5ud3mf7jl/915_B9607-868_F-4_F4_C-8_DAE-5_F294_D5_E9582.jpg)

Here’s the battery box with the blade fuse box I knocked up
(https://s22.postimg.cc/y78lcvlk1/287_B3_B20-_A164-46_A3-_A7_DB-_E5960_ACF693_A.jpg)

I’ve done the starter safety bypass on the loom with a jumper cable, but I’ll probably remove the block connector and come up with a neater solution when it’s tested

(https://s22.postimg.cc/cktkvtkep/3_A816836-_B4_B8-41_A3-985_F-3404_CE5_B363_C.jpg)m

Can someone confirm the correct routing for the cables from the alternator? Seem to remember this is how it was when I stripped it down but it’s going to be dangerously close to the chain. Perhaps that wire retainer tab is on the wrong crank case bolt?
(https://s22.postimg.cc/uav9gwg01/4_E24_F4_B6-_C0_C7-4_F26-_BAAC-_EEE5_E06_CC210.jpg)

Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 24, 2018, 09:44:09 AM
Carbs rebuilt and back on. Revived the carb boots so they are now nice and soft so easy to get on and off (which I think I’m going to be doing a lot of to get them dialled in!).

Just need the wheels back now so I can drill the bars for the front end electrics and then brakes and drive train. Few other bits but I don’t think it will be too much longer now

(https://s22.postimg.cc/t3wxz77pt/8056_AF20-046_C-4731-8_D6_A-_D0_EB6602_FBC4.jpg)

(https://s22.postimg.cc/j6lx65fjl/BC9_E0_C4_B-13_AA-4772-84_CA-_D2_BD4_CBBE4_AB.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 28, 2018, 09:21:54 AM
Called the bloke who is trying my wheels and fitting tyres, still hasn’t done it and he thinks he won’t have it done until next weekend. So that will be almost 3 weeks..
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on June 28, 2018, 09:29:00 AM
It's coming along,  nice when you get it on to it's wheels as it feels more like a bike then.

Two posts back,  did you resolve the cable routing near the sprocket? They should all go along that top edge up away from the sprocket,  there's a small capture ledge inside the sprocket cover which would ordinarily keep them out of the way.  The cables all come out of a gap at the top right hand corner in that photo.  You'll see if you look at the cover casting.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 28, 2018, 10:01:44 AM
It's coming along,  nice when you get it on to it's wheels as it feels more like a bike then.

Two posts back,  did you resolve the cable routing near the sprocket? They should all go along that top edge up away from the sprocket,  there's a small capture ledge inside the sprocket cover which would ordinarily keep them out of the way.  The cables all come out of a gap at the top right hand corner in that photo.  You'll see if you look at the cover casting.

Haven’t put the sprocket cover back on yet, just confused why the bendy cable tidy attached to one of the crank case bolts seems to be in the wrong place, but I have a picture of it’s location from when I stripped the bike down so it’s definitely gone back where it was
Title: Re: CB750 Barn find project - First Timer
Post by: hairygit on June 28, 2018, 12:47:22 PM
Just because it was in that location when you stripped it, does not mean it's the correct place. 40+ years of previous owners, any one of them could have fitted it incorrectly!
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 28, 2018, 01:27:53 PM
Just because it was in that location when you stripped it, does not mean it's the correct place. 40+ years of previous owners, any one of them could have fitted it incorrectly!

Yeah fair one, you able to confirm if that tab is on the right bolt (picture a few pics up)?
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on June 28, 2018, 02:38:05 PM
The loom tab goes on the bolt to the left, tab facing up and the loom and the starter lead run along the top of the cases and exit via the sprocket cover  ;)
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on June 28, 2018, 02:41:12 PM
I've a picture in Honda's own workshop manual that shows that bolt which you have a clip on as clear of any fittings.

It also shows all the cables routed up along that top ledge just under the engine number.

I'm familiar with putting that cover on as you can juuuuuuust wiggle it in there without having to move anything out of the way. You slide it in there with the cables located inside the cover and it finally drops into place at bottom left corner when it seems like the frame seem is going to prevent it.

What I can't remember is if it has that cable tidy fixed to the top crankcase bolt is there, it's not clear in the photo, but have vague memories of it on that bolt and bent upwards to wrap round the cables above the bolt head.
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on June 28, 2018, 02:43:04 PM
Crossed over with Trigger there as I was typing reply as her answered.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 30, 2018, 03:06:36 PM
Had a problem with my tyres, was sent the wrong front tyre (for the second time!) but it had an incorrect sticker on it which stated the correct size but the tyre was different. Unfortunate as now I have to wait for it to be replaced to get the wheels on. Had the rear back and built it up but just seen the tyre is on backwards so have to get that changed too!

(https://s8.postimg.cc/bevvbpbbp/16_A6_E739-3_E21-461_F-_A66_E-07_C008_D8_E4_DA.jpg)

Going to look good though.

Had a second rejection letter from the DVLA stating they needed a written letter stating why I didn’t have the import cert (which I had sent them) gave them a call and it turns out they also need proof of purchase.

Annoying as instead of just emailing or calling you they wait 2 weeks then send the entire document pack along with the payment back to you and then take another two weeks to get back to you once you’ve returned it  >:(
Title: Re: CB750 Barn find project - First Timer
Post by: Green1 on June 30, 2018, 04:27:58 PM
There looking smart so will be worth it in the end.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on June 30, 2018, 09:43:49 PM
There looking smart so will be worth it in the end.

Cheers mate, would have rather blacks spokes but they were more hassle than they were worth. Should I be restaking the rear wheel bearing retainer and hub bearing retainer? Nothing mentioned in hondamans book about it
Title: Re: CB750 Barn find project - First Timer
Post by: Green1 on June 30, 2018, 10:17:48 PM
I did re-stake mine Just gave it a sharp belt with a punch.
The spokes soon go black if you don't clean them.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 01, 2018, 06:49:24 PM
I did re-stake mine Just gave it a sharp belt with a punch.
The spokes soon go black if you don't clean them.

might as well just in case then if its that easy.

Im still yet to put oil in my forks as I've not got the front wheel back yet but will be doing it this week sometime. I've got Hagon progressive fork springs and im unsure about how much to put it.

On the website it state 160mm air gap:

https://www.hagon-shocks.co.uk/catalog/partdetail.aspx?partno=400-083-02

the instructions that came with the forks don't mention any air gap and are incredibly vague. is it a case of just filling the forks up to 160mm from the top of the tubes and thats it? presumably thats with springs in. If anyones got any experience fitting these then please pipe up!

The shop manual for the standard springs suggests 145CC of ATF oil in each fork. Would be easier if Hagon specified a volume rather than gap
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on July 01, 2018, 07:28:37 PM
Think the 160mm air gap would be more accurate a measure if you were to drain and then refill the forks as it would accommodate any residual oil left inside the assembly and not cause you to increase the volume.

It's not too critical as 145ml should be fine to make sure all the damper functions are covered and operated as expected.

You'd trim the 160mm measurement if you wanted to get the air gap adding to the spring rate (it effectively makes an air spring if the fork seals hold the pressure) as the fork reached full compression.  To be honest, it's not something most people would notice in general use.
If the fork stoke is 102mm,  you've got to allow at least that before the oil hits the top of the fork cap and stops it compressing hydraulically.
So in reality,  allowing for some space above the oil,  you've only probably between 130 to 160  to play with total.

If they are totally dry then 145ml is accurate enough.  If not certain, then with springs installed the 160mm is probably most concise.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 01, 2018, 08:01:46 PM
Think the 160mm air gap would be more accurate a measure if you were to drain and then refill the forks as it would accommodate any residual oil left inside the assembly and not cause you to increase the volume.

It's not too critical as 145ml should be fine to make sure all the damper functions are covered and operated as expected.

You'd trim the 160mm measurement if you wanted to get the air gap adding to the spring rate (it effectively makes an air spring if the fork seals hold the pressure) as the fork reached full compression.  To be honest, it's not something most people would notice in general use.
If the fork stoke is 102mm,  you've got to allow at least that before the oil hits the top of the fork cap and stops it compressing hydraulically.
So in reality,  allowing for some space above the oil,  you've only probably between 130 to 160  to play with total.

If they are totally dry then 145ml is accurate enough.  If not certain, then with springs installed the 160mm is probably most concise.

Forks are bone dry so might just pour in 145ml and see where that gets me, thanks for shedding some light on this.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 06, 2018, 07:06:21 PM
Done a few things this week, a friend sandblasted the inside of the tank with mediocre results so I’ve cut the two flat sections on the bottom out for better access, will see what that yields! Managed to get some huge chunks of resin out though.

Wheels are back and quickly stuck the rear on when I finished work, can’t seen to get the rear brake mechanism in place as it’s hitting the swingarm. Very close though so might just be that the bike needs to be on the ground to move the swingarm up to allow the linkage into place.

Also had a small amount of rust in the oil tank, soaked in vinegar all week which cleaned it up nicely, then neutralised with bicarbonate of soda. Unfortunately I got a bit of flash rust so may just use bottle brushes and carb cleaner and see how I get on
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on July 06, 2018, 07:16:01 PM
The rear brake mechanism goes to the front of the swinging arm (between the arm and engine). It needs to be put on (through the frame mount) before you put the swinging arm on  ;)


This goes on before the arm

[attachimg=1]
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 06, 2018, 08:32:21 PM
The rear brake mechanism goes to the front of the swinging arm (between the arm and engine). It needs to be put on (through the frame mount) before you put the swinging arm on  ;)


This goes on before the arm

(Attachment Link)
Well that’s a pain!
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on July 06, 2018, 08:38:15 PM
Also attach the brake rod to it, not easy to get the pin in and the split pin afterwards  ;)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 08, 2018, 07:35:42 AM
Also attach the brake rod to it, not easy to get the pin in and the split pin afterwards  ;)
All sorted now. Spent ages trying to crack it with the swingarm still on but it’s impossible to get the spring into place so had to strip the rear end back down like you said. Made some good progress, both wheels on, both brakes on, bars internally wired and installed. Hopefully can crack the electrics today.

One thing I’ve noticed is there’s a reaaaally tight clearance between the swing arm grease nipple and the little bracket for the carb bowl overflow tubes at the back of the engine

(https://s33.postimg.cc/hehv9l6r3/D7155363-7_D0_C-441_F-_BB8_C-9_F745_B567699.jpg)

Ive purposely bent the bracket to allow enough clearance there, it’s not the original grease nipple as that one snapped a while ago when it hit that bracket when installing the swing arm for the first time! Have I missed something here?
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on July 08, 2018, 04:52:19 PM
Also attach the brake rod to it, not easy to get the pin in and the split pin afterwards  ;)

I found this out the hard way.....although not impossible it is a pain in the arse.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 08, 2018, 04:55:17 PM
Had some slow progress today with the wiring. Basically all I’ve managed to achieve is an oil pressure light and a gurgle from the horn. Tried the horn directly onto the battery and it’s plently load which makes me think it’s a ground issue. The frame ground is bare metal as I’d already sanded it back. I haven’t sanded the frame on the engine ground as I didn’t think it was needed. Seeing that the switches ground through the handlebars should I be removing paint for this? Only one of them (left) has that drilled locating tab.

(https://s15.postimg.cc/kp3aqg2l7/7583_A8_CC-964_C-4_FDE-82_DF-_AD97_E4464917.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on July 08, 2018, 07:35:35 PM
The horn needs to go to ground , the earth lead and the coils  ;) If you have drilled the bars, be careful that they don't snap :o
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 08, 2018, 08:00:45 PM
The horn needs to go to ground , the earth lead and the coils  ;) If you have drilled the bars, be careful that they don't snap :o

I think the ground for the horn is in the actual switchgear itself and grounds to the bars? Would make sense as the horn could be weak from having to ground through a layer of powder coat.

They are steel bars so should be good to go with a few little holes
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on July 08, 2018, 08:10:30 PM
Nope, the ground to the horn is PN 38105 323 000  ;) Or 38120 392 620
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 08, 2018, 08:38:52 PM
Nope, the ground to the horn is PN 38105 323 000  ;) Or 38120 392 620

Yeah I’ve got that, just connects the horn to the harness by the coils, so all good there. Next step is to get some batteries in my multimeter and start poking around. Wish I’d just spend the extra few ££ and got a K6 harness rather than shoehorning an earlier one in
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 09, 2018, 10:08:28 PM
I think I’m going to repair the old harness and try that, conditions not too bad, couple of connectors need cleaning up and the connection to the battery +ve is a little fried.

What else can I do outside of a spray with contact cleaner to try and improve the state of all the bullet connectors?
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on July 09, 2018, 10:24:51 PM
Change any bullet and spades. If you see any green on the wires, then cut back. Corrosion is not your friend on these old girls  ;)

I found a little corrosion on a regulator the other week that cooked a brand new battery  >:(
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 09, 2018, 10:36:44 PM
Change any bullet and spades. If you see any green on the wires, then cut back. Corrosion is not your friend on these old girls  ;)

I found a little corrosion on a regulator the other week that cooked a brand new battery  >:(

Ok might as well go all in then. I had to stick a punch of bullet connectors on a universal speedo gauge, I thought Honda used 3.5mm connectors so bought some on eBay and they seem a little small, the female connectors are fine but the males struggle to stay in. I’m guessing I should be using 3.9mm?

Any recommended sources or are they all much of a muchness?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 13, 2018, 02:40:19 PM
Nope, the ground to the horn is PN 38105 323 000  ;) Or 38120 392 620

Mate just had another look at the wiring diagram and it seems the horn button does ground on the bars

http://manuals.sohc4.net/cb750k/technical_reference/WD750K6.pdf

Surely this would require a good ground to the bars and a good ground from the bars to the upper fork clamps. Might have to sand a little bit of powder coat off.

Some positive news today, my V5 finally arrived after many headaches. DVLA were particularly useless.

I’m side mounding the plate so going to have it in 3 lines, what’s the correct format for this? I’ve seen:

  X
XXX
XXX

 XX
 XX
XXX

And

XXX
XXX
  X



Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on July 13, 2018, 03:35:58 PM
All need a good ground or you will have trouble  ;)
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on July 13, 2018, 03:42:05 PM
[attachimg=1]

Can be white or silver on black if pre 1977 (rolling)
But, you can have it on 3 lines if registered prior to 2001.
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on July 13, 2018, 08:06:52 PM
Part of the grounding system is the headlamp shell bolts that screw into fixed nuts with ground wires that connect to loom
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 14, 2018, 03:31:15 PM
absolutely sick of the electrics on this bike. Unwrapped the old harness and replaced any bits of wire that looked dodgy, replaced a lot of connections and cleaned the rest up. Re-wrapped it and fitted to the bike. All I've got is a bloody oil pressure light still!

Feel like sacking it for a few weeks as I've totally stopped enjoying working on it.
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on July 14, 2018, 04:13:58 PM
The fun of custom builds, that is why i hate them.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 14, 2018, 04:42:09 PM
The fun of custom builds, that is why i hate them.

I’ve really enjoyed the physical modifying of the bike, the cutting and welding etc but I’m finding it hard to stay motivated with the electrics as it’s something that really doesn’t float my boat.

I’m considering buying a new K6 harness. I bought an earlier harness but it’s proving a pain to get it to work without a starter safety unit.

Although it’s a custom build the electrics are basically unchanged, the idiot lights are integrated into the speedo but the standard wiring should work. The only real difference is the left hand switchgear has a hi low switch. The old harness had a jumper cable (presumably as standard) to allow for the lack of on off headlight switch on the K6.. I can’t remember where it went though!
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on July 14, 2018, 05:22:30 PM
I seem to remember brown/red went from rh switch to fusebox and returned to headlamp as a brown/blue
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 14, 2018, 06:59:17 PM
I seem to remember brown/red went from rh switch to fusebox and returned to headlamp as a brown/blue

When I unwrapped the original harness some of the colours actually change inside the wrap, i think it was black/red coming from the bucket and changing mid harness into brown red to go into the fuse box. Strange

There’s a bloke on eBay selling k6 harnesses from Germany (but says made in Japan) for £95, DS does them the same sort of price. Anyone got any experience with either of these?
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on July 14, 2018, 09:52:14 PM
If you are building a special might as well make up your own loom mate
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 14, 2018, 10:12:47 PM
If you are building a special might as well make up your own loom mate

It’s not really a special in terms of electrics, the only addition is a repro right hand switch that gives me headlight on/off (which it didn’t originally have).

I think making a harness myself is beyond my skill set and something I’m not motivated enough to learn how to do so I’d have to farm it out to someone else which would no doubt cost many times what a repro harness costs
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on July 14, 2018, 10:23:06 PM
Where in the south west are you? anywhere ne Gloucester
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 14, 2018, 10:45:40 PM
Where in the south west are you? anywhere ne Gloucester

I’m near taunton, not a million miles away
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on July 15, 2018, 01:17:34 AM
Take me about 5 hours to build you a loom as long as all the bits are to hand, if you can get it here. My pickup only does 20 mpg so would be pricy to come down
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on July 15, 2018, 09:29:43 AM
Nope, the ground to the horn is PN 38105 323 000  ;) Or 38120 392 620


Some positive news today, my V5 finally arrived after many headaches. DVLA were particularly useless.



Hi UD, i see you managed to register the us import, without first obtaining an mot... what documents did they require
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 15, 2018, 03:20:56 PM
Nope, the ground to the horn is PN 38105 323 000  ;) Or 38120 392 620


Some positive news today, my V5 finally arrived after many headaches. DVLA were particularly useless.



Hi UD, i see you managed to register the us import, without first obtaining an mot... what documents did they require


In full for a bike that doesn’t have its original foreign registration docs the process goes:

Apply for a dating certificate through the VJMC by sending them:

Pics of frame, engine and headstock numbers
Pics of the bike from each side (bike must be in one piece)
Completed dating application letter form
Payment of £35

(This is all explained on VJMC.com)

Once you’ve received the dating letter from them you can then apply for the V5 from the DVLA:
If the bike needs an mot this is where you go get one, if it doesn’t fill it a V112 form
Complete a V55/5 form (most of this doesn’t actually need to be filled out- I just did what I could and it was enough
Proof of ID
Postal order for £55
VJMC dating letter
I included all the pictures of the bike and numbers etc that I sent to the VJMC (although not sure if I needed to)
Proof of ownership (invoice/sales order etc)
Copy of the nova approval (again just included because I had it to hand)
And finally: INCLUDE A LETTER THAT STATES YOU DO NOT HAVE THE ORIGINAL IMPORT CERTIFIATE AS IT WASN AVAILABLE AT TIME OF PURCHASE - this is basically the reason why my application got rejected twice, the instruction you get is vague at best!

There’s a half decent guide here http://www.davidsilverspares.co.uk/USED-BIKES-WARRANTY

Good luck with it and PM me of you need any more help



Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on July 15, 2018, 03:51:04 PM
Nice one UD. I already have the dating letter from vjmc, and a letter from honda saying they can’t date it.... I was thinking it still needed an mot fot its initial registration. I will send it all off and see what happens.... cheers
Title: CB750 Barn find project - First Timer
Post by: SteveD CB500K0 on July 15, 2018, 04:05:49 PM

And finally: INCLUDE A LETTER THAT STATES YOU DO NOT HAVE THE ORIGINAL IMPORT CERTIFIATE AS IT WASN AVAILABLE AT TIME OF PURCHASE - this is basically the reason why my application got rejected twice, the instruction you get is vague at best!



Very important and new requirement - mine was rejected last week because of no covering letter.
The guy I spoke to at DVLA said the “rules” had changed the previous week.


Sent from my iPhone using Tapatalk
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 15, 2018, 05:01:48 PM

And finally: INCLUDE A LETTER THAT STATES YOU DO NOT HAVE THE ORIGINAL IMPORT CERTIFIATE AS IT WASN AVAILABLE AT TIME OF PURCHASE - this is basically the reason why my application got rejected twice, the instruction you get is vague at best!



Very important and new requirement - mine was rejected last week because of no covering letter.
The guy I spoke to at DVLA said the “rules” had changed the previous week.


Sent from my iPhone using Tapatalk

And rather than actually contacting you they wait two weeks and fire the whole application back to you with no real explanation, and when you send it back they wait another two weeks to respond!

After my first rejection I wrote a covering letter stating very clearly to call or email me if they required anything else but they chinned me off a second time and sent my pack back. I called up and asked why on Earth they wouldn’t just call people to ask them to email further details and the bloke couldn’t give me an answer
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 20, 2018, 06:46:05 PM
Another weekend another question!

Been doing all the cables this evening, when doing the clutch cable the arm was in the correct place but I pushed it forward hard to get the cable in and it stayed forward. Have tried giving it a tap but it won’t disengage. Anyone got any tips? The clutch is bone dry as there’s no oil in the bike and obviously the bikes been standing a long time.

(https://s15.postimg.cc/yapwsq5ob/3_C6_FAA2_E-_AB4_F-4_E97-_B485-_FB95_D194_F177.jpg)

Please note the clutch arm is on backwards as it gave me something to tap with a rubber mallet. Little reluctant to take the cover off as I gave the gasket a good coating of hondabond
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on July 20, 2018, 09:30:34 PM
Take the clutch housing off again and you should never use sealant on a gasket, you will get strings that will block the oil jets. 
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 20, 2018, 09:57:50 PM
Take the clutch housing off again and you should never use sealant on a gasket, you will get strings that will block the oil jets.

Hondaman recommends it in his book IIRC due to it being a common site of oil leaks?
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on July 20, 2018, 10:27:02 PM
Take the clutch housing off again and you should never use sealant on a gasket, you will get strings that will block the oil jets.

Hondaman recommends it in his book IIRC due to it being a common site of oil leaks?

Well, if Hondaman recommends it, then i better start using it on gaskets after 28 years  ;D ;D ;D

Didn't the Hondaman book tell you to attach the cable to the clutch arm, before the clutch lever  ;D
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 21, 2018, 12:57:08 PM
Take the clutch housing off again and you should never use sealant on a gasket, you will get strings that will block the oil jets.

Hondaman recommends it in his book IIRC due to it being a common site of oil leaks?

Well, if Hondaman recommends it, then i better start using it on gaskets after 28 years  ;D ;D ;D

Didn't the Hondaman book tell you to attach the cable to the clutch arm, before the clutch lever  ;D

To be fair it’s been so long since I rebuilt the lump I can’t really remember the reason for some of the things I did!

Got it all sorted now, unsure how it all went out of alignment but it was easy enough to figure out once I popped the housing off.

I’ve got the throttle cables all working smoothly but where the pull cable attaches to the arm on the carb throttle linkage it’s not quite lined up. Doesn’t appear to be any adjustment left and right outside of bending stuff.. will probably be fine but just seems like it will cause wear to the cable

(https://s15.postimg.cc/u6gobwdiz/B3822_F96-695_D-4108-_A209-_ED23_F0386_A98.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on July 21, 2018, 02:54:22 PM
Glad you got the clutch sorted. It looks like you have something in the wrong place, or wrong order on your carbs. The cable should sit exactly in line and as you have mentioned, it will foul and wear through the cable very quickly if left like that.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 21, 2018, 06:36:24 PM
Glad you got the clutch sorted. It looks like you have something in the wrong place, or wrong order on your carbs. The cable should sit exactly in line and as you have mentioned, it will foul and wear through the cable very quickly if left like that.

Looking at the picture it actually looks a little bent, will have a look tomorrow.

Update on my tank. So the thick solid mass inside it was some sort of resin tank sealer, possibly a home brew job. In the low points of the tank it was the best part of an inch thick!

A friend of mine blasted the tank best he could through the filler cap but didn’t have much success so I cut the flats out either side and blasted it again with slightly better results. After this Ive put probably 3 hours manually scraping and sanding the inside of the tank

(https://s15.postimg.cc/5dyolf7vf/E3583346-_C97_B-4873-_BA4_F-_A5_F6862_CD436.jpg)

(https://s15.postimg.cc/i5curyznv/4_A3027_AE-_A85_A-4917-_AFA4-_DF4_FC34_F477_E.jpg)

(https://s15.postimg.cc/y3lki49bf/93_EDA5_D1-03_DA-47_F1-85_A6-_F333_BB85_A9_B8.jpg)

I think that’s as good as it’s going to get, wish I’d taken a picture of all the stuff that came out of it! Going to tig braise the cut outs back in and fill with phosphoric acid to convert any little bits of rust that may be hiding. If I find my carbs keep blocking up I’ll put a proper tank sealer in it like POR15
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 21, 2018, 09:07:26 PM
Turns out that throttle cable guide bracket thing is soft and can be bent by hand so it’s bent back into the proper position now
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on July 21, 2018, 09:10:25 PM
Great, another little niggle sorted. Onwards and upwards, you are making great progress.
Title: Re: CB750 Barn find project - First Timer
Post by: Green1 on July 21, 2018, 09:20:49 PM
Turns out that throttle cable guide bracket thing is soft and can be bent by hand so it’s bent back into the proper position now

Now you mention it its clear its bent in your pic.
Somehow I didn't see that before
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 21, 2018, 09:48:55 PM
Turns out that throttle cable guide bracket thing is soft and can be bent by hand so it’s bent back into the proper position now

Now you mention it its clear its bent in your pic.
Somehow I didn't see that before

Yeah I didn’t even notice when I was scratching my head about it being out of whack earlier!
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 22, 2018, 01:45:34 PM
Quick go on the seat today. Instead of using trim strips around the seatpan to stop the cover wearing throughbo glued some vinyl material. Roughly shaped the foam with a bread knife, hard to neatly cut recon foam as it turns out! Have left the foam slightly oversized for now as it’s being covered by a friend who is a pro so he can probably trim it back a bit nearer than what I can.

(https://s15.postimg.cc/jbr08q80b/EC56_EDA6-_EA18-4_CB4-_A1_F1-_B7_B98_A96_D2_E3.jpg)

(https://s15.postimg.cc/9r7dlvdjf/B49_C5823-0371-467_C-_A3_DC-_C250_C9_C50971.jpg)

(https://s15.postimg.cc/yx8bsoze3/70_B4_EDE9-3_AB0-449_D-98_B7-_A36_E7_D6916_B6.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 22, 2018, 07:53:53 PM
not wanting to get into anything serious with the bike today I’ve made up the 4 into 1 exhaust. The reverse cone is 12 inches long and was 0.7mm too small to slide over the collector (according to my micrometer!). Cut a slit in it, lubed it up with copper slip and banged it on with a rubber mallet. The bracket is just for show as it won’t be coming off again without a fight!

(https://s15.postimg.cc/ezome9rqj/F7_FD006_A-631_E-4_F33-_A064-1_D1001418_B8_B.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on July 22, 2018, 09:23:44 PM
Any baffles in there ?  :D

Looks nice, is it a good fit onto the cyl head? The headers and collector look nicely formed, what make is it, or is it made up from various pipes?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 22, 2018, 10:28:10 PM
Any baffles in there ?  :D

Looks nice, is it a good fit onto the cyl head? The headers and collector look nicely formed, what make is it, or is it made up from various pipes?

It has a stainless steel perforated core but it’s pretty open.

(https://s15.postimg.cc/yaegzvvuj/48_BF6_A6_C-1828-47_AA-_A976-_E9_C14_CE0810_D.jpg)

Headers are from MAC and end can is From Cone Engineering, both were
Picked up when I was overseas and had 20kg baggage allowance!
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 23, 2018, 10:42:10 AM
Been thinking about the breather hose that comes from the back of the cylinder head thismorning, originally it connected to the air box but now that’s gone I need another solution.

I could just route it down to the ground so anything coming out of it would go overboard - but on a well running bike should anything be coming out of it outside of vapour? You can get fancy little filters to go on the end of the breathe hose which you can attach anywhere but in my head I’m imagining it becoming sodden with oil over time and causing a mess?
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on July 23, 2018, 10:51:19 AM
There should only be vapour coming out, unless you have a problem. The 500 does just exit to atmosphere just in front of the rear wheel
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on July 25, 2018, 09:20:10 PM
There should only be vapour coming out, unless you have a problem. The 500 does just exit to atmosphere just in front of the rear wheel

Nice one bud.

Anyone know where I can get a shorter speedo cable from? I’m not using the front fender (will use a brace) so It’s now got a lot of slack where it loops backwards, ideally I’ll just run it up the inside of the fork lower instead so could do with it being 20-30cm shorter
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on July 26, 2018, 02:06:20 AM
Dont know anybody who makes custom speedo cables, used to find longer ones in the US for the chopper boys but never seen shorter. Perhaps a different Honda bike might fit?
Title: Re: CB750 Barn find project - First Timer
Post by: petermigreen on July 26, 2018, 08:15:28 AM
Think venhill will make cables to specification.


Sent from my iPhone using Tapatalk
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 06, 2018, 06:15:19 PM
Took the old girl up to see bryanj on Saturday who helped me with the wiring

(https://s33.postimg.cc/dh8pgbai7/8_AFE21_E2-7734-4294-_BDB4-_BA002_B3_A707_F.jpg)
 
He also knocked me up some braided hoses for the front end.

Today I’ve fitted the chain, plumbed in the oil tank, fitted the exhaust,  prepped the oil pump by submerging it in oil and turning it back and forth until no air bubbles come out.

Filled her up with oil and have been kicking her over with the killswitch on to try and get the oil pressure light to go out. After 60 or so kicks no luck yet.

The kickstart seems to have a limited range of movement and it’s not springing back up. Could this be due to dry internals? Hopefully it isn’t anything assembled incorrectly!

This pic shows the end of the range on the Kickstart.

(https://s33.postimg.cc/lmqregblr/E66_BBA24-7_E79-4_F7_C-_A5_BF-54_BFC8408131.jpg)

Title: Re: CB750 Barn find project - First Timer
Post by: philward on August 06, 2018, 08:28:13 PM
Try the packing the oil pump with vaseline trick that many members recommend. I used it for the first time on the CR and oil light was out in no time (with plugs out for ease on the old legs!)
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on August 06, 2018, 09:01:17 PM
If you spin the engine on the starter the oil light should go out fairly quickly. I didnt have any trouble with the oil pump on mine, i took it out and changed the gauze but didn’t strip it completely. I never primed it, just refitted, filled up with oil and kicked her over until oil appeared at the rockers...
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 06, 2018, 09:22:59 PM
Never spin a newly rebuilt engine on the button, the button pusher tends to get carried away and if the oil isn't pumping around the engine it will seize very quickly.
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on August 06, 2018, 09:37:24 PM
Don't think much of Bryan's wiring or is this the new fashion  ;D ;D ;D kick start should always return, two springs to do the job.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 06, 2018, 10:47:03 PM
I’m hoping it’s something to do with the clutch cover stopping the Kickstarter returning properly as this has been the issue for at least one bloke on the US site. Fingers crossed I haven’t assembled the kickstart spring incorrectly!

Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 07, 2018, 06:26:38 PM
Charged the battery up today and gave it a good spin up off the starter but no pressure. Had a look in the tappet covers and it’s still dry up there. Going to have to do the Vaseline trick tomorrow.

Got the front brake set up, the actual bleeding was easy, the difficult part was tightening the fittings without the hoses kinking up.

None the wiser with the kickstart. Hoping that when I’ve got oil pressure it will all get the lube it needs and magically start working
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on August 07, 2018, 08:26:31 PM
Maybe a good idea to get some engine oil in an oil can and give a good squirt through each tappet cover just to help avoid any damage until the pump starts pumping.... good luck with it UD!
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 07, 2018, 10:10:49 PM
Dropped the oil pump back out seems it was binding in a certain position and sticking tight. Took it apart and on the inner rotors the little dent marks were on opposite sides, flipped one of them round and it’s now smooth. Packed the rotors and oil ways full of Vaseline, reassembled and no cigar. Little disappointing as I was sure I had it!

As suggested above I’ve poured some oil into the tappets to avoid any damage but there’s graphogen in there so it will probably have been fine anyway.

When I packed the rotors with Vaseline I expected it to be pushing/sucking in Vaseline as I rotated the pump back and forth but it didn’t really - is this correct?
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on August 07, 2018, 10:11:20 PM
Something odd about that kickstart,  I'd be surprised if oil will make that return correctly. Looks like you'll have to get in there to see what's happened.

For oil pressure,  pull the oil filter off to see if it's present there,  it goes from the pump straight to filter first and comes out of the hole in the crankcase (not the filter bolt as that's the exit route to rest of oil system) if you put a bowl under it the oil should appear there first and you can put the filter on to continue.

Agree with Rob62,  you need to be careful how much you turn it over with no oil supply. Youucant do much about the main bearings but you can supply the cam with some oil manually via the tappet covers.

Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on August 07, 2018, 10:17:08 PM
I crossed over your posting there.

With the Vaseline,  it'll only cause a vacuum and not go through the pump generally.  You need to make sure the oil is getting from tank via oil line to pump entrance,  if so then the Vaseline will pull the oil through with the vac it causes but if you spin the pump first before oil is available then it may not work.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 07, 2018, 10:27:13 PM
I crossed over your posting there.

With the Vaseline,  it'll only cause a vacuum and not go through the pump generally.  You need to make sure the oil is getting from tank via oil line to pump entrance,  if so then the Vaseline will pull the oil through with the vac it causes but if you spin the pump first before oil is available then it may not work.

When I removed the pump just now oil poured out of the inlet oil way from the tank so it’s definitely got a supply that side. I’ll have a look if the oil filter is wet tomorrow.

Really don’t want to remove the engine again right now, to the point where I’d rather run it without a kickstart for a while before addressing it!
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on August 07, 2018, 10:49:02 PM
I would not try running it until you have addressed the kick start problem, the cog wheel on the kick start can lock and then lock the engine via the clutch.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 07, 2018, 11:12:07 PM
I would not try running it until you have addressed the kick start problem, the cog wheel on the kick start can lock and then lock the engine via the clutch.
Drat. I’ll Remove the clutch cover bits in case that’s causing something to bind tomorrow, if I have no luck.. well I guess I better gear up to get the lump out agin  :(

Last time I stripped it down to the frame and later it on its side. Are there any methods to remove the engine from a complete bike?
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on August 07, 2018, 11:44:54 PM
Before fitting any engine you have to check that the engine turns freely via the kick start and every gear can be selected under load.
There are many problems if the oil pressure is not building up on a 750. It can even be a 0' ring at the wrong size or missing.
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on August 08, 2018, 05:30:04 AM
Trigger, that was before wrapping and whilst it was relatively straightforward it was switches from two models (LH and RH different) loom from another and bike a third so just about nothing except block connectors were a plug n play, still all keeps the grey matter working!!
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on August 08, 2018, 06:14:22 AM
Trigger, that was before wrapping and whilst it was relatively straightforward it was switches from two models (LH and RH different) loom from another and bike a third so just about nothing except block connectors were a plug n play, still all keeps the grey matter working!!

Nice ! a ten minute job then mate  ;)  ;D ;D
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 08, 2018, 10:10:48 AM
Before fitting any engine you have to check that the engine turns freely via the kick start and every gear can be selected under load.
There are many problems if the oil pressure is not building up on a 750. It can even be a 0' ring at the wrong size or missing.

Well live and learn. I tested all the gears whilst turning the crankshaft but didn’t think about the kick start. Still hoping that maybe the clutch cover is interfering as it was quite a tight fit getting it over the kickstart spindle
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 08, 2018, 06:02:26 PM
Anyone got any experience pulling an engine out the side with either an engine crane or engine hoist? Can buy them second hand pretty cheap or even hire one for a day for £20.
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on August 08, 2018, 07:01:35 PM
It should come out with two people holding it, too heavy for one. Put a load of rags round the frame and remove the exhaust stubs first then carefully lift out
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 08, 2018, 07:09:00 PM
Agree with Rob, the more protection you give the frame, the better. But, too much protection, you wont have room left to lift it out. Still very difficult to do even with 2 people, if you twist or tilt the engine in the frame even by a few mm, it will get wedged and then it is a nightmare. It is a pain but in the long run, stripping the bike down and lifting frame off is easier in the long run.
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on August 08, 2018, 07:54:24 PM
In the dim and distant past we always lifted them out of the bike standing up,  it's only on here currently that I've seen the lay down method.
Quite a few done on F2 for the valve guides etc.
Usually strip anything possible off,  newspapers about five sheets thick and taped around the frame tubes to stop chipping anything,  get a box or similar to load the engine out onto and with two people you can juggle it out.  if you got a support like the box you can stop and look round it at any point to see how you've got to move it.

With exhaust stubs removed and looking from the rhs it rotates a little clockwise to get the rear of the cases to clear the frame but it's only by a few millimeter. It only just clears.

I suppose with a bit of lateral thought you may be able to use a lift.  If you got something like a 7inch roof joist and put it vertically across the back where the carbs go,  then ratchet strapped it to the engine to secure.  If you had about a couple of meters sticking out the side of the bike and got the lift closest to the engine,  you could use the sticking out bit to counterbalance the engine while you withdrew it. S'pose you could call this the Catholic method with all that withdrawal going on.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 09, 2018, 07:43:58 AM
(http://i1141.photobucket.com/albums/n599/tentb/CB750K6%20Engine/IMG_7343.jpg)

Maybe this is the solution!
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on August 09, 2018, 07:59:33 AM
Having met you and thinking back to when i was your age and working on them all the time we used to lift them out by hand and carefully!
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on August 09, 2018, 08:21:44 AM
That looks most of the way there.  If it had a sleeve going over that scaffold pole to hold the engine straps you could pull the engine along the pole to get it out rather than shuffle the bike sideways, perhaps by using a ratchet strap to move the sleeve along the main pole.

As you say Bryan,  we normally lifted them out with two of us on it.  Quite a few friends had F2s which where in and out a few times  :)

Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on August 09, 2018, 08:49:25 AM
By the time you think and worry about getting the engine out sideways, you could of popped the wheels off, dropped the forks and removed the swing arm  ;)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 09, 2018, 09:41:15 AM
By the time you think and worry about getting the engine out sideways, you could of popped the wheels off, dropped the forks and removed the swing arm  ;)
Yeah fair one, suppose trying to save time in this way might be a false economy.

With I hadn’t just fitted the new chain with roger link on. It’s a 100 link chain and the adjusters are almost all the way out so I can’t get it off the sprockets by moving the wheel forward. Maybe I can just pop the front sprocket off to get it off that way
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on August 09, 2018, 09:52:22 AM
Just pull the rear spindle out and roll the wheel forward to get the chain off the rear sprocket.

If there's no chainguard on it you can just lift the chain off and move it to the left to get the wheel out.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 10, 2018, 02:36:02 PM
Well wrestled the engine back out this morning. Used the laying in the side method originally felt strong and tried with the wheels on but it definitely wasn’t happening so had to strip a few things off but got it out. Protected the frame with rags but let’s just say the new paintwork doesn’t look so new anymore :-\

Going to split the cases this afternoon and see what’s up. Hopefully get the lump back in some point on the weekend

(https://s8.postimg.cc/8o6x9w3ol/A3_F84658-_EB4_A-4_CC0-_A06_D-_F0_A97672_C18_D.jpg)
(https://s8.postimg.cc/wt7mr98g5/9_EBDD39_A-7_BFA-4_A59-99_CE-765417006_D85.jpg)
(https://s8.postimg.cc/guyx16r3p/6_A9_C2_FA5-_BEAF-40_CC-_AFF6-753_D5_D5_A07_AF.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 10, 2018, 06:23:50 PM
Well... found the kickstart problem.

(https://s8.postimg.cc/mwk1ejnx1/4_AF10039-3_FC6-4_E44-_B3_C6-10_BC88_BA318_A.jpg)

(https://s8.postimg.cc/dorsxvjfp/9_DCF2_B4_D-2110-4061-9_D2_C-59469_CB9_F39_A.jpg)

Kickstart gear installed incorrectly. Seems to have been able to run the oil pump fine but when kickstarting it has caused this arm to hit the casing and do the above damage.

(https://s8.postimg.cc/7ewjaemgl/84_A4_CF57-_EC2_B-4_DE1-8937-776_C1_CF1148_D.jpg)

I’m not an expert (durh, that’s why this happened) so unsure of the best course of action. Does his need repairing or is it even possible to repair? The bit that’s broken off isn’t full thickness so there’s still a divot there for the spring to sit in

(https://s8.postimg.cc/hl54tw705/69147_BAB-_AEE9-41_FF-_B89_A-481_AE835034_D.jpg)

(https://s8.postimg.cc/7gb2hvyc5/9_D627574-51_F2-4244-940_E-173_B39_DDEDA1.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: philward on August 10, 2018, 06:36:01 PM
Glad you found that - not just for solving the kickstart issue but dread to think what that chunk getting stuck in the gertrin would do
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on August 10, 2018, 08:15:41 PM
Something wrong there, you should not be able to move that spring with your finger and it should be under high tension against the case  ;)

The roll pin needs to come out and it all needs to be rotated. If i get time later i will put one in to a case and show you how it should look.
Title: Re: CB750 Barn find project - First Timer
Post by: SumpMagnet on August 10, 2018, 08:27:18 PM
Anything ( well...within reason ) is repairable. That can be welded, but yoiu would want to take it to a specialist who understands what is needed and how to avoid distorting the cases.

My pop restores old Triumphs, and he has a regular welder who does wonders with smashed crankcases. Rod through the case....snapped chain torn through the gearbox....all possible. Not cheap...but in those cases, preserving an original set of crankcases is owrth the expense. Sometimes...it's not an option to replace as the parts are not readily available anywhere.

Couldn't say how important getting the metal replaced would be...but I definitely think that confirms you were right to pull the motor and find out hte cause, rather than just press on. A few marks in the frame paint are nothing compared to a ruined gearbox
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 10, 2018, 09:11:56 PM
Something wrong there, you should not be able to move that spring with your finger and it should be under high tension against the case  ;)

The roll pin needs to come out and it all needs to be rotated. If i get time later i will put one in to a case and show you how it should look.

Yeah realised that as soon as I opened her up. That roll pin is a rascal, I’ve had it out once before and probably gave it a hefty tap back into place, doesn’t want to come out this time. Spend 30 minutes applying heat and pulling on it with pliers but no luck yet. Anyone got any tips?

Discovered the downside to hondabonding gaskets. No doubt they would have been Uber leak proof but they’ve obviously all been ruined now. Anyone got a spare clutch and gearbox gasket they don’t need  ;D
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 10, 2018, 09:19:59 PM
Trig says drill it or put a tap down it and try and pull it out.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 10, 2018, 09:27:40 PM
Trig says drill it or put a tap down it and try and pull it out.

Did consider drilling it but wasn’t sure if there was anything else to try first. Is the roll pin likely to be reusable after it’s been drilled?
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 10, 2018, 09:30:17 PM
No, there won't be much left of it. They are not available OEM anymore but I know Trig has a big trade pack of them in the engine building workshop.
Title: Re: CB750 Barn find project - First Timer
Post by: hairygit on August 10, 2018, 09:31:37 PM
Why put ANY gasket sealer anywhere other than the top to bottom crankcase joint? a smear of grease on the gasket, then if it needs to come apart again it wont trash the gasket, Honda recommend fitting them with NO sealant.
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 10, 2018, 09:35:21 PM
I bet Hondaman was responsible for the gaskets being flubbered, I think he says use gasket sealer.........😭😭😭
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 10, 2018, 09:44:32 PM
I bet Hondaman was responsible for the gaskets being flubbered, I think he says use gasket sealer.........😭😭😭
Exactly that!
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on August 10, 2018, 09:45:05 PM
Bit of bad luck there Ud.... hopefully you can get it repaired. I have a mate who is a wizard at aluminium weld repairs but he is in Hull  :( ... But those type of repairs are def possible. Try to seek out somebody who specialises in that type of thing.. Good luck !
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on August 10, 2018, 09:49:53 PM
I would be welding that damage. Once the spring is under the correct tension it may break the rest of the case.
While the engine is out i would be investigating why the oil is not getting to the top end. It only takes a little sliver of Honda bond to block the oil ways and the jets. Check that you have all the correct 0'rings in place, as one missing or wrong size 0'ring will effect the oil pressure  ;)
Title: Re: CB750 Barn find project - First Timer
Post by: Green1 on August 10, 2018, 09:52:43 PM
Never understood using sealant on gaskets. Why use a gasket if your going to use sealant?  ???
I always grease them even though it feels wrong its so right.   
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 10, 2018, 09:53:07 PM
Almost every Honda engine we get sent from USA for overhaul needs major welding. Usually where the chain has made a massive hole in the cases, all need fin repairs and general casing repairs but Trig does it himself.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 10, 2018, 09:59:09 PM
I would be welding that damage. Once the spring is under the correct tension it may break the rest of the case.
While the engine is out i would be investigating why the oil is not getting to the top end. It only takes a little sliver of Honda bond to block the oil ways and the jets. Check that you have all the correct 0'rings in place, as one missing or wrong size 0'ring will effect the oil pressure  ;)

If it’s getting to the oil filter but not up to the top does this narrow things down at all? Feel like I’m back to square 1 now if I strip the top end down again!
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on August 10, 2018, 10:13:08 PM
I feel your pain. But, from what you have said, the oil has only got from the pump to the filter. That is about 8 inches  :o
There is no point solving the kick start when you still have other issues.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 10, 2018, 10:20:24 PM
I feel your pain. But, from what you have said, the oil has only got from the pump to the filter. That is about 8 inches  :o
There is no point solving the kick start when you still have other issues.

I’m going to do some more reading on this, there’s a lot of threads out there with people struggling to get pressure after a rebuild and have got round it by fillin from the oil gallery plug on the rhs and pouring lots of oil in the top end. One suggested spending 15 minutes running the starter on and off to build sufficient pressure and some others said they just had to run the engine to get pressure as nothin else worked! Be nice to have a bit more assurance than a suck it and see approach  :o
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on August 10, 2018, 10:35:19 PM
Don't believe everything you read, when it comes to getting pressure up on these engines. Never do it off the starter motor, it will burn it out. Never put oil in the top end, as you will never know if oil is getting there, if it is already put there.
Over the years i have built more than 200 of these engines and i have never failed to get full pressure. I have rebuilt a lot of engines were people have failed to get pressure  ;)

As Bryan and Oddjob will tell you. We call most of these people Sunday mechanics in the trade. They will be in Halfords on a Saturday, try to fit the parts on the Sunday and would be in our workshops on the Monday, asking what went wrong and could we sort it  ;D ;D

You have just got to get in there and get it right. The pro advice is here on this forum  ;)


Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 11, 2018, 01:47:00 PM
Don’t suppose JB weld would have its place in this sort of repair (obviously clutching at straws here!)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 15, 2018, 05:46:04 PM
Been away for a while, managed to grab a quick 30 minutes in the workshop.

Got the pesky roll pin out. As recommended by trigger I tapped it and yanked it out

(https://s8.postimg.cc/s8douuw91/36580204-02_C0-4_CA9-94_BF-7_B4_C276_F441_C.jpg)

Refitted the kickstart correctly. Everything works as it should but half the little ledge the spring sits on is gone.

(https://s8.postimg.cc/82a6vk86t/C243_D81_B-_A652-4_C4_D-867_B-145_B7_ECE1661.jpg)

Going to take it to get a blob of tig weld on there tomorrow. Doesn’t need to be particularly pretty as there’s plenty of clearance around that area
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 17, 2018, 09:05:41 PM
So had a bloke in town put a blob of weld on the broken kickstart spring retainer thing for a few beer tokens. Ground it down with a dremal at home, looks like it will do the trick

(https://s8.postimg.cc/vpmonj76d/E39_D0957-_EB2_C-4_D72-98_F4-_E6139_FDCF63_B.jpg)

Spent most the day scraping old hondabond off with a razor blade trying not to have any fall into the cases. Very boring task! Reapplied the hondabond and closed the cases.

Was struggling to get the gear selector mech back together when I saw this

(https://s8.postimg.cc/mulud0q3p/6619_ECAA-1_CE7-47_D8-926_C-8_EAEE4_D73_F29.jpg)

So annoying! Was probably due to the gear selector dogs not being seated correctly. Had to open up again, spend another eternity prepping the cases and then closing them again.

Got there in the end thought, can hopefully have the lump back in the frame tomorrow
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 17, 2018, 09:18:32 PM
Great, fingers crossed all goes well this time. Just checking.....you did clean out all the swarf after your re modeling with the dremmel ?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 17, 2018, 10:01:04 PM
Great, fingers crossed all goes well this time. Just checking.....you did clean out all the swarf after your re modeling with the dremmel ?

Yeah I covered everything with cling film to stop it getting places and then wiped out where needed

I’ve heard these babies run well on swarf anyway
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 19, 2018, 07:21:47 PM
Made a lot of progress over the last few days, got the engine back in and built the bike back up, getting oil pressure light go out  now after 10 kicks or so which I’m happy with.

Just been doing the points gaps and timing , think I’ve got it as best as I can. Filled some fuel in a remote tank and tried to fire her up but not getting a spark. Condensers were working before strip down.

Any common things I should be checking? I’ll recheck that something crazy hasn’t happened with the points gaps tomorrow, happy with progress but I’m unsure what to look at regarding the sparks

(https://s8.postimg.cc/f0ihjkrat/81_DE1_C8_B-746_E-4_B40-_BF6_E-_AF7_CEF051_B13.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: hairygit on August 19, 2018, 07:35:37 PM
Obviously start with checking all wires you have disturbed, and the connectors are clean and tight, especially the ones where the leads from the points join the main harness, where the rear brake light wires also join the loom. I assume the engine kill switch on the bars is set to the centre position (run)If after that you still get no spark, test for 12v + on the blue then yellow points wires, using the points plate for the 12v - lead. you should get 12v there with ignition on and kill switch in run position.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 19, 2018, 08:30:26 PM
Obviously start with checking all wires you have disturbed, and the connectors are clean and tight, especially the ones where the leads from the points join the main harness, where the rear brake light wires also join the loom. I assume the engine kill switch on the bars is set to the centre position (run)If after that you still get no spark, test for 12v + on the blue then yellow points wires, using the points plate for the 12v - lead. you should get 12v there with ignition on and kill switch in run position.

Thanks mate will work though that in the morning and see where I’m at   ;)
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 19, 2018, 08:41:30 PM
Wow, oil pressure at 10 kicks....thats bloody amazing, well done.
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on August 19, 2018, 08:46:22 PM
Made a lot of progress over the last few days, got the engine back in and built the bike back up, getting oil pressure light go out  now after 10 kicks or so which I’m happy with.

Just been doing the points gaps and timing , think I’ve got it as best as I can. Filled some fuel in a remote tank and tried to fire her up but not getting a spark. Condensers were working before strip down.

Any common things I should be checking? I’ll recheck that something crazy hasn’t happened with the points gaps tomorrow, happy with progress but I’m unsure what to look at regarding the sparks

(https://s8.postimg.cc/f0ihjkrat/81_DE1_C8_B-746_E-4_B40-_BF6_E-_AF7_CEF051_B13.jpg)


How are you going to run the wires for the number light ? I had to run mine inside the swinging arm so not to snag anywhere.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 19, 2018, 09:23:16 PM
Made a lot of progress over the last few days, got the engine back in and built the bike back up, getting oil pressure light go out  now after 10 kicks or so which I’m happy with.

Just been doing the points gaps and timing , think I’ve got it as best as I can. Filled some fuel in a remote tank and tried to fire her up but not getting a spark. Condensers were working before strip down.

Any common things I should be checking? I’ll recheck that something crazy hasn’t happened with the points gaps tomorrow, happy with progress but I’m unsure what to look at regarding the sparks

(https://s8.postimg.cc/f0ihjkrat/81_DE1_C8_B-746_E-4_B40-_BF6_E-_AF7_CEF051_B13.jpg)


How are you going to run the wires for the number light ? I had to run mine inside the swinging arm so not to snag anywhere.

I’ve got one I can fit but after seeing that it’s not an MOT requirement (despite the bike being MOT exempt) I haven’t fitted it yet. Granted that an MOT doesn’t cover all legal requirements if I do put I on illprobably just zip tie the cable on the inner side of the swing arm rather then drill just for ease

Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 19, 2018, 09:30:56 PM
It is required for an MOT and I think it also comes under the C&U (construction and use) regs.
Just because you don't need an MOT you still have to make sure the bike is safe and roadworthy and it won't be either without an illuminated number plate. Read these new MOT regs, digest, learn and comply. Just because you are not getting it tested, doesn't mean you can ride / own an unsafe bike. Use the new MOT regs as the MINIMUM level to aim for.

https://www.mot-testing.service.gov.uk/documents/manuals/class12/
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 19, 2018, 09:34:44 PM
Here is the specific part you need to comply with, copied from the regs.

The rear registration plate must be lit. Most motorcycles will light the registration plate with a rear position lamp, but some will use a separate registration plate lamp.
Some registration plate lamps may be fitted behind the number plate.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 19, 2018, 09:58:24 PM
Here is the specific part you need to comply with, copied from the regs.

The rear registration plate must be lit. Most motorcycles will light the registration plate with a rear position lamp, but some will use a separate registration plate lamp.
Some registration plate lamps may be fitted behind the number plate.

Yeah no dramas thought there was something out there covering it but I saw this https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/449526/mot-inspection-checklist-motorcycle-vt29m.pdf and thought I wouldn’t need to bother

Like I said I’ve got one to go on anyway
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 19, 2018, 10:08:56 PM
Yes, that's just a check list used as a reminder to the MOT tester of what parts he/she needs to look at on an MOT. It's not a list of what's required and what's not required to get your bike through an MOT.
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 19, 2018, 10:10:01 PM
BTW, bikes looking great but the drive chain looks very, very tight, needs about 1" play in it.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 19, 2018, 10:42:24 PM
BTW, bikes looking great but the drive chain looks very, very tight, needs about 1" play in it.

Precisely 22mm at the mid point, checked it earlier  :) :)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 20, 2018, 10:59:16 AM
Wow, oil pressure at 10 kicks....thats bloody amazing, well done.
Just on this I don’t know whether it helped but I poured as much oil as I could into the gallery above the points, might have helped I’m not sure
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 20, 2018, 11:24:15 AM
Wow, oil pressure at 10 kicks....thats bloody amazing, well done.
Just on this I don’t know whether it helped but I poured as much oil as I could into the gallery above the points, might have helped I’m not sure
I think doing that may give you a false reading at the oil pressure switch but those who know alot more than me maybe able to comment further. It's more about getting oil to the top end that is important.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 20, 2018, 02:58:53 PM
It’s a runner! (Well kind of)

https://streamable.com/yyij3

No power to the coils so have jumped them off the battery to get her fired up

Few issues:

Obviously need to sort power to the coils properly
It’s idling at 3k, probably due to mebench syncing with too much thread out the top of the throttle slides (can’t reduce it with idle screw any more)
Intermittently dumping fuel out a few carb overflows which I’m a little confused about as I spent ages setting up floor heights etc and most bits have been replaced.
Clutch not engaging, obviously the bike has been stood a LONG time so presumably the plates are stuck together.

I can figure out most of the above it’s just the clutch, is it worth bumping in first and taking on a little ride to see if it unstick or is this always a strip down and rebuild job?
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 20, 2018, 03:04:40 PM
Well done. Take the tappet covers off to see if oil is spitting out and maybe you should locate the tacho drive cable in correctly 🙂🙂🙂
Title: Re: CB750 Barn find project - First Timer
Post by: hairygit on August 20, 2018, 03:05:57 PM
As regards power to the coils, check that you have 12v reaching the kill switch on the bars (inside headlamp). As regards the clutch, it's not a difficult job to strip it out and free it off, and far safer than bumping it and hoping it will free off, especially if you have hotwired the coils!
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 20, 2018, 03:34:57 PM
Well done. Take the tappet covers off to see if oil is spitting out and maybe you should locate the tacho drive cable in correctly 🙂🙂🙂

Already done the tappets and there’s oil spitting about in there  :D with regards to the tacho cable it’s a super cheap one from mandp and isn’t a very good fit despite them saying it fits the bike

As regards power to the coils, check that you have 12v reaching the kill switch on the bars (inside headlamp). As regards the clutch, it's not a difficult job to strip it out and free it off, and far safer than bumping it and hoping it will free off, especially if you have hotwired the coils!

Nice one mate that’s why we ask these questions (so I don’t end up in my neighbours hedge!)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 24, 2018, 06:05:15 PM
Today was a good day

Found that one of the kill switch wires was going into the lighting circuit rather than to black, sorting that out sorted the power to the coils, not sure how I missed that the other day!

Popped the clutch out and rubbed down each of the metal plates with 600 grit, plenty of wear left all round so just reinstalled and voila, my clutch is working.

Popped the tank and seat back on along with some half painted side covers and took her out for her maiden voyage (private road of course). All seems great, apart from a lumpy idle, carbs haven’t been synced so that may help but I don’t think pods do the idle any favours, had to set it to >1000rpm to avoid stalling. Brakes need adjusting but no real dramas there.

Was very surprised with how nicely it pulls especially as I’ve just stuck #42 and #120 jets in there as just somewhere to start, was fully expecting It to be rough whilst I dialled it in.

Where’s best to go from here with the carbs - sync them and get some miles on the clock and then note down flat spots etc check  plug colour and adjust from there?

Also one or two carbs are overflowing when the engine is switched off, floats aren’t stuck and the pins are nice and clean, any usual suspects to look out for?

(https://s8.postimg.cc/ajztjiqhh/CAA2_D2_EC-1012-4245-83_F4-52_F707_FF0_CC9.jpg)


Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on August 24, 2018, 06:31:47 PM
There are  only a few reasons for carb overflow,,
Float height incorrect
Bad needle tip/seat
Crack in brass standpipe inside float bowl
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 24, 2018, 08:44:30 PM
There are  only a few reasons for carb overflow,,
Float height incorrect
Bad needle tip/seat
Crack in brass standpipe inside float bowl

The carbs have been fully rebuilt with a cruzin image kit, I set the floats to 26mm above the carb body, no cracks in any standpipes.

It’s intermittent and seems to happen after I shut the engine off which in my head makes me think potential stuck float - maybe there’s a burr or something.

Will have to get the bowls off again and have another look, for now I’m just turning the pet cock off when I stop
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on August 24, 2018, 09:29:15 PM
Nice work ud!... getting there  8)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 25, 2018, 08:49:26 AM
Nice work ud!... getting there  8)

Painted the side covers late yesterday and have contacted a local upholsterer ability making a seat cover (unfortunately my friend isn’t able to do it).

Also I’ve insured it with Go Skippy. £90.97 fully comp with only a £50 excess. Wasn’t sure on value so I stuck 4.5k down (gotta be optimistic!). Strangely you can find these old bikes on a  lot of comparison sites and on others where you have to put the VRN in it was coming up as some 400cc Suzuki..!? Double checked my paperwork from the DVLA and it’s all correct
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 25, 2018, 09:36:55 AM
Your bike reg number actually comes up on DVLA as a 400 Yamaha, registered in UK May 18 Something not quite right there. Have you insured it as a Honda 750 or a Yam 400?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 25, 2018, 10:47:27 AM
Your bike reg number actually comes up on DVLA as a 400 Yamaha, registered in UK May 18 Something not quite right there. Have you insured it as a Honda 750 or a Yam 400?
As a Honda 750. I’ve checked my DVLA paperwork and it all checks out so I’ll give them a call in case they’ve made a mistake on their system somewhere.

Had the old girl out again this morning, keeps dying after 10-15 mins and then doesn’t want to run until it’s cooled down.

Is this likely to be battery related? Don’t think it was fully charged when I set off but doesn’t make sense why it would spring back to life after cooling down. The other thing that has crossed my mind is air leaks around the carbs opening up when things start expanding?
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on August 25, 2018, 04:14:21 PM
Conking out after 15 mins then not starting till cooled down sounds like an electrical component failing at higher temperature... coil maybe. Or it could be fuel starvation but unlikely....
Title: Re: CB750 Barn find project - First Timer
Post by: sye on August 25, 2018, 04:38:58 PM
Could be  vacuum in the tank caused by a blocked breather. Take the fuel cap off when it conks out and if air rushes in it could be the culprit.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 25, 2018, 05:13:09 PM
Conking out after 15 mins then not starting till cooled down sounds like an electrical component failing at higher temperature... coil maybe. Or it could be fuel starvation but unlikely....

Could be the condensers, they are the original ones.

Didn’t have any tools with me to check the spark, was thinking at the time it would be ideal to have a spare spark plug in my pocket as I could do it with no tools
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 25, 2018, 07:08:54 PM
Could be  vacuum in the tank caused by a blocked breather. Take the fuel cap off when it conks out and if air rushes in it could be the culprit.
Tried this at the time, didn’t make a difference
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on August 25, 2018, 07:25:43 PM
Not too rich is it? Just chokes it when warm possibly.
What colour are the plugs?  Do they indicate rich setting or the opposite?

If rich,  crank it with throttle wide open to get more air in and it may go.

There are breathers into the float chambers of each carb that allow the fuel level to stabilise,  you can run into problems with filling if these are not all clear.

As a means of diagnosis,  when it stops you can open the throttle and spray some easy start into the carbs via the filters to see if it'll fire again straight away.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 25, 2018, 09:03:40 PM
Not too rich is it? Just chokes it when warm possibly.
What colour are the plugs?  Do they indicate rich setting or the opposite?

If rich,  crank it with throttle wide open to get more air in and it may go.

There are breathers into the float chambers of each carb that allow the fuel level to stabilise,  you can run into problems with filling if these are not all clear.

As a means of diagnosis,  when it stops you can open the throttle and spray some easy start into the carbs via the filters to see if it'll fire again straight away.

Just popped back out to ensure the battery was charging properly and it roared to life on the button no problems.

I did try cranking it with open throttle when I was stranded earlier and anything it seemed even more reluctant to start some how. By breathers into each float chamber do you mean the little tubes that join each carb bowl pair together (connected by a rubber tube)? I was meticulous in cleaning the carbs - soaked in carb cleaner, scrubbed, wire pushed through holes, multiple passes fully stripped down in a US cleaner, blew through with compressed air rebuilt with all new bits etc..

I’ll check the plugs out tomorrow, jetting is probably out and they haven’t been synced yet.

What’s a symptom of a dodgy condenser?
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on August 25, 2018, 09:25:41 PM
Condenser is there to in effect "buffer" the the electric load being switched by the points.

As the points open to break the earth contact to the coils (this starts the HT spark travel from the coils to plugs) the voltage wants to jump across the points gap as it's very small at the start of opening. The condenser absorbs this affect (stops the sparking) to give a clean switching of the points circuit.

If the condenser is inefficient,  then the spark across the points will increase.  If you got such a bad jump across there it would not be switching the coils as they would still be earthed.

Unlikely to get both failed together but I guess possible. 
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on August 25, 2018, 09:46:01 PM
In other words, if you take the points cover off and run the motor and the points are visibly sparking like mad then the condenser is knackered, if they aren’t its ok.  :)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 25, 2018, 11:39:17 PM
Nice one for thebasgice on checking points guys.

I’d like to get the bike back to the same state to see if it stops getting a spark. I’m aware these bikes get very hot when idling and I don’t want to damage anything, but I’m thinking about leaving the bike idle away until It cuts out so I can test the spark at home rather than take it for a ride and brake down somewhere..

If the sparks good when it dies then I guess that rules out electrical stuff. I could try easy start around the carb boots too when it heats up to see if there are any leaks
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on August 26, 2018, 09:45:23 AM
Rob's right, loads of sparks they need to by changed.
To add,  when very bad they are reluctant to start very well which you don't initially have. 

Float bowl breathers, you're right that it's the paired vents into the chambers that allow pressure neutralising.  You should be able to blow into them to see if they aren't clear as a quick and dirty check.

I wouldn't worry about heat build up at tickover on these,  I've been in bike jams into race circuit on a hot day for much longer than that. They don't really overheat as such but probably abit hotter than ideal.

It still looks like fuel to me unless you can eliminate something else. They'll run close to 5 miles on full float bowls with fuel tap turned off if going gently.
To progress that theory of slow or restricted filling, when it stops, turn off fuel and remove one outer float bowl to see if you have fuel there or not. Think you can just get them off with a stubby screwdriver. 
That was what I was aiming at with the easy start test...... No fuel scenario, add flammable to carb throats,  if you get response then it would confirm....I wouldn't put easy start around the outside of a hot engine as you may set it alight!

Have you got a good flow of fuel from tank outlet? Again, if you can get a float bowl off you can see how quick the fuel is flowing through the entire delivery system from tank to destination.
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on August 26, 2018, 10:30:57 AM
This kind of fault can be difficult to diagnose.... if its fuel starvation and you go through all the various components to ensure they aren’t blocked or damaged you will eventually eliminate it. For an electrical fault it will also be a process of eliminating the faulty component. If an electrical component is damaged, cracked, broken etc as it warms up it can lose connection then as it cools it reconnects.... so the only real way to diagnose it is to replace components one at a time until you solve the problem. The condensers are so cheap they should be changed anyway, if that works then its a cheap result... i would suspect the coils but it could be anything. Does it stop dead or begin to missfire and die gradually?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 26, 2018, 01:45:28 PM
This kind of fault can be difficult to diagnose.... if its fuel starvation and you go through all the various components to ensure they aren’t blocked or damaged you will eventually eliminate it. For an electrical fault it will also be a process of eliminating the faulty component. If an electrical component is damaged, cracked, broken etc as it warms up it can lose connection then as it cools it reconnects.... so the only real way to diagnose it is to replace components one at a time until you solve the problem. The condensers are so cheap they should be changed anyway, if that works then its a cheap result... i would suspect the coils but it could be anything. Does it stop dead or begin to missfire and die gradually?
It dies gradually, seems like it’s not pulling properly and then stops acellerating but will maintain speed if I stay on the throttle, as soon as the throttle let off it dies.

I’m going to order new condensors, I assume the DS repro ones are ok? What about his repro coils?
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on August 26, 2018, 02:39:56 PM
The gradual thing doesn’t sound electrical to me..... I have new ds condensers on my k4, one of them failed after 50 miles (missfiring and spaarking like hell under the points cover) so I can’t recommend those... I’m wondering if its fuel or worse still mechanicsl. Have you checked valve clearances and compression?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 26, 2018, 02:47:07 PM
The gradual thing doesn’t sound electrical to me..... I have new ds condensers on my k4, one of them failed after 50 miles (missfiring and spaarking like hell under the points cover) so I can’t recommend those... I’m wondering if its fuel or worse still mechanicsl. Have you checked valve clearances and compression?
Set the valve clearance when I rebuilt, haven’t checked compression but everything was within spec,barrels were honed and rings replaced.

Could be fuel flow as I’m getting random carb bowl overflows.. will have time tomorrow to check it all.

I’ve got a hondaman ignition module to go on but I want to have it running sweet before I add more things into the mix
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on August 26, 2018, 02:50:46 PM
Ps if you want repro coils try the ones from wemoto......much cheaper and work well i can vouch for those!
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on August 26, 2018, 02:55:02 PM
Check compression! Burned or leaky valves could be an issue.... build up of carbon on the stems can cause the valves to stay open once warmed up  (i had this issue back in the 80’s)... a re-lap of the valve seats transformed the motor. A compression test will help, when cold and also at running temp... keep going, you will get there.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 26, 2018, 02:57:17 PM
Check compression! Burned or leaky valves could be an issue.... build up of carbon on the stems can cause the valves to stay open once warmed up  (i had this issue back in the 80’s)... a re-lap of the valve seats transformed the motor. A compression test will help, when cold and also at running temp... keep going, you will get there.
Ok sounds easy enough, lapped all the valves and cleaned hem up during the rebuild but I’ll recheck clearances and do a compression test this week.. just need a compression gauge.

Are the cheap ones that come in a red plastic case (all over amazon and eBay) for about £12 good enough?
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 26, 2018, 03:10:11 PM
10-15 minutes riding sounds quite a long time for something fuel or electrical related to show itself. Could it be the top end of the engine getting very hot for some reason and partially seizing due to metal expansion? Cools down, contracts and off you go again. My theory is based on nothing more than Women's logic here 😁😁
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 26, 2018, 03:19:10 PM
10-15 minutes riding sounds quite a long time for something fuel or electrical related to show itself. Could it be the top end of the engine getting very hot for some reason and partially seizing due to metal expansion? Cools down, contracts and off you go again. My theory is based on nothing more than Women's logic here 😁😁
I had something that felt similar on a hornet I had, would conk out after 15 mins and not restart until it cooled down, was a burnt connector from the stator and a duff rectifier causing the battery to not charge.

I get 14.5v over the battery with bike on or off which seems fine. Would be good to rest when the battery is depleted a bit I suppose to make sure the voltage jumps up when it starts

Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on August 26, 2018, 03:22:57 PM
The 12 quid ones are crap mate
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 26, 2018, 08:02:57 PM
The 12 quid ones are crap mate
Maybe I’ll stretch to the £18 ones then :D

Not had time to work on the bike today but quickly whipped the carb bowls off and fuel flows fine, embarrassingly I thought  the off and reserve settings on the pet cock were the other way round so half the time I was probably trying to start the bike in the off position!

Now it’s even possible that I ran out of fuel on the on position as I put a Jerry cans worth of fuel in  then continued to try and start the bike in the off position and I did fanny about with the peacock a fair bit during breakdowns, perhaps I filled the carb bowls up when I though it was switched off and then drove a mile or so with it actually switched off thinking I was on reserve until the bowls emptied again..

Anyway I can’t see any sparks at all at the points one of the spark plugs seemed loose and this is the colour they’re at

(https://s15.postimg.cc/qln1zqg0r/036869_AB-1_C04-4425-_A392-5_DA9_CECE65_C7.jpg)
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on August 26, 2018, 08:19:12 PM
Lol... hopefully you have solved the mystery...  :)
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on August 26, 2018, 08:23:13 PM
I know you have a few issues to attend too but it must be a good feeling that she's up and running now. We'll done.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 26, 2018, 08:32:32 PM
I know you have a few issues to attend too but it must be a good feeling that she's up and running now. We'll done.

Yeah it’s been a great learning experience, never messed about with engines before but now feel as if I’ve at least got a basic grasp!

When I do the next one it will be a lot easer  :)
Title: Re: CB750 Barn find project - First Timer
Post by: SteveD CB500K0 on August 27, 2018, 07:16:50 AM
I did fanny about with the peacock a fair bit during breakdowns

I should resurrect the old “Quote of the Month” thread



Sent from my iPhone using Tapatalk
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on August 27, 2018, 08:26:41 AM
Plug doesn't look crazy,  bit dark but the main electrode is burning clean-ish so not too far off and would probably show better if it ran for longer.

They really will do over 3 miles on one fill of the float bowls as I routinely turned mine off on the way home to leave it parked as good habit when riding them.

Hope you've found the reason and nailed that one down.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 27, 2018, 09:18:10 AM
I did fanny about with the peacock a fair bit during breakdowns

I should resurrect the old “Quote of the Month” thread



Sent from my iPhone using Tapatalk
Hah peacock! Bloody iPhone autocorrect always makes me post weird stuff  ;D
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 27, 2018, 09:26:58 AM
Plug doesn't look crazy,  bit dark but the main electrode is burning clean-ish so not too far off and would probably show better if it ran for longer.

They really will do over 3 miles on one fill of the float bowls as I routinely turned mine off on the way home to leave it parked as good habit when riding them.

Hope you've found the reason and nailed that one down.

Will be nice if it’s that simple, going to to some laps of the block so if I break down I won’t be too far and also bring a backpack full of tools to check plugs, fuel, coils, battery etc.

As I mentioned earlier the carbs have only been bench synced, needle clips are in the middle position so could move  them down a notch or two to raise the needle for a leaner mix. I’ve ordered a carbtune pro to properly sync them too.

I’m happy I’m in the ballpark with the jets as it was basically a guess
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 27, 2018, 01:25:48 PM
Seemed ok on a 15 minute ride, came back in as the front brake was feeling pretty absent. I’ve got braided lines and a rebuilt caliper (reused the piston as it seemed ok) and new master cylinder, it’s been ok up until now but just felt like it wasn’t stopping the bike to the point where I met a car in the lanes and had to use the rear brake heavily to stop. Haven’t yet adjusted it as I can’t get the front wheel in the air without taking the headers off which means new crush gaskets, will get around to it soon though but I think it’s maybe more than just out of adjustment. It’s been bled properly and the lever is feeling hard.

Something else I’ve noticed is one of the oil lines has a small drip where the end fixing is crimped on. I take it this can’t be overhauled?

(https://s8.postimg.cc/m42ct3h0l/73_E46369-0362-4871-9786-_E03_B3_D8_D3_F11.jpg)

With regards to the carbs overflowing, I fitted the overflow hoses and since then not had anything out of them, can’t see why that would make a difference though.

UPDATE: just seen the price of those oil hoses  :o
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 01, 2018, 05:03:32 PM
So thankfully it seems it’s the washer on the oil tank drain bolt leaking rather than the oil hose, I’ll replace the washer at some point and see if it makes a difference.

The seats currently with a local upholsterer getting sorted, have received a Morgan carbtune pro so I’ll hopefully have the carbs dialled in soon (unable to work on it this weekend though).

The carbs are still dumping fuel seemingly randomly. I’ll put the bike away and switch the fuel off, tinker around with a few things and still no fuel dumped.. but when I come back into the garage the next day there will be fuel ok the floor. Sometimes it doesn’t happen for a few days and all of a sudden it justs dumps the fuel whilst sat doing nothing...

They floats seem ok, if they were at incorrect heights or whatever surely it would just overflow straight away?
Title: Re: CB750 Barn find project - First Timer
Post by: Honda Al on September 01, 2018, 07:13:35 PM
So thankfully it seems it’s the washer on the oil tank drain bolt leaking rather than the oil hose, I’ll replace the washer at some point and see if it makes a difference.

The seats currently with a local upholsterer getting sorted, have received a Morgan carbtune pro so I’ll hopefully have the carbs dialled in soon (unable to work on it this weekend though).

The carbs are still dumping fuel seemingly randomly. I’ll put the bike away and switch the fuel off, tinker around with a few things and still no fuel dumped.. but when I come back into the garage the next day there will be fuel ok the floor. Sometimes it doesn’t happen for a few days and all of a sudden it justs dumps the fuel whilst sat doing nothing...

They floats seem ok, if they were at incorrect heights or whatever surely it would just overflow straight away?

I’ve had this recently on my 500. At first I thought I left the fuel tap on, but realised that the fibre washers in the petcock housing had failed and were leaking fuel through the tap down into the carbs. They would then overflow onto the garage floor.

Quick test is to lift the fuel tank, and place it on a flat surface with a tray under the petcock. If the petcock is switched off but fuel starts gathering in the tray, there’s the source of the problem.

Hope this helps.


Sent from my iPhone using Tapatalk
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 01, 2018, 10:20:31 PM
So thankfully it seems it’s the washer on the oil tank drain bolt leaking rather than the oil hose, I’ll replace the washer at some point and see if it makes a difference.

The seats currently with a local upholsterer getting sorted, have received a Morgan carbtune pro so I’ll hopefully have the carbs dialled in soon (unable to work on it this weekend though).

The carbs are still dumping fuel seemingly randomly. I’ll put the bike away and switch the fuel off, tinker around with a few things and still no fuel dumped.. but when I come back into the garage the next day there will be fuel ok the floor. Sometimes it doesn’t happen for a few days and all of a sudden it justs dumps the fuel whilst sat doing nothing...

They floats seem ok, if they were at incorrect heights or whatever surely it would just overflow straight away?

I’ve had this recently on my 500. At first I thought I left the fuel tap on, but realised that the fibre washers in the petcock housing had failed and were leaking fuel through the tap down into the carbs. They would then overflow onto the garage floor.

Quick test is to lift the fuel tank, and place it on a flat surface with a tray under the petcock. If the petcock is switched off but fuel starts gathering in the tray, there’s the source of the problem.

Hope this helps.


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Thanks for the advice but as this has happened with a remote fuel tank too I don’t think it’s petcock related
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on September 02, 2018, 09:58:22 AM
I had the leaking oil line problem..... apparently the oil lines rarely fail so i messed about with various washers but to no avail. I ended up having the oil line re-hosed at mendahose (not for the purist but very cheap and looks great imo).... solved the problem and a week later the 2nd hose also started dripping so i had that re-hosed exactly the same. Now both ok and look great, cost £35 each. You can get original looking pipes from dss for £300 ! Or they can be re-tubed back to standard but I think you would be happy with pipes done at mendahose or some other similar industrial hydraulic repair shop...http://www.mendahose.co.uk (http://www.mendahose.co.uk)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 02, 2018, 05:21:15 PM
So thankfully it seems it’s the washer on the oil tank drain bolt leaking rather than the oil hose, I’ll replace the washer at some point and see if it makes a difference.

The seats currently with a local upholsterer getting sorted, have received a Morgan carbtune pro so I’ll hopefully have the carbs dialled in soon (unable to work on it this weekend though).

The carbs are still dumping fuel seemingly randomly. I’ll put the bike away and switch the fuel off, tinker around with a few things and still no fuel dumped.. but when I come back into the garage the next day there will be fuel ok the floor. Sometimes it doesn’t happen for a few days and all of a sudden it justs dumps the fuel whilst sat doing nothing...

They floats seem ok, if they were at incorrect heights or whatever surely it would just overflow straight away?

I’ve had this recently on my 500. At first I thought I left the fuel tap on, but realised that the fibre washers in the petcock housing had failed and were leaking fuel through the tap down into the carbs. They would then overflow onto the garage floor.

Quick test is to lift the fuel tank, and place it on a flat surface with a tray under the petcock. If the petcock is switched off but fuel starts gathering in the tray, there’s the source of the problem.

Hope this helps.


Sent from my iPhone using Tapatalk
Thanks for the advice but as this has happened with a remote fuel tank too I don’t think it’s petcock related
Well the bike has been standing a week and it still looks like fresh fuel is coming out the overflows despite petcock being switched off also one or two of the overflow tubes themselves are falling apart at the ends.. is this ethanol related?

(https://s15.postimg.cc/sc07clq3v/840_EAAC2-_DD1_C-4_B2_E-_B97_C-53_A70088_E44_C.jpg)

Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on September 02, 2018, 05:29:39 PM
Take the float bowl off and secure it level,  fill with fuel and see if it drops then.

You can get the internal brass "standpipe" tube cracked and it let's the fuel leak out even without breaching the float/fuel level.

Check each in turn to find any errors.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 02, 2018, 06:41:53 PM
Take the float bowl off and secure it level,  fill with fuel and see if it drops then.

You can get the internal brass "standpipe" tube cracked and it let's the fuel leak out even without breaching the float/fuel level.

Check each in turn to find any errors.

Just to clarify you mean fill up the carb bowl when they are off the bike?
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on September 02, 2018, 07:45:02 PM
Yes.

They sometimes get a crack in the tube that allows the fuel out through the overflow pipe without the level of fuel being above the top of that brass tube.

It would do as you indicate by leaking out even if the fuel tap is turned off.
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on September 03, 2018, 12:46:00 AM
If it is leaking with the tap turned off either the tap sealing disc is duff or you did not fit the proper washers under the heads of the retaing bolts
Title: Re: CB750 Barn find project - First Timer
Post by: yozzer74 on September 03, 2018, 04:23:58 PM
I had this problem mine was the over flow tube had a crack in it couldn't see it but it leaked .I fitted a piece of rubber tube over it think it was 4mm had no trouble after.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 03, 2018, 06:46:28 PM
If it is leaking with the tap turned off either the tap sealing disc is duff or you did not fit the proper washers under the heads of the retaing bolts
I just usescooper washers - didn’t look like anything special when I replaced them
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on September 04, 2018, 07:32:13 AM
There is your problem as they should be thick fibre washers that you can not get genericaly. I have used 6mm "Dowty" style washers with some success. If a total seal does not happen fuel leaks down past the bolt threads and bypasses the tap flooding the float bowls
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 04, 2018, 05:05:16 PM
There is your problem as they should be thick fibre washers that you can not get genericaly. I have used 6mm "Dowty" style washers with some success. If a total seal does not happen fuel leaks down past the bolt threads and bypasses the tap flooding the float bowls
Aha nice that would explain part of it, but the bowls overflowing is a separate issue I think

UPDATE: just under £14 to have 2 delivered from DS..
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on September 04, 2018, 05:20:23 PM
As above,  even with fuel tap leaking (if confirmed)  the float bowls should be limited by the float closing the supply with needle valve.

I know they can be iffy,  but if all clean they generally work ok.

I'd still work to confirm those internal "weir" tubes are not leaking.  If you have just one (put each one into a jamjar to verify)  then swap float bowl with another to see if problem switches with it.
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on September 05, 2018, 02:13:37 AM
With hravity feed from tank and engine off float needles have to be perfect to stop flow. With screws sealed you should not get more leakink and floats will seal enough for normal running as long as you remember to turn off when stopping engine. I think this was one of the reasons vac taps became more common
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 05, 2018, 07:49:25 PM
With hravity feed from tank and engine off float needles have to be perfect to stop flow. With screws sealed you should not get more leakink and floats will seal enough for normal running as long as you remember to turn off when stopping engine. I think this was one of the reasons vac taps became more common

Yeah will investigate further this weekend, have ordered a few of those dowty washers you mentioned, will hopefully have some luck. The seats at the upholsterers so can’t ride anyway
Title: Re: CB750 Barn find project - First Timer
Post by: Bryanj on September 05, 2018, 11:06:11 PM
If using dowty washers you might get better results using allen bolts instead of screws as the underside of the head is better
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 09, 2018, 09:04:43 AM
Finally going to have some fettling time today so going to sort the petcock and carbs.

Running on the rich side so need to raise the needle clip either 1 or 2 notches. How long do I need to run the bike for before looking at plug colour again to see if I need to move needle position again? And do I need to clean up the plugs if they’re already a bit blackened from rich running or does this get burnt off?
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 09, 2018, 08:10:32 PM
Okay so pulled the carbs off and raised the needle clips one notch to lean out the mix a bit, I’m at one clip from the top so still got some further adjustment if needed. Checked the floats and they are all bang on 26mm and operate smoothly. I’ve replaced the float valves with the original ones incase the cruzin image ones aren’t sealing properly. The aftermarket ones go into a point whilst the original ones are blunted off at the tip. I also noticed that the air mixture screws were no longer at the 1 turn out, on was at about 3 turns out.. no idea how these have worked themselves out but put them back to 1 turn.

Got them back on the bike and synced with a carbtune pro which was pretty easy but then noticed I had a significant leak around the front sprocket cover. Whipped the sprocket off and seen this

(https://s15.postimg.cc/varjcemff/01123_F7_C-_CEF3-4971-8_A96-11755828_B953.jpg)

The drive seal wasn’t sitting flat as it should and was leaking at the bottom where it protruded out slightly. Unsure whether it wasn’t lined up correctly when I closed the cases or not but it’s not leaked for the first 50 miles until now. I even put a smear of hondabond on it as recommended in hondamans book so perhaps this held back the oil until now.

Rightly or wrongly I carefully tapped it back in flush and it doesn’t seem to leak any more. Am unable to ride as the seats with the upholsterer but fingers crossed it’s fine

Still getting a bit out the overflows so don’t think swapping the float valves has done anything. I’ve not got any sort of washer beneath the float valve seat and carb body, none was supplied in the rebuild kit and none were on it when I stripped them.. have seen in some pictures that some sort of washer is present - did this appear on certain years only or am I missing them possibly?
Title: Re: CB750 Barn find project - First Timer
Post by: Laverda Dave on September 09, 2018, 08:19:25 PM
I feel your pain underdog :(. I suffered a similar fate with my CB250RSA drive oil seal. It was fine for 10 miles and then just let go in the same way dumping oil all over the road. I had to split the cases to replace the seal. Hopefully yours will be OK, good luck.
Title: Re: CB750 Barn find project - First Timer
Post by: Trigger on September 09, 2018, 08:24:28 PM
Do your air screws have springs ? They should not move ;)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 09, 2018, 08:41:45 PM
I feel your pain underdog :(. I suffered a similar fate with my CB250RSA drive oil seal. It was fine for 10 miles and then just let go in the same way dumping oil all over the road. I had to split the cases to replace the seal. Hopefully yours will be OK, good luck.
Yeah time will tell, it’s a new seal so no idea why it’s happened.

Do your air screws have springs ? They should not move ;)

Yeah they do, it’s possible I had a brain fart at some point but I’ll keep an eye on them to see if they move at all in the future
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 14, 2018, 08:45:33 AM
Seats got covered, upholsterer text me yesterday but not managed to pick it up yet

(https://s22.postimg.cc/qpjqboi4h/E5_AA054_B-_CF55-493_C-_A398-_A209_B1_A4_D2_A8.jpg)

Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on September 14, 2018, 09:14:26 AM
Very nice.
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 15, 2018, 06:33:26 PM
Seats fitted and took the bike out for a spin. Have also had a fiddle with and synced the carbs

(https://s15.postimg.cc/u2sz6k4jv/586_A4712-_E71_A-42_DD-_BE17-_EED60256_F836.jpg)

I think it looks great and is just what I wanted. Bikes running alright still a little stumble at 3.5k but I’ve got another needle clip position to try in the future. The front sprocket oil seal is now doing its job since tapping it into place but will keep an eye on it, just getting some drips from one of thof oil hoses which I’ll look at getting repaired when I change the oil.

Since replacing the washers on the fuel tap with dowty style ones as recommended by Bryan I’m not getting any more leakage through the petcock, I am however still getting overflowing carb bowls when the fuel tap is left on, just dribbles out. Have tested the brass overflow pipes for cracks and they’re all good, have swapped the replacement float valves with oem ones but still no joy. Pushing the floats up by hand stops the flow of fuel when the bowls are off
Title: Re: CB750 Barn find project - First Timer
Post by: Nurse Julie on September 15, 2018, 07:18:26 PM
Well done you, it looks great and its a real credit to you. I know you have had plenty of agro and dramas along the way and I'm sure there will still be little problem that pop up and need sorting but that's old bikes for you. Enjoy.
Oh and make sure its totally legal and safe, Mr Plod just loves to pick on something a bit different !!!
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 15, 2018, 08:34:23 PM
Well done you, it looks great and its a real credit to you. I know you have had plenty of agro and dramas along the way and I'm sure there will still be little problem that pop up and need sorting but that's old bikes for you. Enjoy.
Oh and make sure its totally legal and safe, Mr Plod just loves to pick on something a bit different !!!
Thanks Julie! Been a steep learning curve as I’ts my first time dabbling with engines and before I started this thread I don’t think I even owned a set of sockets.. I’ve now got a pretty well equipped workshop.

Big thanks to you, Graham, Bryan and all the others who’ve given me help along the way, few last bits of tinkering and that should be his thread closed. Only took 2 years  ;D
Title: Re: CB750 Barn find project - First Timer
Post by: Wenman on September 15, 2018, 08:54:29 PM
Love it well done bud! Let me know if ur ever riding it down south! I’ve not long completed my 550 brat/cafe which looks very similar!

Alan
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 15, 2018, 09:12:09 PM
Love it well done bud! Let me know if ur ever riding it down south! I’ve not long completed my 550 brat/cafe which looks very similar!

Alan

I’m in the south west between taunton an Axminster, where abouts are you?
Title: Re: CB750 Barn find project - First Timer
Post by: Wenman on September 15, 2018, 11:57:49 PM
Torquay bud!!!

Don’t suppose you are par taking in the gentlemen’s ride out from Exeter on the 30th are you!

Small world eh!

Be great to meet for some rides!!

Al
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on September 16, 2018, 08:47:22 AM
Nice work, looks good out in the wild  :)

Riding these bikes when contemporary it was kind of habitual to shut the fuel off just before end of journey to avoid chance of carbs leaking.  Generally they didn't but it was just good practice at the time so not too unusual.

Something that may help though, I think It was Kevski that described lapping in gently the brass needle valves to get a good seal with the carb.  I've forgotten what he's suggested so if reading this may get it explained more thoroughly for you.

Hope you enjoy riding it after all your hard work.
Title: Re: CB750 Barn find project - First Timer
Post by: philward on September 16, 2018, 12:34:54 PM
Seats fitted and took the bike out for a spin. Have also had a fiddle with and synced the carbs

(https://s15.postimg.cc/u2sz6k4jv/586_A4712-_E71_A-42_DD-_BE17-_EED60256_F836.jpg)

I think it looks great and is just what I wanted. Bikes running alright still a little stumble at 3.5k but I’ve got another needle clip position to try in the future. The front sprocket oil seal is now doing its job since tapping it into place but will keep an eye on it, just getting some drips from one of thof oil hoses which I’ll look at getting repaired when I change the oil.

Since replacing the washers on the fuel tap with dowty style ones as recommended by Bryan I’m not getting any more leakage through the petcock, I am however still getting overflowing carb bowls when the fuel tap is left on, just dribbles out. Have tested the brass overflow pipes for cracks and they’re all good, have swapped the replacement float valves with oem ones but still no joy. Pushing the floats up by hand stops the flow of fuel when the bowls are off
Nice job - all your hard work has paid off
Title: Re: CB750 Barn find project - First Timer
Post by: Rob62 on September 16, 2018, 02:16:25 PM
Great job UD!.... all your hard work and problem solving paid off in the end.... enjoy the indian summer  :)
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on September 29, 2018, 06:49:07 PM
Finally going to have some fettling time today so going to sort the petcock and carbs.

Running on the rich side so need to raise the needle clip either 1 or 2 notches. How long do I need to run the bike for before looking at plug colour again to see if I need to move needle position again? And do I need to clean up the plugs if they’re already a bit blackened from rich running or does this get burnt off?

I raised the needle clip one position and didn’t really see a difference. Today I changed the main jets from #120 down to #110 leaving the needle position the same, was hoping to see a difference either good or bad but literally feels exactly the same with the flat spot at 3.5-4krpm. As I’ve said before I appreciate with pods it will never run as well as with an air box but I thought I would at least feel the difference of a significant change in jetting?
Title: Re: CB750 Barn find project - First Timer
Post by: K2-K6 on September 29, 2018, 08:35:51 PM
It's more or less the transition point (under light throttle opening)  of the idle circuit going fully to main jet running. Because the mods make the vacuum gradient go a bit chunky then it's this bit that is hard to define regarding jetting and making decisions about it.  It will be hard to decipher so needs alot of trial and error to get improvements.

Could start as it is by trying it with the idle screws turned in 1/2 turn to see what it does. Then do the opposite, 1/2 turn out and try it to see what you can feel when riding. That's both from the original idle screw start point, 1 turn out? Ish?

Make sure the plug gaps are very concise on their minimum gap, which plug's are you running?
Title: Re: CB750 Barn find project - First Timer
Post by: Laverda Dave on September 29, 2018, 10:31:37 PM
Great Job and nice looking shortie exhaust. Now you've completed your first bike you've probably been bitten by the bug  :). I agree with Nigel, always turn the fuel off before you finish your ride to stop the incontinent carbs dribbling!
Title: Re: CB750 Barn find project - First Timer
Post by: MarkCR750 on September 30, 2018, 05:00:51 PM
Great looking machine UD, well done, pound to a penny it’s the pods causing the stumble, stick some velocity stacks on it.
Title: Re: CB750 Barn find project - First Timer
Post by: Mag1 on January 01, 2019, 04:50:52 PM
Seats fitted and took the bike out for a spin. Have also had a fiddle with and synced the carbs

(https://s15.postimg.cc/u2sz6k4jv/586_A4712-_E71_A-42_DD-_BE17-_EED60256_F836.jpg)

I think it looks great and is just what I wanted. Bikes running alright still a little stumble at 3.5k but I’ve got another needle clip position to try in the future. The front sprocket oil seal is now doing its job since tapping it into place but will keep an eye on it, just getting some drips from one of thof oil hoses which I’ll look at getting repaired when I change the oil.

Since replacing the washers on the fuel tap with dowty style ones as recommended by Bryan I’m not getting any more leakage through the petcock, I am however still getting overflowing carb bowls when the fuel tap is left on, just dribbles out. Have tested the brass overflow pipes for cracks and they’re all good, have swapped the replacement float valves with oem ones but still no joy. Pushing the floats up by hand stops the flow of fuel when the bowls are off

That is a great looking bike you should be proud of, been away a lot myself and need to complete mine, been on the back burner now for nearly 2 years, just the wiring, fuel system to redo, poss a new tank as mine as the pin hole syndrome and needs re-stripped. This has given me the jump start again to do mine. Thanks for sharing your build.
Title: Re: CB750 Barn find project - First Timer
Post by: gp_st3 on January 01, 2019, 05:02:50 PM
Got them back on the bike and synced with a carbtune pro which was pretty easy but then noticed I had a significant leak around the front sprocket cover. Whipped the sprocket off and seen this

(https://s15.postimg.cc/varjcemff/01123_F7_C-_CEF3-4971-8_A96-11755828_B953.jpg)

The drive seal wasn’t sitting flat as it should and was leaking at the bottom where it protruded out slightly. Unsure whether it wasn’t lined up correctly when I closed the cases or not but it’s not leaked for the first 50 miles until now. I even put a smear of hondabond on it as recommended in hondamans book so perhaps this held back the oil until now.

Rightly or wrongly I carefully tapped it back in flush and it doesn’t seem to leak any more. Am unable to ride as the seats with the upholsterer but fingers crossed it’s fine

Well, from looking at the picture I would say that either your drive seal is fitted backwards (inside/out) or mine is... I have no leak but perhaps I've just been lucky!
Title: Re: CB750 Barn find project - First Timer
Post by: Underdog1 on August 03, 2019, 11:59:48 PM
Hello chaps.

Well, unfortunately due a new family and other ongoing projects I’ve started thinking about selling the bike. Breaks me a bit knowing that the blood sweat and tears that went into the bike will never truly be reflected in the value.

What do you guys think the bike is worth?

I’ve not been on it for 6 months, there was a problem with the battery not always charging properly, front brake despite having a rebuild isn’t quite right (could just be it needs rebleeeing) and I never truly got the jetting nailed.

Oh and I went abroad for 6 months totally left fuel in it  ;D

Basically I’ve zero time for tinkering so going to shift it instead

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