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SOHC.co.uk Forums => Project Board => Topic started by: SumpMagnet on July 30, 2018, 11:59:58 AM

Title: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on July 30, 2018, 11:59:58 AM
Well...the beast has landed. And what a beast :)

It's a US import, first registered in 1978, but apparantly manufactured in 1977. She came from South Dakota which has hot dry summers and brutal winters, so I reckon this has hibernated for half the year and seen light use for the rest as it's remarkably rust free. I have the US title showing it being sold on to an importer in 2014, and then hung around for a few years before actually getting here. Not sure if that is normal, or if they are stockpiling to drip feed in to keep prices higher. Whatever....she's my bike now!

The seller had put a maroon tank on it to sell it, but that was badly scarred. I asked about the tank ( it had no tap or cap... and I was offered another one if I wanted it ) and both were brought with the bike so I could choose. The other one was black...and apparantly was original to the bike. The same key fits the seat...ignition and petrol cap cover....which is a good sign. Only downer for this tank is the badges have been removed and the gap filled. I hoper they only used filler....not the grinder.... as I want to try and refit the badges. The trusty magnet test revealed no traces of filler anywhere other than the badge recess, and only one small dent in the tank. Wow. Last bike I rebuilt had more filler than tank! Frame rust is minimal and surface only....nothing deep or pitted. No scars or marks on the downtubes. Haven't put the laser on it...but it looks really straight. I genuinely think it's worth what I paid.....which is a good start. Of course...there are probably loads of horrors lurking in there, and I will find out hundreds of things I should have known before buying...but hey. Sometimes...you just have to go for it.

Here's the pretties...

(https://i.imgur.com/YUFOkBo.jpg)

Horrid seat....horrid bars....really not my taste.
(https://i.imgur.com/4DTrOMt.jpg)
(https://i.imgur.com/qJ6oHBw.jpg)

But refreshingly...things like the rear inner mudguard have not been sliced up, the underseat toolbox is still there, and nothing looks too shabby.

(https://i.imgur.com/IO0CNUt.jpg)

Even the engine paint looks passable. Some minor flaking, but really solid in the main and no signs of horrid road rash. One of the points cover bolts is missing.....odds on it is eaither snapped or stripped...but I have had much worse. On runners.

The tank filler neck needs a new seal and a damn good clean....but inside...it's all like this....
(https://i.imgur.com/HLJZAgW.jpg)

Some rust scabbing along the sidestand side edge....but more clean metal than rust. Should clean up a treat, and the seams look in excellent order. I saw how this looked...and chose this one immediately over the maroon one. It even has the sweet little chain to stop you losing the cap. The other one didn't.

The forks look straight and clean...and even the chrome looks OK. A few little pits....but wow. I had a 5 year old Yamaha show worse pitting than this. The chrome on the front mudguard is intact, and looks like it will even shine up nicely. Brakes...don't work...but everything is there. The sludge in the master cylinder probably...er...needs changing...

(https://i.imgur.com/nD2B3t5.jpg)

Stand on the kickstart, and she turns over freely with enough chuff chuff noises and resistance to say it has compression. No nasty clunks, scrapes or scary sounds. Just the noise of air being pumped. Not going to do more until I get a look inside.

Paperwork shows a little over 14,000 miles. Of course....I expect that to be a lie....or short a zero... but looking at this thing, I can actually believe it. I reckon this thing will clean up a treat.

I have a vision in my mind too. Mild cafe racer overhaul, with no cutting/mangling of stock parts. Dropped bars and single seat replacing ones I have to replace anyway. I want shorty 4 intro 4 pipes stopping just short of the wheel spindle, but thast may or may not happen. I am thinking gloss black with a dull silver frame, keeping the black fork lowers and chrome mudguard. Black and silver to offset the black/alloy engine with a few chrome highlights. Black fork gaiters. Fitted chrome ring headl;ight is spotless...so that will stay but on new brackets.

I have a dream.....
Title: Re: CB750F2 .... the project begins!
Post by: Nurse Julie on July 30, 2018, 12:37:52 PM
Great start for a project, it won't be cheap though. Does the front wheel go round, the guard looks very, very close. All rubber bits will be an issue as will be very dry and brittle due to coming from USA, including any rubber bits in the engine. Good luck.
Title: Re: CB750F2 .... the project begins!
Post by: SumpMagnet on July 30, 2018, 12:45:05 PM
She rolls fine, but the front tyre is fossilised.....and the rear is actually worse. Footrest and kickstart rubbers are OK...but they are about the only rubbery bits I trust. Fork seals and dust caps are cracked and dead.

Every hose will get swapped, and if the carb rubbers are dry...they will go too. Expect to replce the o rings on the little round covers on the head.

What other ones should I look out for? Don't really want to put the thing together and find oil pouring out the gearbox output shaft or some such shenanigans.
Title: Re: CB750F2 .... the project begins!
Post by: Nurse Julie on July 30, 2018, 12:50:11 PM
You would need to replace every single rubber part in the engine, O rings, seals, cam tensioner wheels bla bla bla etc. Even in a 40+ year old UK bike they are close to being knackered, if not already so, a USA bike's rubber bits were knacked years ago.
Title: Re: CB750F2 .... the project begins!
Post by: SumpMagnet on July 30, 2018, 12:56:17 PM
LOL....the project list just got longer :)

But if you're gonna do it...do it right. Otherwise....you do it twice...and the second time usually costs more.

I'm just glad to be past the initial turkey purchase fear. That bit where it turns up and you realise you just spent a load of money and bought a rusty pile of doo-doo. I may yet turn out to be wrong, but it genuinely looks OK to me. Wonder what she looks like on the inside......
Title: Re: CB750F2 .... the project begins!
Post by: Nurse Julie on July 30, 2018, 01:03:02 PM
Agree 100% with that statement. Whatever you think you are going to spend on it, double it and add a zero and you will still be underestimating 😀😀😀
Title: Re: CB750F2 .... the project begins!
Post by: SumpMagnet on July 30, 2018, 01:08:37 PM
I'm expecting it to soak up a couple of grand over the rebuild, but I am in no hurry and will buy what I need when I can afford it. At the end, I reckon I will still have spent less than what buying a finished one would cost....I will know what HAS been done....and I will have had the pleasure of doing it.

Title: Re: CB750F2 .... the project begins!
Post by: Nurse Julie on July 30, 2018, 01:12:57 PM
Engine and frame first, everything else just bolts on after that.
Title: Re: CB750F2 .... the project begins!
Post by: UK Pete on July 30, 2018, 01:20:22 PM
Nice project . I also have a couple of F2 projects
Was going to cafe racer them
I can't be arsed now so they will end on eBay probably

Sent from my SM-G930F using Tapatalk

Title: Re: CB750F2 .... the project begins!
Post by: Laverda Dave on July 30, 2018, 02:12:25 PM
Glad to see you have started the rebuild. Keep posting progress photos to keep us all going during the longer winter nights, unless you are planning on completing the build before the end of summer 8).
Title: Re: CB750F2 .... the project begins!
Post by: SumpMagnet on July 30, 2018, 07:23:31 PM
Stripdown Day 1 ..... the good the bad and the ...ugly.

The good first.
Lets be positive. So far there has not been a single stripped thread, sheared bolt or rounded off fastener. The back end is torn down and the rear wheel is out. Tank is off and the wiring all disconnected. The front end is all loosened up, and I just need to block up the front of the engine and drop the front end out. All the pinch bolts bar 1 are loose and everything is set for the last few jobs before I can pull the motor and sort the odds and ends. The bike is not sparkling as it should...so I need to work that out, but I will be doing it without the engine, just earthing the plugs direct to the frame so I can start on the engine once I clear some space in the shed.

The bad.
There was always going to be some, lets face it. It's a 40 year old bike thats been off the road for some time. There has to be a reason...and that's all part of the process. So...what did we find that we did not like today.

1) The exhaust has been off recently. All the nuts were loose, and 2 are missing. As are 3 of the 8 collets. The outside pipes had the 2 they should have. The inner ones had none. That's 4...but I said I had 5...yes. I found one in the little tray next to the battery box under the seat along with the battery strap. Hmmm... my guess....this bike had a good exhaust. Which was sold. A crappy rusted out pipe was then thrown on to sell it with the nuts done up finger tight so the headers felt attached.
2) The speedo drive was not connected at the bottom, and the screw is missing that locates it. The speedo is also quite battered when you look closely with the trip knob bent. The bezel is OK, but the chrome surround is grazed and out of shape. Worst of all...the speedo is blue faced. The tacho is green faced. One of them is not original. Any clues which is which? Can't believe I never spotted that one! Rookie error. No way I believe the stated mileage now. Not that I did anyway, in all honesty, but it was nicce to dream for a while
3) I got an oil leak. Left hand engine case. Left it on the side stand, and it was damp underneath
4) The headlamp is not original. In fact, it looks like it was never actually fitted! The wires and plug were not conected and clearly never had been. None of the clips holding the reflector into the housing were in palce either. All there....just not clipping anything. Judging by the corrosion staining..this was done a while ago, but someone has stuck a headlamp on so it had a headlamp....but never bothered to wire it in or mount it properly. Oh well...
5) Some one has tried to take the ignition switch apart, and the back is held on with a cable tie. Hmmm..oh yes...and the plug fell apart in my hand as I unplugged it. Ho hum. That's life!

The ugly.....
1) Julie was right about the rubber. Tank mounts, rear master cylinder rubbers, fork dust covers and all the little rubber mounts for electrical bits are all rock hard, crusty, or crumbling apart. But I expected it thanks to the advice on here. Still not pretty.
2) Fork seals are perished and oiling up the front, but no surprise there.
3) The seat is horrid, and the base is rusty too. Bin job I think. Not even worth putting on EBay. Sadly, the rear plastic cowl has some damage which will need repairing.
4) The wiring was a shocker. Some very odd bits of 'bridge work'. I started off carefully labelling each connector, but I soon realised this reference work may be wasted as I want to reconnect everything the way the book says....and this sure as hell isn't that!

So, tomorrow..the strip continues, and I can see how straight the frame and front end are. Plus remove the horrid forward pegs someone has added. Still gobsmacked that all the bolts have come undone with no more than WD40 and a ratchet. No breaker bars, lump hammers or swearing. Closest I came to that was the rear wheel spindle. It had corroded on the sprocket side and needed a soak before it shifted. The chain adjuster block that side was grotty too...but the other side is perfect. It should clean up OK.

Here's a bucket load of pics....

(https://i.imgur.com/q3ZiRFc.jpg)

Some bits here to keep...and the tail pipe to scrap
(https://i.imgur.com/Z8SVlGn.jpg)

(https://i.imgur.com/PK2cZv1.jpg)
All the backend, the little toolbox and the worlds ugliest seat. It has a row of rivets for the buttons....bleurgh. I will remove teh plastic cowl, the catch and hinge. The last two will go on whatever seat I do use in the end.

(https://i.imgur.com/sjiNukx.jpg)
Why do I have an exhaust collet under the seat......

(https://i.imgur.com/7IipbpF.jpg)
Swingarm out, and it's grubby in here....but not rusty. Chain is shot...but both sprockets could actually be used....I won't but...well...Worst rust is on the centre stand lower half. It's all solid though and should clean up nicely.

(https://i.imgur.com/0L6v7UN.jpg)
Not so clean under the tank, with a bit of frame rust...but again, nothing deep or serious. Coils have been messed with. One has 'CB750' in marker pen on the side. Replacement from a breakers. Both are marked 'TEK'. The corroded terminals and general state of the wiring probably has a lot to do with the spark issues.

(https://i.imgur.com/Y7HzyYf.jpg)
Those are genuine FVQ shocks. They probably stil do fade very quickly....but they don't leak. They have bugger all damping, so probably don't leak due to having no oil.....

(https://i.imgur.com/jJM4OuM.jpg)
Who did this....why did they do it....can I have them shot please.

(https://i.imgur.com/vY1IA7w.jpg)
It's shiny...it's never been properly fitted. I might actually use it. The rubber boot over the bulb hole is also perished.

(https://i.imgur.com/HtoawDl.jpg)
So here's where we stopped. A mixed bag of stuff, but impressed with the build quality. Nervous about what I will find lurking in the engine, but also prepared for that to swallow the bulk of the budget. If I get off lightly there...that leaves more for nice pipes and professional paint. I also got a real reminder of how things have changed when I picked up the rear wheel and nearly ruptured a disc. Do they use air or lead to fill the tyres?

Title: Re: CB750F2 .... the project begins!
Post by: Green1 on July 30, 2018, 07:46:24 PM
People do like to butcher the wiring for some reason. I'm still cutting those horrid red bullets out of mine.
And after stripping all that weight its still bloody heavy 
   
Title: Re: CB750F2 .... the project begins!
Post by: SteveD CB500K0 on July 30, 2018, 08:52:56 PM
I like your style. There’s not much like a pragmatic and honest approach.

At some stage you will probably want to change the name of this thread… if you edit the first (original) post title, all subsequent replies will use that text.

Steve


Sent from my iPhone using Tapatalk
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on July 30, 2018, 09:27:22 PM
Thanks Steve :) I just did that.

I've done a few bike rebuilds in my time, but this is new territory in terms of scope and complexity. I also have a very good idea what can happen....will happen....must not happen with a project. Wish I had internet and forums for some of them! The amount of know how out there that I can tap into makes things a lot easier.

But I learnt the hard way how many nasties can lurk. A supposedly low mileage Guzzi LeMans with a clutch plate that had sheared rivets. Was fine until one landed in between the plates. Or a Kawasaki with a frame scarred on the downtube with a big gouge full of filler. That one pulled left really badly.....or a Z650 with an ovalled out headstock and an upper bearing race fixed wioth chemical metal.

The stripdown on this bike has been a breeze really. Bolts are coming undone without drilling, swearing and screaming. Nothing so far has snapped, rounded or come off in my hand. Some bits of it look REALLY clean...like the carbs. Other bits will need refinishing. Like the frame, swingarm etc. But the elephant in the room is the engine....

My parts list is growing already, but I am hooked. And so far....every part I cannot save/use is one I would have replaced anyway....and that makes me feel good. I hate ruining a classic, but changing seats, bars etc. that are not original and not usable is no crime. My rule here, though, is that I will do nothing that cannot be undone if the bike were ever to be put back to stock.

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Nurse Julie on July 30, 2018, 10:23:52 PM
Will you be able to get the finished beauty out of the shed and through the house complete, or will it go back together on the front path?
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on July 30, 2018, 10:59:32 PM
It's a multi stage task....

1) strip and carry through the house to the shed to work on main assemblies.

2) dry build in back garden where it's safe

3) when it's all snag free...break it down for final assembly out front.

I want to be able to work in a safe place e where I can stop for a break and not need to pack everything away. Nasty right turn off the hall prevents a clear run with a complete bike...and not getting a divorce prevents me building it in the hallway 🤔
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: MCTID on July 31, 2018, 08:27:03 AM
My Brother in Law built a 26 foot long steel boat in his back garden, then when it was finished he lifted it up and over his Bungalow with a Crane.................just saying.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on July 31, 2018, 08:34:32 AM
I like your thinking....

Or I could try this..
https://www.google.co.uk/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3Ds3wPYqQYSNA&ved=2ahUKEwiDwI606cjcAhWIAMAKHbfOAL4QtwIwAXoECAMQAQ&usg=AOvVaw3xR3IeoFPRjwgv3k7jEd9z
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: paul G on July 31, 2018, 08:45:00 AM
I like your thinking....

Or I could try this..
https://www.google.co.uk/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3Ds3wPYqQYSNA&ved=2ahUKEwiDwI606cjcAhWIAMAKHbfOAL4QtwIwAXoECAMQAQ&usg=AOvVaw3xR3IeoFPRjwgv3k7jEd9z

 ;D ;D ;D think I would go for the dry build though ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Moorey on July 31, 2018, 08:52:20 AM
Leave the complete front end off, remove the rear wheel and stand it up on the swing arm ends on a sack cart or dolly and a couple of you should be able to get it through the house. I've done it many moons ago. But you have plenty off time to think about that one yet.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: royhall on July 31, 2018, 09:17:48 AM
Hi. Are you selling off the bits you don't want to help fund it. If you are can I have first dibs on the exhaust headers. I fully restored one of these a few years ago and at 14000  miles the head will be ready for a rebuild, specifically the exhaust valve guides. Sorry to sound mercenary about the exhaust but you have to get in quick on here. Good luck with the build.

Sent from my Nexus 6 using Tapatalk

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on July 31, 2018, 12:46:01 PM
Looks like that will keep you off the streets for quite some time, it's good that you are taking lots of photos, I found it handy when reassembling, especially for cable and wiring runs.

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on July 31, 2018, 01:02:02 PM
With front and back ends off, we just about managed. Made a harness for the front to take the weight, with second person steering from the frame rails at the back. Damned heavy.. my back is aching...but we did it. These things are VERY heavy. Will get a sack truck for next time.

Next job is to get the engine out. I have made a cradle out of scrap wood so I can roll the frame over...and lift it off. Then I have a stretcher frame to move the engine so I can get it in the shed and on the bench. Once I have recovered..

As far as mileage goes...I am pretty sure the Speedo is not original, so I am assuming high mileage...and expecting at least a tip end overhaul. Plus..can gain tensioner, guides etc.

Better that way I think. Pessimists only get nice surprises. Optimists set themselves up for disappointment......

Nice surprise 1...
The forks dropped out if the yokes nice and clean, with no suspicious tight spots. A sign of straightness. Chrome is amazingly good. I have got bikes through MOTs with worse. 

Nice surprise 2..
The headstock was nice and tidy with no I ovalling, and the bearings had been greased. And the castle but had never seen a hammer and screwdriver.   

Today's odd find.   
Something looked to have been welded on the frame behind the tank mounts at some point, either side of the centre top tube. Then removed and painted over. Thought it was damage until I realised it was on both sides and symmetrical. Wonder what was there... 

Now...my surplus parts...
I probably will be selling on the bits I don't need to help buy the bits I do. Not immediately, just in case plans change...but as soon as I have a replacement part paid for. But drop me a message on the headers and I will give you first refusal when  I sell. Going to cut off the remnant of tail pipe as the clamp is messed up and give the chrome a clean so I can check condition.

Not sure yet on the headlamp brackets. The clamps on the ones I have are good...and I have some scrap 4mm ally plate (6061 I think) so might make my own. Depends if I can find an original headlamp assembly.

This afternoon's job is to make a bearing retainer tool ....
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Nurse Julie on July 31, 2018, 01:09:50 PM
Going great guns, well done. False economy and bad practice just hoping to do a top end rebuild. There are rubber seals and O rings that will be perished in the bottom end and it is a bit fool hardy not changing the primary chains whilst the engine is out. You could start it up after a top end overhaul and the bottom end could most probably be clanking away (more than they do at the best of times) and you would need to take engine out again.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on July 31, 2018, 02:55:46 PM
Good point and noted about the primary chain and tensioner. I'm more used to Hy-Vo types that last forever, and this is a roller one. Added to the list of things.

So it's strip down the top and both sides, flip it over and split the cases. Check gearbox bearings, shafts, gears, selectors. Check the state of the crank, replace the primary chain and tensioner, sort the camchain and tensioner/guides. Gearbox output bearing and seal will probably get swapped as well. Exhaust valve guides, find at least 3 more exhaust collets, add in a full gasket set....and replace anything worn out or broken. Which will probably include me by then :)

meanwhile....the shelving set aside for bits in the shed is filling up nicely...
(https://i.imgur.com/iIQvBmp.jpg)

All the smaller bits are labelled, fasteners replaced in situ, and boxed or bagged up
(https://i.imgur.com/z9GcCcc.jpg)

The frame and engine are in the back garden safely wrapped up while I tidy up and get ready for the next stage. I even had time to relax and experience the joys of the laid back easy rider bars this thing arrived with.....
(https://i.imgur.com/Ae2AM8N.jpg)

you didn't think I was going to put  them on a bike!!!

While I try to figure out what might have been attached here....
(https://i.imgur.com/szH25D3.jpg)
Weld scar on the first layer of bracing....at the corner of the second. There is an identical one on the other side.

I also need to work out how to strip and paint the frame without losing the rivetted on ID plate. Sure, there is a seperate stamped number, but I would really like to retain it.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Nurse Julie on July 31, 2018, 03:06:47 PM
The frame looks standard to me, no extra bits and no bits missing either.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on July 31, 2018, 03:08:51 PM
The weld scar is just a weld through point to the underlying tube of main frame. 

It's to raise the torsional rigidity of that top tube going into the headstock or else the pressing could to rotate around the tube. Also distributes the weld loading further along the tube from that seam weld to assist in avoiding a stress fracture at the seam point.

They'd have had two holes there in production so that they can build weld up on the base tube within the hole and then fix it to the perimeter of the outer pressing.

I think.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on July 31, 2018, 03:48:40 PM
Thanks ...you lot know EVERYTHING!

Nice to know this sort of thing, as I want to learn all I can about the beast as I go, good and bad, and ugly. I would be tempted to break out hte grinding pad and remove it...but now I won't. It's supposed to be there....so there it will stay :)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Bryanj on July 31, 2018, 04:04:47 PM
Gearbox bearings rarely need replacing unless allowed to go rusty and several are Honda only (expensive) due to grooves on the outer, rest is just time, care and super cleanliness
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: petermigreen on July 31, 2018, 06:53:50 PM

I also need to work out how to strip and paint the frame without losing the rivetted on ID plate. Sure, there is a seperate stamped number, but I would really like to retain it.
There are two ways to retain the vin plate. You could mask it off or ask your powder coater/painter to mask it off but mine won't do it.

or you can carefully remove the rivets and replace the plate after painting. I used these

https://www.oneillvintageford.co.uk/cgi-bin/sh000001.cgi?REFPAGE=https%3a%2f%2fwww%2eoneillvintageford%2eco%2euk%2f&WD=rivet&PN=Ford_Model_A_Dash_Plates%2ehtml%23a_23100#a_23100

[attach=1]

Probably available elsewhere also but haven't been able to find them.

Select suitable size rivets from the pack and measure diameter then find a drill bit a shade smaller and they tap in quite easily.

BUT.
If you need to get registered in the UK make sure you take a photo of the vin plate BEFORE you remove it for evidence. I nearly came unstuck with my CB400F restoration because the dating officer said it showed evidence of tampering which technically it had as I'd removed it and replaced it but on the same bike so no shenanigans  ;D
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on July 31, 2018, 07:36:54 PM
I'm my own painter....so I will try masking it off.

If that fails...I will follow your advice, remove it and re-rivet...but photgraph it first. I have the US title paperwork with the details on confirming year of reg etc. plus VIN/Engine numbers...so I will hold that up in the photo too. That's a handy thing to know. Easy pitfall to avoid.....but only when you know!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Moorey on July 31, 2018, 08:21:21 PM
If your HT leads look a bit grim do not bin them. Click on Alladins Cave and read Ash's coil fix.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 01, 2018, 11:26:21 AM
The leads are rock hard...and I am on the 'how to swap your leads' article like a tramp on chips.

No point troubleshooting ignition faults with corroded caps and crusty leads....and I don't want to buy pattern coils if my originals are still good.

First job on the electrical side is to stick a 12v DC supply on the battery end....and see what comes through. If anything!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Rob62 on August 01, 2018, 12:53:57 PM
I also had problems with my 44 year old leads, they looked ok and weren't hard, but once the motor fired up and warmed up, the centre insulation started to melt and the suppressor caps fell off!. I think the coil repair idea is cool and definitely one for the concourse restoration. But if you want a trouble free cheap solution the wemoto coils are ok.. £25 each and even though they are cheap they have to be better performance than the 1960's / 1970's ones they are replacing. You cant see them on the bike (although they look ok anyway) and the motor runs beautifully. The other option is to go electronic and ditch the whole system, coils, points, condensers etc... I may go down that route eventually. but for now the wemoto coils are a cheap easy solution. As always, its a matter of personal choice.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 01, 2018, 08:50:22 PM
Now at crunch point.....it's time to take the engine out of the frame. My strained muscles ahve recovered enough after I dragged it through the house with the aid of my eldest lad. Damn...it weighs a TON!!!!

Now...I have knocked up a little wooden frame which will fit around the points cover. It's not a wonderful points cover....and a bit crinkled....but that's not the point. I don't want to grind it into the floor. My plan is to roll the bike over onto this little frame. Then I can lift the frame and bits off the engine....Then the engine can be carried to the shed and rolled back the right way up on the workmate. Then I can start the top end strip in slow time.

For some reason...I am not 100% sold on just lifting the engine out sideways. Clearance is not good...and the lump is ...er...a lump!

If this goes well...I shall use the same method to put a hiny rebuilt engine into a shiny freshly painted frame. Should result in a whole lot less scraped things. If there is a better way...well...please tell me know! This shall be done by the weekend.

Meanwhile...I will be trying to sort the wiring and electrics, which I have left on the frame for now. Makes it easier to work with as I do not plan on using engine power here. Points will be 'simulated' with a push to break switch so I can energise the coils and break the circuit to cehck for sparks. Should all go well :)

Then..well...then I need to start drawing up a list of what parts just need a refurb, what just needs a cleanup...list what I know I need to buy and start pricing up the things.I need to spend a few days thinking....doodling...planning...and deciding. I have an outline vision of what I want to do....and now is the time to turn the outline into a much more concrete plan.

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Nurse Julie on August 01, 2018, 09:16:20 PM
If you need a proper engine stand, we make them and sell them to forum members. They give enough clearance that you can build the complete engine, including sump. PM me if you ever need one, no complaints from forum members so far who are or have used them. Check the max weight if the work mate, you need about 100kg. I help Graham lift these engines and I'm no wimp but they are bloody, bloody heavy, especially lifting from floor to strip down bench so just be careful.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 02, 2018, 07:41:45 AM
The workmate is ok for the weight, but I hear you on just how heavy these things are. We barely managed to shift the lump in the frame, so was guessing around the 100kg mark for the engine. Hence my desire to avoid trying to dead lift it out if the frame.

Engine stand interests me. Any chance you could message me some details/pics/prices? May have to save up the pennies, but these sorts of things often repay in ease of working, lack of scraped knuckles and avoided aggravation further down the line.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Nurse Julie on August 02, 2018, 08:09:20 AM
PM me your email address and I will send you some pics etc later. Off out for a ride now, it's such a glorious morning.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on August 02, 2018, 09:32:18 AM
For just generally laying them on their side to remove engine or just sitting around and to avoid find/casing damage, you can use an old car tire.
They'll usually let you have one for nowt at a friendly tire depot,  14 Inch diameter is not a bad size for it.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: UK Pete on August 02, 2018, 09:57:38 AM
What a good idea nigel
For just generally laying them on their side to remove engine or just sitting around and to avoid find/casing damage, you can use an old car tire.
They'll usually let you have one for nowt at a friendly tire depot,  14 Inch diameter is not a bad size for it.

Sent from my SM-G930F using Tapatalk

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 02, 2018, 11:44:26 AM
Car tyre.....DOH.

Bloody obvious really. Annoyingly...the wife just had 2 new tyres on the car, and I could have had one of those while it was being done...but I have a tyre place just round the corner. Guess whereI am off to next :)

But we got some more stripdown work done today. Found things....learnt things....discovered my knees have more  wear then an old set of exhaust valve guides. Sadly...I cannot find replacements on E-Bay so will have to just spray with WD40 and give them a wire brush. Worked for most other parts.

Got a pile of odds and ends off, and discoverd my brake pedal is bent and was fouling the footrest. Will ease this into shape. Otherwise...it's perfectly usable for now. Onto my second box of 'bits' all labelled, itemised, and itinerised. Is that a word? I will not be rummaging for lost bits when I put it back together....... ( OK ... I know I will....and will be reminded of my rash statement... )
(https://i.imgur.com/5Id2KEM.jpg)

Carbs are off....levered from the iron hard grip of the carb 'rubbers' ..... Might need new ones here....or a sledge hammer to repalce the carbs. Slides look pristine...but any wear will be in the body not the slide, as chrome is harder than alloy, but I dreaded rust spots on the slides. Found some fuel residue in the bowls. Was liquid.....but fuel is probably giving it more credit than it deserves. But rather that than bone dry and dusty.
(https://i.imgur.com/HH9IlXS.jpg)

Now...as with all strip down sessions...there were things found I didn't like.

1) The rear upper engine bolt is the wrong size. Too narrow by a few mm. Don;t like that. I thought the bolt was bent...but no. It was just skewed in the frame. All the other bolts are OK and all the mounts line up nicely, so I reckon someone wrecked the thread 'removing' it with a hammer at some point. This was not a recent bodge, as the thing was quite corroded along the groove it sits in. Have noted that for replacement.
(https://i.imgur.com/CoeKqjy.jpg)

2) One of the points cover screws has been helicoiled. The bottom screw was missing...but thankfully the thread isn't! Also the cases underneath are not damaged. The end cover is battered, but the alloy under is unmarked. I suspect a swapover.....

I also learnt some lessons.....

1) The rear oil pipe is the feed pipe. This is the one that will still be full of oil when you drain the tank, and whilst it does not hold much oil, it is enough when you are trying to block it off and keep oil off the patio at the same time. This brings me onto lesson 2...

2) I found out the use for the plastic trasy under the seat. The one next to the battery holder. It's purpose is to ensure you cannot get the oil tank out of the frame while trying to move the gunk coated oil pipes out without dropping more oil on the floor. Yes. Who says the Japanese have no sense of humour. It is the perfect depth to prevent the tank coming out.

And I have one of those 'what is this thing' issues to resolve.

Whilst prepping for engine out, I have removed the breather pipe from the back of the gearbox that goes to the oil tank. I also have another pipe going from the cam cover down to a small round catch tank under the battery tray. This had another pipe running to...well..I don't know because it was not attached when I got the bike, but I suspect the airbox...and a drain pipe that weaves it's way down to behind the right hand footrest hanger. Presumably it's a catch tank for a cambox breather, recycling into the airbox to burn off residue in the engine, and an overflow pipe for emergency and to prevent airlocking. Is this a standard fitment for all ...or is this a US emissions thing? I would expect the crankcase breather....but not sure about the other.

I also....thankfully...found the most useful of tools. It was also the first EVER special tool I bought. 32 years ago. From a Honda dealer in Yeovil, Somerset. I had a CB125T2, and was struggling to undo the cross head screws on the sprocket cover to fit a new chain. Asked for advice...and was told to buy a particular t-bar screwdriver....which they happened to have. 32 years later...I am still using it, and it is still a perfect size and fit for 70's Honda screws in engine casings. Fits snug, gives good purchase, and lets you put enough weight on while you turn it.
(https://i.imgur.com/EfaytlX.jpg)

Thank you Paul Branson's of Yeovil. ( I think they are still going as well )

But with all the engine mounting bolts loosened off, and lightly nipped back up ( so I know they will all budge with minimal effort ) , the wiring off, the oil pipes off, and everything likely to get in the way removed....I was beaten by the heat. Tomorrow.....the engine leaves the frame :)

edit: Forgot to say...I found the cover from between the horns jammed into the toolbox under the seat... and...one lug from the left hand sidepanel. It was missing when I got the bike..but guess what...I have one mounting lug! It was wedged in the rubber.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on August 02, 2018, 12:30:51 PM
Breather cover and oil filter housing off makes it easier  ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: paul G on August 02, 2018, 12:38:00 PM
Interesting writeup sumpmagnet :) keep up the good work.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: UK Pete on August 02, 2018, 12:38:41 PM
And exhaust studs
Breather cover and oil filter housing off makes it easier  ;)

Sent from my SM-G930F using Tapatalk

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: AshimotoK0 on August 02, 2018, 12:46:04 PM
Man that Vessel JIS T driver takes me back  .. our local 5-star Honda dealer sold me mine in 1971 (Peters of Hull) Excellent bit of kit.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on August 02, 2018, 01:44:15 PM
Here's a diagram of the breather system.
(https://imageshack.com/a/img921/2658/zKGqKT.jpg)

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on August 02, 2018, 01:54:43 PM
Found more
(https://imageshack.com/a/img921/3672/gbzKC2.jpg)
(https://imageshack.com/a/img923/1295/CvA56H.jpg)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on August 02, 2018, 02:13:09 PM
Just for inspiration, I also found out that my knees and other bodily parts do not work as they used to so when lumping around the engine on mine I had to ask the grandson for help and be creative. So with a nicely finished engine and frame I gave him the call and we fitted the frame to the engine, using some blocks of wood, bricks and some carpet.
(https://imageshack.com/a/img922/4370/Z0OUVg.jpg)
(https://imageshack.com/a/img923/8387/Nt9bH6.jpg)
(https://imageshack.com/a/img921/346/iXcvie.jpg)
(https://imageshack.com/a/img921/1958/yqyDBU.jpg)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 02, 2018, 04:08:48 PM
I already got the oil filter housing loosened...was worried the bolt might be siezed....but it shifted no bother.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 03, 2018, 08:03:16 AM
Spitfire..that is brilliant info. Many thanks.

And I hope my motor looks as tidy when I put it back in!

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 03, 2018, 02:04:29 PM
Bugger...   

Minor slip lifting the frame, after I forgot the breather cover.. and stopped to remove it. Damn thing settled and nipped my hand between head and frame. Inch long gouge in hand and claret all over the shop. Joy.

Off to casualty and a few days delay finishing the job.

Damn...damn....damn and bother.

Still..on the plus side, all the engine bolts came out sweet and there are no cracks, chunks or nasties on the cases I can see. There are some dog eared screws on the end cases, and I know they are not coming out without a fight. The X is already an O..   

Had an oil leak from under the generator cover, so that will need looking at. Not sure there should evenbe oil there....

So. 

1) get stitched up
2) clean up the message I made
3) work out how to do this job with one less hand....
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: hairygit on August 03, 2018, 02:38:10 PM
The CB750 alternator runs in oil, so there should be oil in there.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 03, 2018, 05:23:05 PM
Ok...that's a relief :)

I think someone tried to get in there before, butchered the screws trying to get the end cover off...then just took the whole thing off and refitted with the old gasket. It looked all fine diwn there, but was leaking badly. Once i get around to it....I will clean all the muck away and have a proper look and check for signs of damage.

Meantime...doctors orders say no lifting/heavy work for at least a week...then it's back to getting the frame off then engine. Breaks my heart seeing her lying on her side out the back...and me unable to help. Still...the motor is supported on wooden blocks and I have wedged the frame too, so the end cases are nowhere near the deck, and the load is on the block/barrel and engine mounts.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Moorey on August 03, 2018, 07:42:41 PM
Man that Vessel JIS T driver takes me back  .. our local 5-star Honda dealer sold me mine in 1971 (Peters of Hull) Excellent bit of kit.

I wish you could still get them. I could do with some new ones.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Rob62 on August 03, 2018, 07:54:08 PM
Wow that engine looks beautiful! Great paint job!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Green1 on August 03, 2018, 08:12:34 PM
Man that Vessel JIS T driver takes me back  .. our local 5-star Honda dealer sold me mine in 1971 (Peters of Hull) Excellent bit of kit.

I wish you could still get them. I could do with some new ones.

I have one its been bent and the plastic hand grip is missing but its still the go too screwdriver because it works.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Bryanj on August 04, 2018, 10:03:16 AM
You can get them as a Honda part number but sit down before you order!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: philward on August 04, 2018, 01:49:37 PM
Found more
(https://imageshack.com/a/img921/3672/gbzKC2.jpg)
(https://imageshack.com/a/img923/1295/CvA56H.jpg)
Sorry to high jack the thread but been following the thread and in the diagramme I noticed the 'breather separator' and this may be an answer to my need for a oil tank catch tank if I modify it (I'm struggling for space under the hump where the tank normally goes as I have put a battery there).
Can anybody give me some dimensions for this part please - part number 17360405000
Thanks guys
Phil
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on August 04, 2018, 02:06:59 PM
I am not sure why you need a catch tank ? If the breather pipe comes off the breather cover, them just do a pipe like on the K6  ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: philward on August 04, 2018, 04:37:29 PM
There's an overflow that goes back to they rear crankcase but 2 more rear facing overflow pipes that exit right over the rear wheel - don't fancy just pipes!

Sent from my Moto G (5) using Tapatalk

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 04, 2018, 08:07:04 PM
@Philward
I will nip out tomorrow and measure the seperator on mine for you.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: philward on August 04, 2018, 08:42:13 PM
Thanks
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 06, 2018, 02:31:33 PM
After slicing a chunk out of my hand, I have been out of action for the last few days and unable to do a lot.

The engine is still stranded in the frame like a beached whale, and there isn't much I can do about it for a few more days...so I have started turning to some of the smaller jobs that I can do.
Largely cleaning up, and assessing condition for some of hte other parts.

It does raised a big question as to the value of retaining some of the US spec parts and dubious add ons. Do they have any value at all?

High bars. Horrid shape, and so pulled back your wrists are 90 degrees from where nature says they are comfortable?
That seat....just look at it in the first few pics. The base is corroded down one side underneath, with a few areas thin enough to poke a stick through. I could pull off the cover and the foam and have a go at welding in some fresh sheet metal to rebuild it, but I can't see myself ever having a need for it in the shape it is. I mean..it has buttons down the middle for gods sake. Rivets in the pan hold the strings that keep the buttons in. If I want a stock seat, it is probably cheaper to buy a replacement than have this retrimmed with new foam and vinyl. Not to mention the time and effort to remove the rot.
The exhaust is proving a stubborn beast too. The stub of the rotted end pipe is resisting my efforts to remove it, and there looks to have been some loss of metal around the end of the header where it goes into the end pipe. It's just a pile of rust. I had to Dremel the bracket to remove it....and am now slicing metal again to get rid of the last bit. I am afraid it might not be worth it when I do get it off. But ...we got to try!

The 'cruiser pegs' on the front engine mounts are being used to ballast my bike cover and stop the wind blowing it off. Probably the most useful role they will ever perform. Another piece of metal I can't find the enthusiasm to E-Bay and will never have on any bike of mine.

So...what have we done:

Straightened the rear brake lever.
Stripped and cleaned up the seat hinge/catch
Removed the rear cowl from the seat and started a bit of patching work
Cleaned a few shiny bits
Started removing hte bearing races from the steering stem.

Not what I want to be doing...but small steps will have to do until I can do the bit bits again
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: paul G on August 06, 2018, 02:41:35 PM
Still got your sense of humour ;) keep up the good work as you say small steps until you can get back into it.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on August 07, 2018, 07:19:44 PM
Was tidying my shelves today and found the vent trap from the F2 here's what it looks like.
(https://imageshack.com/a/img923/8817/pfRuWn.jpg)
(https://imageshack.com/a/img922/3796/GFPVjb.jpg)

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: philward on August 07, 2018, 08:31:58 PM
Dennis, is the vent trap surplus - if so let me know what you want for it
Phil
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on August 08, 2018, 11:02:21 AM
Sorry Phil it's probably the only part of an F2 that I have only one of.

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: philward on August 08, 2018, 11:10:19 AM
Thanks anyway Dennis

Sent from my Moto G (5) using Tapatalk

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 10, 2018, 01:28:08 PM
It's a funny old world.......

My last attempt at removing the engine had resulted in a weeks downtime on the project, a trip to casualty, and a fair bit of discomfort. But then things began to look up.

My hand was on the mend and whilst it still aches, had knitted together well enough for me to leave the dressings off and for it to start doing some work. Even better...another member on here, petermigreen, had offered to pop down and give me a hand...sorry.....couldn't help that one.... He had a couple of days off, and was looking for an excuse to enjoy the sunshine on his bike.

Only....the weather gods had another idea. After 3 months of drought, sun, scorching temperatures and rainfall that would not look out of place in the sahara....on the day we had chosen ( both of us off work... ) the heavens opened. It sluiced it down all day. No worries....reset, and go for Friday. Nope. The monsoon has carried on. I had a couple of hours this morning when it was still OK with the rain due around lunchtime.

So....I pulled the exhaust studs, undid 2 of the screws on the head breather cover....and applied the impact driver to the single screw that was already a bit chewed, and refused to shift despite an overnight soak with WD40. With the immortal good luck chant of 'shiftyabugger' upon my lips, it too gave up and undid. With the judicious use of a pair of axle stands, a trolley jack, and some zen buddhist meditation of teh miracles of geometry.....the end result was this....

(https://i.imgur.com/h0LmWa9.jpg)

and this....

(https://i.imgur.com/lfjJ9Pa.jpg)

The engine, of course, immediately tried to fall over, but with the aid of my youngest lad ( I say youngest...he's 18 and about a foot taller than me... ) the engine was rolled back the right way up. Straps went under the front, and onto the rear upper mounting bolt....and we manhandled ( man and boyhandled ??? ) the lump down the garden to the shed, in much the same way as our primitive ancesters shifted the rocks to make stonehenge.....

With that in the shed, we sacrificed a goat, and feasted ( well...no...I put the kettle on....)

The engine is in the shed....the frame is in the shed. The engine is sitting on a wooden cradle on the floor, as we simply could not get it up onto the bench with comfort....but it is where I can work on it. 5 minutes later......the heavens opened.

Thank you weather gods.

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: petermigreen on August 10, 2018, 01:38:13 PM
Yay, what a result.
All you've got to worry about now is getting it back in the frame without scratching all the new paint.  :o
Peter
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 10, 2018, 02:37:51 PM
maybe I could cut the frame in half...lift it over...and weld it back..... just a bit of touching up needed then.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on August 10, 2018, 06:18:42 PM
Now the fun begins !

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 12, 2018, 05:59:56 PM
Today the fun does indeed begin.....after a break yesterday for a flight in a Tiger Moth...and the chance to stand next to a Spitfire.....

So today, I started to delve into the top end of the engine.

Turning the motor over on the crank end nut did not feel brilliant in terms of compression. So....it might be the rings, or it might be the bores. Will find out.

Got the cam cover off with not too much bother, and only one screw head showed previous damage, and needed the impact driver. All the others released nicely. The two bolts under the breather cover were unmarked and perfect...so I wonder if anyone had ever undone those before. The others someone had tried to undo...
Under the cover, things were better than I was fearing. I always expect the worst when opening up something like this. It's like a Christmas present from an elderly relative. You have no idea what is going to be in there....but it's usually a disappointment. Rarely do you find what you hope for under the wrapping.

thankfully....this was not bad at all.

(https://i.imgur.com/Zlm0CNa.jpg)

First plus point was the cleaar evidence of old oil residue over everything. I had feared dry....rusty cams. What I can see of the cams looks nice and shiny, with no evidence of scoring or wear marks. I have seen much worse.....including a set of Z650 cams that looked like a ploughed field.... 'was a good runner' according to the seller. He was an idiot...according to the buyer. The camchain still has good tension, and was oily...so there has been oil around these here parts.....

Worryingly....it has a full set of brand new plugs. Not a hint of carbon on them. I suspect someone was trying to get this thing to start, and found the electrical issues I was told about. They gave up clearly.

(https://i.imgur.com/Zb06wum.jpg)

On the plus side....there was no evidence on any of the head bolts, cam bolts or cam carrier bolts to show someone had tried to undo any of them. That is reassuring...as it means I am not going to find someone elses foul up lurkling in here. Just wear and tear. Please go easy on the tear...

I have popped a slug of oil down eacy barrel and given it a few cranks by hand....then ligtly dropped hte plugs back in to keep the spiders out. That can sit over night to seep down the rings and coat the bores a bit. I also need to read up the manual a bit for the correct dismantling sequence. If there is a correct sequence for torquing down bolts..... I want to undo them in the reverse order. It may not be necessary...but I reckon it to be good practice. Plus I want to get an idea of how it all should fit together before I take it apart.....

tomorrow....I have an appointment with the Spanish Inquisitions chief torturer....sorry....the Dental Hygenist....so a bit of light reading will take my mind off the horrors to come
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on August 12, 2018, 06:08:36 PM
That looks nice and clean inside, not even any burnt oil staining to the cam towers  :o
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: petermigreen on August 12, 2018, 08:01:17 PM
Looks like a promising start John. Happy for you. At this stage I’d put the lid back on and leave it alone.
Welcome to my world of pain, I’m married to a Dental Hygienist!


Sent from my iPhone using Tapatalk
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 12, 2018, 09:17:55 PM
Close it up and leave it alone...what!!....and miss out on the joy of finding out the piston rings are all missing.... no.....we must go deeper!

Next stop, the oil jets. Then the head needs to come off. I don't have a compression tester, but I don't think there is enough. Could just be a sticky ring or two, but I want to check the bores for wear, and replace the camchain guides and such.

But, seriously, I was pleased with what I saw when I lifted the cam cover. It looked clean, with just a sheen of oil and little puddles of the black stuff on the valve springs, and in the little recesses around the head. Indicates I have had oil flow there last time the engine ran, and that the parts were still coated with enough oil to keep corrosion away. ivesd me reason to hope the plain bearing surfaces on cams and crank will look OK. But....not going to get too optimistic.

I have honestly got no idea what the mileage is on this motor, as the speedo reading of 14K cannot be relied on, as the speedo is blue faced.....and the tacho green faced. I think they should both be green....which means the speedo is a replacement. Also...the chrome surround on the speedo is bent and a bit battered....so it's had a fall that would have taken out the speedo....and another put in it's place.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on August 13, 2018, 11:04:39 AM
Pretty sure that both the speedo and rev counter on mine are both blue faced.

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 13, 2018, 11:57:24 AM
So a blue faced speedo is a good sign...and a green faced one bad... I'll double check what I have.

But, as there was utter rubbish on the TV last night, after feeding my face, I sloped off to the shed again for a bit more on the engine. Now have it stripped down to the head, and the dreaded ....oil jets. I am also at the point where I really need some expert advice.

Here's todays update on the tale of my hefty motor.

When I last looked, the cam cover was off, and I was greeted by a pleasantly oily sight. This was good, as it implied there was oil up here....but as I do not intend on doing the motor hokey-cokey...when it goes in...it's staying in! So I needed to check further down.

The motor felt a bit better on compression for an overnight oil soak, but that joy still awaits...

All came apart nice and easy, aside from one of the outer cam cap bolts. It felt a bit stiff when I undid it. No sign of alloy pickup on the thread, but it is something I will want to have a look at before it all goes together. I read the instructions about the cam position....and set it carefully...before realising I had to remove the rocker shafts first, as even with the tappet adjusters loosened, the cam was under load from at least one point at all times. So...out with the rockers, taking great care to position everything so the same bits go where they came from when I rebuild. All 4 slid out smoothly and looked oily and smooth.

(https://i.imgur.com/FVSNzfW.jpg)

I can see the wear patch where it contacts the cam, but they all look pretty even and there is no sign of scoring or damage. Hopefully it means either the previous owners actually adjusted the valve clearances...or else it never needed it.....yeah....right.

Removed the camchain tensioner once I had the cam aligned as per the book....line horizontal...cutout to the top....OK...now I can't get a socket on the cam gear bolts. Found a spanner I could fit in, and undid them. The book says.. 'the lower screw will just clear the head'. It does. What it doesn't say is that it's only about 10mm long and if it slips, it's going right down the cmachain tunnel. In goes the emergency 'save' rag but the bolt was removed without drama. Why.....for the love of god...not have the bolts on a horizontal plane where both were easy to get at? Oh well...

With the camchain cable tied to a point of safety, out came the cam. Wiggled off the cam gear and manouvered out of the way.

(https://i.imgur.com/gW5l8qe.jpg)

Cam gear and bolts were stuck back together loosely, so I don't lose them. Always put the bolt back in the 'ole...I was told as a lad. Then you know where it goes.

My motor now looks like this. I noticed a distinctive scratch on the paint UNDER one of the carriers. Wasn't me....wonder how that got there....Had me checking for screwdriver marks all around the cam carriers in case someone thought that was the correct way to shift well settled parts. A few gentle taps with the palm of the hand, and a wiggle or two...and up they came for me.

(https://i.imgur.com/NPBwVJg.jpg)

I will have to clean out hte plug recesses...as the newly revealed holes in the casting had cobwebs in them.....Plugs back in....followed by a clean and a blast with the air line methinks.

Now for the questions....

On the motor...everything is labelled left/right based on the engine in the frame and the riders view when sat on board. I thought. Is this right? The cam was that way round...when viewed from the front the 'R' was to the left. On the cam carriers, I had the right side labelled '30' in small engraved numbers and the left '25'. Each of the cam caps was also labelled 25 and 30 respectively with either an R or an L....but as I looked from the front....the L's were to my left....or the bikes right? Has someone swapped them round....and should I leave them or swap them back?

Secondly....while the caps were perfect with just some signs of overall buffing ( matt looking rather than shiny )

(https://i.imgur.com/HsqUz0R.jpg)

I could see some signs of scoring on the lower sections. Is this too bad to use? Can it be sorted? Are replacements as hard to find as they seem? I looked at a few used sets on E-Bay and they made mine look like new....

(https://i.imgur.com/Mhlb4xM.jpg)

(https://i.imgur.com/V89Vi5o.jpg)

Last, in my barrage of questions is the oil jets. The picture shows the engines left hand side, with the outer jet full of black oil, and the inner jet clean. The other side was the same. Is this how they should be? They don't appear blocked, but I need to remove them to really tell. How do I get them out? I guess the black ring around them used to be an o-ring...but it is so hardened with age I am not sure. Do I have to get them out and replace.....or should they just pop out?

(https://i.imgur.com/eRbdaX1.jpg)

That was where I left it for the night, with the next big job being lifting the head.

But I shall end with an amusing tale. ......
I had a mate with one of these back in the day. He had to replace the cam carriers after the top end went rattly. He found a lot of the bolts holding the carriers down had stripped threads, and invested in a helicoil set to sort the issue. He had never used one...and I had, so I went round to help. The offending threads were soon sorted, and I told him to make REALLY sure all the swarf was cleaned out before he put it back together. No bother...and I told him to get a proper set of bolts, as the issue has been caused by non standard bolts holding it all together. They were too short....and each thread had lost the fight. Yeah...... Went round the next day and it was all back together. He proudly fired it up and it sounded lovely. After a few minutes of idling.....there was what sounded like a burst of machine gun fire...and the bike ground to a rattly halt.
...Did you clean out hte threads like I said? ...... yes
..what did you use? .....petrol
..did you dry it out before bolting up? .....why?
..did you use the correct bolts...nah....the old ones were OK

Arrgh.... each hole had been left with a little pocket of petrol to heat up and each bolt was only 5-10mm into the threads. Every bolt had torn out. A brand new pair of cam carriers went in the bin....
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Laverda Dave on August 13, 2018, 12:55:17 PM
Great thread. 
I can't help much with your questions but as for dropping bolts down camchain tunnels, yep, been there, done that  ::).  What you need is an extendable long reach magnet to fish out any dropped nuts and bolts, you can get them on ebay for a couple of quid, here's one:

https://www.ebay.co.uk/itm/8LB-3-6-KILO-MAGNETIC-PICK-UP-TOOL-LONG-REACH-HEAVY-DUTY-EXTENDABLE-TO-24/302110467081?epid=1243243925&hash=item46572fe409:g:wawAAOSwLnBX3Xm1

Keep posting.
Dave
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on August 13, 2018, 01:33:56 PM
There are only 2 jets in the middle with o rings. On the outside there are just o rings.
Cam towers and there caps are matched, do not mix them. The tower cam journals can be measured with plastigauge  ;)

And don't forget you have 4 bolts under the pucks  ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Bryanj on August 13, 2018, 02:03:30 PM
Dont know what trigger would say but i rebuilt many with worse journals way back when and they were OK. By the way the cam does not have to be in a specific position to undo or tighten the sproket bolts, you can turn the engine between bolts but before you replace followers and pivots
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 13, 2018, 03:03:45 PM
Thanks Trigger :)

I will definitely be needing new o-rings.....and new pucks. Were those originally rubber? I really can't tell.

Plastigauge ..... I know of it....but have never used it. So as long as the clearances are OK, then the carriers are fine. I was worried about hte state of the surfaces on the lower half of the carrier. The caps are perfect. If those are OK, then I will re-use them.
As far as the caps go...I was worried someone had already swapped them about. The L and R marks etched in them just seemed the wrong way round. I was taught at an early age that what wears together stays together. But what do you do if it's not where it should be? Is it better to leave as is..... I probably will. Could well be I am over worrying :)

I am also going to need a good gasket set. Instant gasket is not something I approve of where it isn't designed to be.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on August 13, 2018, 03:35:54 PM
Dont know what trigger would say but i rebuilt many with worse journals way back when and they were OK. By the way the cam does not have to be in a specific position to undo or tighten the sproket bolts, you can turn the engine between bolts but before you replace followers and pivots

As you know Bryan, there is a picture and then what the naked eye sees  ;D


The cam caps never really have any ware unless the cam has had a problem. The cam is pulled down by the chain and pushed by the rockers.
Never seen cam towers with those markings before, they are usually marked on the sides with a letters .
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on August 13, 2018, 10:38:34 PM
This is how the match letters or numbers are on most towers. Don't build F2's so, not sure if the markings are different.

These are 100% fecked towers Bryan  ;) These are beyond capping and line boring back to spec  ;D


[attachimg=1]


[attachimg=3]
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Bryanj on August 13, 2018, 11:21:31 PM
Trigger, back in late 70's we had a man who subbed for Dowty and he would grind the cam bearings, bore out the towers and make split bronze bushes that were pegged to the towres and caps. This was when we had a standing order with Fowlers for a complete set of cam, towers and folowers which they could only supply every 2 or 3 months so more common to repair
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: philward on August 14, 2018, 08:15:35 AM
That's what I did with my Phil Read Rep Brian - when I had access to the right equipment at Bae

Sent from my Moto G (5) using Tapatalk

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 15, 2018, 12:14:04 PM
OK...still not 100% whether I should reuse the worn cam bearing surfaces, but I shall park that question for now. If a great set turns up at a pricve I can sort of afford...I will snag them. Failing that...it's a bridge I shall cross when I come to rebuild.
I already know I need a new set of pucks, and hte 4 o-rings under the carriers were so hard they would serve as washers...not o-rings. I tried to bend one....and it snapped. Haven't got the oil jets out yet, but I will need to use a needle or similar to pick out the o-ring. I won;t bother trying to be kind to them, as they will be just as scrap as the outer ones!

First though....I have to get the head off. Damn thing will not budge!

I have undone the 12 M8 nuts around the base of the cam carriers. I have undone the 4 dome nuts hiding by the spark plugs. I removed all 6 rock hard mini frisbees and undid the 4 M6 bolts hiding under there. I undid the M6 bolt at the front of the camchain tunnel...and the sneaky hidden one at the back. So ....16 nuts and 6 bolts accounted for. Head will not budge.

Much tapping with the rubber mallet...not a thing.

I have a very nice and undamaged set of fins...which I would like to keep... so before I get tempted to a lump hammer and wooden drift, or banging wooden wedges in between head and barrels....have I missed anything obvious? I have dribbled some oil down all the studs in the hope of releasing any sticky corrosion, which should just leave the 40yr old head gasket to shift.

I have taken heads off before...never one this old...but it seems like it is far more stuck down than it ought to be. Makes me wonder if I missed a bolt!

If I haven't missed a bolt...is there a good way to shift this thing without risking damage?

As a not very humourous aside....I noticed quite a few sellers on E-Bay offering cam carriers, rockers etc. for sale. In every case....EVERY picture was taken in such a manner that you could not see the bearing surface that mattered. DK Spares were asking some pretty steep priced parts like this, with the caveat of 'sold as seen' ... One other seller offered a set so chewed up it looked like a ploughed field. I know E-Bay can be a valuable source of material...and a valuable source of knackered junk too...but surely a legitimate seller would want to show everything.......
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Nurse Julie on August 15, 2018, 12:30:42 PM
Original Honda head gaskets are very, very sticky and can be a right pain, bordering on impossible to shift.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Bryanj on August 15, 2018, 05:46:21 PM
Always replace all rubber bits on rebuild
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 15, 2018, 07:42:25 PM
hell yes.... Julie mentioned it right at the start, and so far I have seen exactly why. The carb rubbers are like steel....the o-rings are brittle, the pucks had to be peeled off the carriers like old chewing gum off the sole of your shoe...

And that's just the top end.

I will be replacing every bit of rubber I possible can, as none of these items will ever seal, and would most likely crumble to dust. I do need to find a source of replacement rubbery bits though. Seen a few sets of 'engione rubbers' ... but no description of what's included. So will need to make a few phone calls before I unlock the credit card.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on August 15, 2018, 07:53:06 PM
I had a problem getting my F1 barrel off, one of the steel knock pins (corner one) had rusted and was holding the barrels to the crankcases together, it took quite a bit of gentle persuading to shift it without damaging the fins, maybe you are facing something similar, if you are certain that you have all the bolts out that is.
And Nurse Julie is correct that the original Honda head gaskets were extremely sticky and very hard to shift.
(https://imageshack.com/a/img923/681/XzkCBr.jpg)

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on August 15, 2018, 09:10:35 PM
hell yes.... Julie mentioned it right at the start, and so far I have seen exactly why. The carb rubbers are like steel....the o-rings are brittle, the pucks had to be peeled off the carriers like old chewing gum off the sole of your shoe...

And that's just the top end.

I will be replacing every bit of rubber I possible can, as none of these items will ever seal, and would most likely crumble to dust. I do need to find a source of replacement rubbery bits though. Seen a few sets of 'engione rubbers' ... but no description of what's included. So will need to make a few phone calls before I unlock the credit card.

I have a large stock of engine Viton 0'rings, pucks, engine seals and so on. Send me a list of what you require and i will put some prices.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 16, 2018, 09:38:37 AM
Thanks Trigger 😀

So far, I have o my got halfway down .. but the list is:

8 tappet inspection o rings
6 pucks
4 small ovrings for the oil jets and the other 2 oil holes.
O ring on cam chain tensioner plunger shaft

That's so far ..  the list will grow as I haven't reached the cam chain guides, guide wheels, crank oil seals, gearbox oil seals and suchlike

The cam chain tensioner rubber block is pretty rock hard, but I suspect that would mean replacing the whole shaft. The metal plate has very little wear though.

Dennis ...thanks for the tip. I have doused the areas I can with penetrating oil, and will let it sit for a day or two. I have undone all the bolts shown in the picture, so it is just gasket grip or something corroded in place. Could be time to start making some wooden wedges.....
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 16, 2018, 09:22:33 PM
In the red corner........the CB750 lump.
In the blue corner ....... the ameteur mechanic.

After 2 falls and a submission....off with it's head was the cry! Yes....we got it done finally.

As always, these things have good and bad...so lets kick off with the bad.

1) I am not the first guy in here, and there was a little tell tale mark where someone had pried the head off before. Nothing serious...but of note for me.

2) The 4 bolts under the pucks were different. 2 were clearly replacements lacking the cast in washer and being fully threaded rather than a plain shank.

(https://i.imgur.com/eNax8gp.jpg)

Now...the better stuff.....well...for me anyway!

The bores look really nice. No rust marks, no scoring and no discernable ridge at the top of the bore. I could see the horizontal hone marks but no evidence of vertical scoring or marks that looked anything like wear.

(https://i.imgur.com/D7HPVXd.jpg)

The o-rings around the studs were incredibly shot. One looked like a dead slug, and the others were crunchy. All will obviously want replacing. Going to need to clean out the muck around them too.

(https://i.imgur.com/2VH1yJS.jpg)

With the head on the bench,I did the old seal test.... pour a little fuel into each head..and see if it stays there. 2,3 and 4 were good as gold...but pot number 1 dribbled it's contents out through the exhaust valve. Not a surprise....I was told more than once on here that the exhaust valves were wear prone. The heads were pretty coked up, with quite a bit of carbon on the valves, but underneath things looked pretty good.

(https://i.imgur.com/c5jOzkr.jpg)

The barrels neweded a good clean from the oil I had dripped down there, mixed with some loose carbon...but once cleaned, things look nice. The pistons all look quite carboned up, but it all rubbed off pretty easily. Barrels off next, so I can check the piston skirts for wear. For now...I got some more oil soaking down the studs ready to lift the barrels tomorrow.



Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on August 16, 2018, 09:30:01 PM
Thanks Trigger 😀

So far, I have o my got halfway down .. but the list is:

8 tappet inspection o rings
6 pucks
4 small ovrings for the oil jets and the other 2 oil holes.
O ring on cam chain tensioner plunger shaft

That's so far ..  the list will grow as I haven't reached the cam chain guides, guide wheels, crank oil seals, gearbox oil seals and suchlike

The cam chain tensioner rubber block is pretty rock hard, but I suspect that would mean replacing the whole shaft. The metal plate has very little wear though.

Dennis ...thanks for the tip. I have doused the areas I can with penetrating oil, and will let it sit for a day or two. I have undone all the bolts shown in the picture, so it is just gasket grip or something corroded in place. Could be time to start making some wooden wedges.....

No O ring on "O ring on cam chain tensioner plunger shaft". There is a seal in the housing but, DO NOT disturb this as they were not a separate part  ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 16, 2018, 09:51:44 PM
Hmm...I dread to ask what happens if that leaks oil.... I suppose it's just splash lube there, but the rubber seal is pretty firm. Don't know if it is up to the job of sealing. But I suspect the solution requires handing over cash for a good used item in the hope that it is in better condition....
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on August 16, 2018, 10:04:39 PM
Typical looking USA wheel on the cam chain tensioner, chewed  ;)
Wait until you get to the oil pump  ;D 
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 16, 2018, 10:19:03 PM
I guess the oil strainer is where all the missing bits of ...well...everything... ends up. Bits of crusty camchain tensioner, bitsof o-ring, bits of gasket goo, bits of whatever fell in there. At least I know the pump was still working as the top end was wet with dirty old oil, and the restrictor oil jets were clear. I hope.

At least with the head and barrels off...the motor has got to the point where I can lift it up onto the bench without risking injury.....so I can wrestle with the chewed screws on the side casing and open up the bottom end.

In the meantime, though.,....I found a use for that old seat. Makes a perfect place to park my backside while I was working on the top of the motor.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Bryanj on August 17, 2018, 03:51:56 PM
Guessing from the pistons i would guess you need new guides as well as maybe valves
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: royhall on August 17, 2018, 04:51:18 PM
Typical looking USA wheel on the cam chain tensioner, chewed  ;)
Wait until you get to the oil pump  ;D
Are they different on the USA models Trig?
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 17, 2018, 05:12:23 PM
Got the barrels off today after a major fight....and hte pistons are really nice skirtwise. No signs of scoring or rubbing. I need to give them a bit of a clean as they are oily from the oil I put down there .... but them and the barrels look good to go back in as they are.

The head....yes. I have at least one exhaust valve not seating properly, and to be honest...I think it would be silly to put it back without replacing the valves and having new guides. I would also want to look into getting the cam plain bearings re-worked if that is possible. Still need to see what the main bearings are like.

Barrelslook fresh as a daisy inside....but getting them off. Not fun. Now...the K series engines have 8 little plugs with seals that fit over the top of hte barrel studs. On the F2, Honda decided to cut that to 4.... and that leaves recesses to collect condensation, muck and whatever. This had gummed up a couple of the studs, making it a job to get the barrels off. The only seal they have is a rubber one at the bottom....to make sure whatever gets in can't get out... A bit of surface corrosion on 2 of the studs, and a collection of crud which needed a good soak with oil before it shifted.

Camchain guide wheels are rock hard....as was the tensioner blade. Where they run on the chain, it has pitted the rock hard rubber. All fit only for the bin...

So...next job is to look for someone I can send the head off to.....not at all confident about refacing valves and seats, and fitting new valve guides.

Then source a full gasket set ( spotted an NE set on E-Bay which looks pretty comprehensive ) and will also pick up the camchaion tensioner parts to put away for the rebuild.

Can anyone recommend me a good engine paint? I want to strip and repaint the barrels and cam cover ( head will get done later... ) I want a nice glossy black finish :)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Laverda Dave on August 17, 2018, 07:30:08 PM
I took my 250RSA engine cases to I Cleenz Machinez in Penge, SE London.  The original black paint was a bit rough so I had them aqua blasted and repainted.  So far the finish has stood up well but the engine is apart again after a siezure (read my CB250RS rebuild thread for the full story!).  The painter did an excellent job, everything was properly masked, no overspray anywhere.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 17, 2018, 08:06:43 PM
I'll give them a call and see what's what :)

Meantime...i did solve one problem. The bike was leaking oil from, the alternator cover.... Just took it off and found out why. Only half the gasket is there. Plus 2 bolts had been put in that were obviousdly short, and stripped the thread from one of the lower bolts. All the screws are pretty rough...so I suspect I will not be putting them back. Time to buy that helicoil set.....

I also have my first unshiftable screw. Well....I knew it was FUBAR...but I had to try. Will have to drill it out to get the left hand gearbox cover off. I also have no way to undo the 3 screws on the end of the alternator cover as those are well rounded out. At least I can attack those off the engine with the cover off.

Can't complain...as 90% of the screws have undone nicely, and quite a few of them had been butchered before.

Also on the good news front, the pistons all look good. No nasty scoring and just light wear on the skirts.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: paul G on August 17, 2018, 09:17:42 PM
Things now moving along at a nice pace. Keep up the good work.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 20, 2018, 03:46:45 PM
NgggggGGNGggnnsngngdfkgnfdgngngnnn.....

that was the noise I made when I started cleaning the rest of the odds and sods off the frame. A random set of 'earth' wires seem to have been bolted on, which may have been related to the electrical issues I was told about before I bought. Especially the one by the coils..

The loom is quite corroded on the terminals and the wires seem to have lost a lot of the flex they should have. It's also been unwrapped around the headstock...which is usually an area of concern with a loom. That's where wires tend to break internally leading to all sorts of interesting 'amusements'. I had a Moto Guzzi that did that to me. First the horn would sound on full lock...then the lights would go out when you turned....and finally when I went to swap the head bearings...I found it had been arcing across the ball bearings...which it was using to earth everything up front.

I might go crazy and buy a pattern loom from Dave Silver Spares so I can refit a good set of fresh unbroken wires for the inevitable electrical fault finding. That's one to bear in mind.

I have enough stuff off the motor to make it light enough to get up on thw workmate now...so I can crack on and strip the gearchange side. I also need to get a 3 leg puller.... I did have one, but it seems to have gone AWOL. No idea where...but I must have lent it out, and not got it back. That's the danger with tools you use rarely. I presume it's a 3 leg job to shift the rotor off the end of the crank...

I also need to consider what I am going to do with the alternator end cover. It's a bit scuffed and needs either replacing or refurbishing as it is pretty grotty. Someone has tried to repaint it black with matt paint. Now...the screws holding the fixed magnet on to the case are chewed. One certainly is already pretty rounded off and I doubt it will shift. Not sure how much bolt length is going to be left if I drill it....and I can't use heat

The jobs and parts list is growing....but the whole thing is breaking down into smaller and smaller assemblies, and the amount of 'bike' left is pretty reduced. Soon...I am actually going to have to start spending money and doing stuff other than taking it apart!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: hairygit on August 20, 2018, 04:07:47 PM
A 3 legged puller wont stand a chance getting the rotor off, you need a tool (or a bolt of the correct thread) that screws into the rotor body, you will see it has a thread in it for that purpose, which screws in against the crank itself and pushes the rotor off. As regards the loom, if you can afford it and can get one, best plan with something this old that already has issues.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 20, 2018, 04:54:09 PM
Oh cool...so I just undo the bolt on the end, and screw in a longer one to pop it off. My old Guzzi used a similar approach, only you had to put a 6mm rod in and then screw the original bolt back in to pop the alternator off.

https://www.davidsilverspares.co.uk/CB750F2-(Single-overhead-cam)/part_326959/

It's £95 by the time the government has had it's 20% ... so it might be on the Christmas present list.....
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: hairygit on August 20, 2018, 05:22:45 PM
No, the extractor is a larger thread than the one that holds the rotor to the crank. If you look inside the rotor after removing the crank bolt you will see the thread inside the actual rotor. The extractor bolt screws into the larger thread in the rotor, and when it hits the end of the crank it uses the crank to force the rotor off.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: hairygit on August 20, 2018, 05:28:22 PM
Easiest thing to do is buy a bolt to do the job, M20x1.5 thread, say 60mm length, you can buy pullers on e-bay, but they rip you off price wise for what is basically a bolt!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: petermigreen on August 20, 2018, 05:29:12 PM
Oh cool...so I just undo the bolt on the end, and screw in a longer one to pop it off. My old Guzzi used a similar approach, only you had to put a 6mm rod in and then screw the original bolt back in to pop the alternator off.

https://www.davidsilverspares.co.uk/CB750F2-(Single-overhead-cam)/part_326959/

It's £95 by the time the government has had it's 20% ... so it might be on the Christmas present list.....
Plus postage ::)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 20, 2018, 07:27:03 PM
Easiest thing to do is buy a bolt to do the job, M20x1.5 thread, say 60mm length, you can buy pullers on e-bay, but they rip you off price wise for what is basically a bolt!

Thanks for that :)

I went and had a look, and found something that fitted so I could check the thread size. Interestingly...the oil filter bolt is exactly the same thread. I wouldn't use it for hte job...but it was easy to measure it and it is indeed M20 x 1.5 and screws into the thread. With the bolt out, I could see exactly what you meant. I will go and hunt a bit to see what I can get hold of to do the job :)

Peter ...everything these days is plus postage :)

But....I know I need a bundle of things, and postage is one of those things that get easier to bear when you buy more.

Currently I am trying to find a diplomatic way of explaining to the missus that the head is going to need an overhaul, with new valve guides, probably new valves and having the seats looked at. Then there is the possible need to sort the cam carriers. Haven't looked at the crank yet....but I can already see £500 in bills
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on August 20, 2018, 08:02:28 PM
Contact a member Paul G, i thick he bought a few bolts to get the fly wheel off.

If you need the valve seat done, do not let any engineer cut them. They like to be ground  ;)
And if the valve guides need replacing, then you will need the head skimmed. All this will need doing after any paint .
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 20, 2018, 09:44:04 PM

Trigger...thanks for that. I definitely want the valve seats done, as they are not sealing like they should. It also seems silly NOT to swap out the valve guides while everything is torn down. Of course...they may be perfectly fine....but I have had several people tell me the exhaust valves are poor on these motors. With unknown mileage on the motor I don;t want to leave things that could result in a smokey, rattley motor.

Also...I would have painted the head AFTER I got the work done. I suppose it's better to paint then skim, so you don't have to worry about paint getting in the way and you know the surface won;t have paint ridges to cause sealing issues. Need a guy to do the work who won't scratch the paint :)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on August 20, 2018, 10:46:42 PM
Contact a member Paul G, i thick he bought a few bolts to get the fly wheel off.

If you need the valve seat done, do not let any engineer cut them. They like to be ground  ;)
And if the valve guides need replacing, then you will need the head skimmed. All this will need doing after any paint .

Weird that in respect that the original tools in the front of the manual show cutters not the grinding machine we ended up using, never thought of that before.

That is a bit strange as was never sent cutters from Honda, only the grinding machine which i still have  ;)

I have seen engineers try to use a Serdi valve machine and make a right mess  >:(
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 24, 2018, 11:06:29 AM
Been a slow progress week.....so no pretty pictures to show for a few days.

Not been idle...but the pace has slowed.

I needed to go back througfh the bits pile, bag up, store and tidy the stuff I had dismantled. The cams were wrapped in clean rags, given an oil bath and then taped up in some thick plastic bags. Same for the cam towers, the head and the barrels. All the nuts and bolts have been freezer bagged, labelled and boxed up. It's made things a bit easier in terms of storage!

All the engine covers have been removed and I plan a visit to the family in a week or so. Dad has a stock of US spec paint stripper which I plan to raid. Stripper that still has hte old magic ingredient that strips paint...which apparantly is far too dangerous for us to use nowadays. He also has a small blasting cabinet. Going to take some sample parts down ( they are in Somerset...I'm in London....nice and local eh? ) and see how well I can clean them up.

Got to go out of town next week.....so I got to leave it alone for a whole week ...and just shop for bits ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on September 02, 2018, 12:26:05 PM
Back after a weeks hoiliday, and straight out to the shed to get the next steps done :)

While I was away, a package had arrived from Paul G. Many thanks!!!! It contained one M20 x 1.5 bolt.... and with just a short bit of spannering, this was the end result:

(https://i.imgur.com/A0GZdRL.jpg)

Popped off like a beauty. The starter motor gear parted as I slid the rotor off. Nice.

Not so nice was the 20 minutes I spent in the dirt and spider webs under the bench looking for the spring, little metal sleeve and roller that decided they would make a break for freedom. God...it's nasty under there! The bench I mean. Needed a sit down and a strong cup of tea once the parts were all cleaned of grit, swarf and I don't know what. Now for the fun task of putting them back in.

Some surface rust on the back of the rotor, but that cleaned up fairly easily. The rubber seal on the starter gear was rock hard....so don;t know if that needs replacing. At least the crank taper was clean with no signs of nastiness there.

Now I can get on to the other side of the motor and start pulling the clutch side apart.

Engine work wise....I now need to find someone to do the head/valve work I know needs doing. I have had some suggestions....all of which pointed the same way. To a certain very busy, overworked specialist with far too much work on. Plucking up the courage to ask....

Have not opened up the oil pump area of seen the crank bearings/shells yet....but want to try plastigauge and such myself. As long as the crank bearing surfaces are not scored or marked. If that is the case...then it's work beyond my meagre skills and will mean going back to the credit card/expert route.

Really am getting close to the part where I can start putting things together and painting...the parts I really like. Also.....the spending will commence soon. Normally I am as tight as a stereotypical Scotsman when it comes to cracking the combiination lock and waiting for the time-lock to tick over so the wallet can open. Once I have got it out from under the sleeping leopard that guards the Piranha tank I keep it in. But I am actually looking forward to buying shiny things to make her pretty again.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on September 02, 2018, 05:08:22 PM
Good that you are cracking on with it, though it's making me feel guilty as my pile of F2 bits are still sitting there on the shelves in the garage.

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on September 04, 2018, 04:25:54 PM
Took the plunge today to have a look what lay within the sump....gulp.

Popped the drain plug and caught the stuff that came out. I'll call it 'oil' ..... but that's a pretty flexible description. Lets see....

colour..bleurgh. I think British Leyland painted Allegros this colour.
(https://i.imgur.com/TxFyXCb.jpg)
It still felt like oil, but it was pretty thick and had a fair amount of sludge. I passed it through a cloth looking for big bits, but nothing found. So far...so good.

Next, I tipped the motor up and took the sump pan off.

More sludge, thick  gooey and grey looking. It looked like instant gasket...but when I squished it...it was just grey/white sludge and not rubbery.

The filter mesh looked OK with just a few bits of muck in there.
(https://i.imgur.com/F17OFNL.jpg)
Not sure what it is, but it wasn't metal and crumbled when rubbed between the fingers. Felt like gasket shavings. OK in my view...and nothing scary.

Lastly...I took the sump pan, and poured in a slug of white spirit to dissolve the sludge. Partly to clean it...and partly to see if it contained anything untoward. After it had been left and then scrubbbed with an old toothbrush, I dunked a magnet in there and swilled it around a bit. Picked up a very fine metallic 'sludge' which you can see on the magnet there.
(https://i.imgur.com/NaKb1Tt.jpg)
PC hard drives come with a lovely magnet in them, so whenever I scrap one, I keep the magnet for this kind of job :)

So....pretty boring really. In a good way! Of course, the motor spent a week lying on it's side while my failed attempt at engine removal / finger removal healed and bits could have got elsewhere, but hte main thing is I have not found gear teeth, bearing fragments or piston rings lurking down here.

Less good is the chewed up state of the screw in the end of what I presume is selector drum. It's chewed to hell. I hope I do not need to undo it.......Also there is what looks like the signs of previous crankcase seperation just behind the large bearing. Looks awfully like a screwdriver applied to break the seal. Hopew not....but that's what it looks like. Ho hum.
(https://i.imgur.com/CNTdCMj.jpg)

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: hairygit on September 04, 2018, 04:53:51 PM
More good news, even though the Haynes manual tells you to remove that chewed screw and dismantle the plate and pins, I have NEVER done it on a 750 motor, there's no reason to!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on September 04, 2018, 05:09:14 PM
Doesn't look too bad really at first approach.

Those four crosshead screws on gearbox bearing retainer are usually chewed if it's been apart but they look newer, so possibly been replaced as people generally butcher them.

The lever point by the bearing ordinarily come about either because someone hasn't taken all of the bolts out and tried to get it split,  or jacking up one side/end of the cases and getting them pinched on locating dowels. It suggests it's definitely been apart though.

That "sludge/paste" in the oil is what remains of the oil viscosity additive package that has broken down and dropped out of suspension in the oil.  10/40 multigrade oil is only ever a true 10viscosity and acts/simulates 40 when hot by use of the polymers used to give a pumped resistance equating to the higher number.  That's just the remnants of that chemistry laying around. 

Not scary so far,  just normal stuff. Be interesting to see as you get further inside.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on September 04, 2018, 07:00:25 PM
K2-K6 ...thanks for the info :) I did wonder what the hell that goo could be....and how it got there.

hairygit....good to know I don;t need to take that apart. That's only coming out after it gets drilled....and I hate drilling  screws out as you never know the first time whether you will have any meat left on the shank to get the stump out. So far only one screw has needed the DeWalt treatment and that was one I knew fropm the screws around it was plenty long enough.

Presumably that whole assembly can come out in one piece...or do I just leave it in situ when I split the cases?

If I damage one of those 4 big screws I will make sure I fit new ones before I rebuild. Never know when you need to go back in.....
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: hairygit on September 04, 2018, 08:07:54 PM
Take it out once the cases are apart, can't clean the casings properly with it left in place, comes out easily
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on September 12, 2018, 04:12:27 PM
Progress has been a bit slower over the last week or so, due to family stuff....and those inconvenient bits of life that stop you doing what you want to do ...but we still push on.

Made myself a tool to undo the clutch centre nut, which I reckon will do the job. Second attempt...first attempt scuffed the nut...so I might well fit a new one on rebuild. The final tool was basically a 6" section cut from an old Trriumph fork tube. Dad has a good supply of these....all rotten...after many a front end rebuild on bikes he has renovated. They score up and the screw on bushes corrode in place. Replacement is the only cure. He keeps the old ones to make spacers, drifts etc. and to stick yokes on when painting, so I was able to get a piece to bring away. Chopped it into a 4 peg array...which was about 1mm off on the internal diameter and slipped scraping the nut. Mk2 was fitted iwth an internal sleeve epoxied into place to line up right....then drilled through for a tommy-bar to turn it.

That's when I hit problem No2.

The damn thing won't stay put! I made sure it was in gear before I took the shifter mechanism apart, and sure...it is in gear. I just haven't figured out a way to stop the sprocket turning!

I tried a wooden block wedged in, I tried wrapping the chain around..... damn thing doesn't stay put when I put proper pressure on the nut. GAhhhhh.....

I know the time to step back from the problem was at ahnd, as clear thinking was the order of the day, not aided by building frustration, so I found something else to occupy my mind!

The frame is in need of a good clean, and a light respray. The more I stripped it, the more I realised it actually has a lot of good original paint, which I can flat back and recover. Other areas need more work...but I like the idea of keeping as much as I can, and just perking it up a bit. The centre stand had to come off, and that was nice and easy. Just slacken the pinch bolts and drift out the pin. Stopping only to extract the drift I had wedged in ..... and found a better one that didn't get stuck it was soon free along with it's spring and half moon spring bracket. Side stand off next, followed by the seat catch. Now she is ready for proper cleaning and sanding back.

Next stop the seat.

Now....this thing is a horror.....humped semi K&Q thing with crunchy vinyl and buttons down the centre. Yes....buttons. The seat pan looks to be usable, but the cover has been rivetted on, and the buttons have also been rivetted through the foam to the base. There was some rot to the sidestand low side of the base, but it looked pretty solid, so I had ideas of using it for a new seat. I planned on a cafe style seat, long enough to look good with the frame rails uncut ( I don't want to ruin ANY parts originality, to make it easy to revert to stock if I wanted.  ) so I thought I could use the front half of the pan, reshape the foam, then get it covered. That way the hinge and locking points from the stock frame can be used with a GRP rear section glassed in and fixed to the rear.  That....as they say...was the plan.

The cover needed cutting off, which was done, but I could feel a lot of 'crunchiness' around the edges....

Oh dear.

(https://i.imgur.com/hqy97xZ.jpg)

Half the seat base metal is still glued to the foam buy it's own corrosion. The side sections at hte front are largely gone at both sides, wioth metal so thin the screwdriver 'poke' test failed all along. I emptied out hte contents of the vinyl and foam.....and got this.

(https://i.imgur.com/ytm00K3.jpg)
Going to stick it on E-Bay as genuine 1970 Honda iron oxide, rare and original. Can be fitted to all 70's honda motorcycles. Came as standard with many models......... £7.50 per bag. Bargain. Woin't be here long at that price. Of course...I will give a discount to SOHC Forum members ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Moorey on September 12, 2018, 04:30:46 PM
Somebody will buy it and restore it.  ;D
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: hairygit on September 12, 2018, 05:55:56 PM
If you advertised it as Honda iron oxide, you'd get negative feedback coz that seat is obviously NOT Honda, some vile aftermarket thing the yanks seem to love! And the way they have been with DS and others, Honda themselves would probably sue you!

Sent from my X6pro using Tapatalk

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on September 12, 2018, 11:11:54 PM
The seat base may yet serve a purpose.....as a mould to make a fibreglass version.

I'll amend my E-Bay ad to read 'Rust taken from a Genuine 1978 Honda's seat' ..... and reduce the price to 50p per bag ( £7.00 postage )

And yes...that seat was vile. Combined with a lovely pair of high rise bars with stupidly swept back ends. There is no excuse for either.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Rob62 on September 16, 2018, 02:23:09 PM
Engine doesn’t look too bad inside, bit of sludge in a 40 yo motor...... you can buy a new seat pan off ebay for 40 quid, why mess about with fibreglass.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on September 22, 2018, 11:38:51 AM
Clutch is still an issue...and I need to take a step back and work out a proper solution to lock up the rear sprocket before I damage something in frustration. In the meantime...I have turned my attention to other bits and pieces and am working my way through the shelf of shoddy and appraising what I have/need/should dicard.

Which brings me to the point of todays post....

I have a lot of small odds and ends that are a bit rusty...but which were originally plated. things like the metal cover plates under the footrest rubbers, the insdie of the pillion pegs, the pins that go through the pegs. All things that while they were not really rusty....had worn the plating off...or have a bit of surface corrosion.

Now...I could bundle up a whole load of things and send them off to a plater...but I don't have anywhere local and I am not sure who I could trust to actually send me back things. I could try and replace....or...I could try home plating. I would rather refurbish original parts rather than replace unless I can get genuine parts. With footrests...I will use pattern rubbers...but not the other parts. I have bought cheap e-bay footrests before....never again. I only did that one time as I was selling the bike and tore the end off the rubber on an overly tall traffic island....

I have no problem cleaning up and polishing the parts...but wondered how easy/successful home plating actually is...or if it's best left to the pros.

If the latter....is there anyone in the southeast I can use who knows their stuff...and knows what a MOTORCYCLE is?
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Nurse Julie on September 22, 2018, 11:51:21 AM
Always re zinc or powder coat if you can. There is no guarantee that if you source new parts, they will actually be the same as what was originally fitted, especially with parts classed as 'Genuine', which is not the same as 'Original' and then the superseded parts numbers, which have been superseded again...it's a minefield.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: kent400 on September 22, 2018, 12:55:28 PM
There's www.colmorfinishing.co.uk based in Borough Green Kent. Small operation, little more than one man and a dog. Always seems to be a fairly quick turn-around

Picked up these a few days ago charged £40. Think there were 14 of them.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: UK Pete on September 24, 2018, 08:16:12 AM
There's www.colmorfinishing.co.uk based in Borough Green Kent. Small operation, little more than one man and a dog. Always seems to be a fairly quick turn-around

Picked up these a few days ago charged £40. Think there were 14 of them.
I might try these people out it's quite near for me
Did you have to do any prep, I might see what there coming prices are like as well

Sent from my SM-G930F using Tapatalk

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 04, 2018, 04:32:24 PM
It's funny....but some days go from triumph to disasdter in very short order.

The triumph first.....
Having given up on the home made attempts at making a clutch tool, I had oprdered a cheap one from China as a whole lot of Hondas seem to use a 24mm peg spanner for clutch centres, and I got one for the princely sum of £4....posted....so I figured what the hell and bought oner to give it a go. Took a couple of weeks to turn up, but worked brilliantly. Was a tight fit in the pegs, and a few judicious taps on the ratchet, and the nut came loose. Hooray. Notoced some odd scratches on the back of the clutch centre...but nothing too bad looking.

Ot came the clutch centre and all the plates. Some wear and tear...but usable. Will need a good clean as they are gummy and fairly well stuck together but there is enough left on the friction plates not to have me running off to buy new. I might.....but that depends.
(https://i.imgur.com/aClyiDT.jpg)
Dug out the puller, and gave it a quick mod to thin it down to use the hole near the gickstart gear and stay nice and central. Found a plug to fit into the end of the shaft to ensure no damage from the puller. Figured all was good to go.

Dug out the circlip pliers to remove the large circlip on the shaft at the centre....and found the clip came off really easily. TOO easily.......
Popped the basket off and had a good look at the end of the shaft.....and the swearing started. Lots of it. Loudly. Some things got kicked as well.
(https://i.imgur.com/WZhspAa.jpg)
The ends of the shaft where the clip should locate were rough and jagged. A quick delve in the oil pools under the clutch found a few fragments that clearly used to live there.
(https://i.imgur.com/af6V8Xr.jpg)
Now I don't think the engine was run like this....as the shards were clean and sharp but I now need to find out what I have to replace...as I cannot rebuild it like this.

Looks to me like someone removed the basket with a crowbar and never took the clip off. I counted 7 'broken' places on the shaft....and have 3 shards. When I split the cases I am going to have to look REALLY carefully as the other bits have got to have gone somewhere. If I am lucky...they fired out when it happened. At least they were not in the top end, the sump or the oil strainer. The bits I found were in the dimpled recesses in the bottom of the clutch area.

Gave me that sick feeling when I found them....and a sudden pain in the wallet area.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on October 04, 2018, 04:52:12 PM
Oooooh, that doesn't look good  :(

What is that marking on the bearing housing at about 11 o'clock?  Is it a shadow of casting mark or damage?
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 04, 2018, 06:07:08 PM
Casting mark as far as I can tell.

I have been studying all the pictures I have of the gearbox shafts etc. trying to work out exactly what it is I have to replace here. I assumed it was the end of the layshaft...but none of the manual diagrams I have seem to look like what I am seeing.

The damaged splines are the ones for the clutch basket....and the smaller ones for the clutch centre. So presumably...the inner part is not attached to the outer part.

What part is it I need to source?
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on October 04, 2018, 06:19:34 PM
The drive comes in to the outer clutch basket from primary drive assembly through that damaged hollow shaft. It's this component that will have to be replaced.

It gets transmitted through clutch plates and clutch centre to the central shaft to gear assembly,  passing back through that first hollow shaft. Which appears undamaged.

Hope that makes sense  :)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 04, 2018, 06:34:40 PM
So that's part of the primary drive sprocket.....not one of the gear shafts. That makes sense.

Now I got to go find a replacement one. Happy days.....
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on October 04, 2018, 07:31:27 PM
I see that kind of damage more and more these days. Test the shaft once out to see how true it is  ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 04, 2018, 07:41:03 PM
Oh....true...didn't think of that.

Thanks for cheering me up Trigger :(

But yes...if they put a load of brute force on the thing pressing down on the shaft, it may well be banana shaped. And if it is, then my gear mesh is going to go to hell in a handcart.
I was always told if something doesn't move and you think it should STOP. Find out why it won't move...don't just apply more force.

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on October 04, 2018, 10:23:30 PM
There are two types of primary sprockets, the early ones never had a circlip

[attachimg=1]
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 05, 2018, 09:44:49 AM
So any later sprocket would fit. From the pics I was looking at...late K models have the circlip groove.

Whilst I am sure the earlier design is OK and teh clutch centre nut holds the whole assembly in place...I presume Honda changed the design for a reason. And I would much rather my clutch basket was held on the shaft rather than floating free.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on October 05, 2018, 10:24:36 PM
The one you require was fitted to some K6 units, all F1/F2 and K7 and K8 units  ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 06, 2018, 01:50:24 PM
Brilliant. Thanks Trigger. Now I can go shopping!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 09, 2018, 04:30:29 PM
Been one of those days. 2 steps forward...2 rakes trodden on. That kind of day.

Stopped off on the way home to pick up some fresh drill bits to drill out the offending screws if needed ( my 6mm was blunt and I had snapped my last 4mm for pilot hole drilling to keep it centred. Helps get past the awkward bit where teh drill has to get trhough the centre of the cross ... and to the shed I went!

One last try with the impact driver and my largest hammer was called for, before I broke out hte drill and dived in.

Bang...bang...bang...shift. YES! it moved! One screw out.... on to the next.

Bang...bang...bang...shift. YES! The bigger hammer was a success and the overnight soak in penetrating oil had probably helped too.

No stopping me now!

Bang...bang...slip. That didn't feel right. Not to worry I thought, just means I have to drill this one out. Well....not exactly.

(https://i.imgur.com/qOolKJs.jpg)

The bottom left screw head was still perfect. It was just full...of impact driver head. Bugger. Damn thing had broken up! A funeral service will be held later. IOty had been a loyal servant and had fallen in the line of duty... Now I got to go buy another one. No way was I going to try another impact bit, as none of the others fit the screw, and I was not going to even bother trying an ill fitting one. Just going to mash the screw to no purpose.

(https://i.imgur.com/sO0yFsa.jpg)

So...I figured I would move on to another less strenuous task where an impact driver was not going to be needed ( probably... ) and I started on the carbs.

Floatbowls came off easy, and still held liquid. Probably petrol once. Wouldn;t call it that now. But liquid all the same. Usually makes life a whole lot easier when they are not completely dry....unless they were properly drained. Which they were not.

Jets were a bit gunked up but they all shifted easily and the emuilsion tubes came out after. Not...with...as usually happens. I alwys get nervous with brass screws, as they snap easily under stress and strain. Bit like me.....

Next I popped the carb tops off and all looked pretty clean. Slides etc. are not an easy strip on this type of carb...All rods and linkages rather than old fashioned screw top carbs. I noticed the throttle cable bracket was a bit wobbly...and needed a tighten up. Nope. It was tight. Then I saw the issue.

The bracket is held on by a single screw and a cast in pin on the carb body. That pin was no longer part of the carb body. Worse...the stress had been applied to the cast boss on the carb body....and that had caused a crack in the carb body. Wish I had never looked now.

(https://i.imgur.com/fpbjxyz.jpg)

Now...I could fix the pin with a drill/tap and screw a peg in. Not sure about hte carb body though. I mean...I could bodge a fix with chemical metal/araldite....or I could get it welded up...or source another set of carbs. The question is...whether I can get a good set of carbs, what they will cost.....

Fixing would mean taking the carbs apart from the mounting bracket. I have never done this...and have...in the past...done EVERYTHING to avoid it. All the shafts and springs and whatnot all need to be properly aligned, and choke flaps ahve to come off...and so on. But any fix is going to need access to the side of the carb...and it's one of the inners...

But I need to make a decision on this before I go any further with the carbs, as any kind of cleaning and fettling is going to be a waste of time if the carbs are not usable.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: paul G on October 09, 2018, 04:46:32 PM
It always seems to be surprise after surprise with these things and most of them are usually unpleasant ones. >:( >:(
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on October 09, 2018, 05:17:35 PM
May be proved wrong,  but never considered the carb's material weldable.  Not sure of the alloy but think it has a zinc content that oxidises at below weld temperature,  which prevents normal metal flow. That's the bad news  :(

The good is that the crack appears to be in an entirely non critical part for normal carb structural function. Doesn't look like it's used for the throttle slide to bare on,  so you should be able to make an epoxy repair into the crack to prevent air leak potentially affecting the mixture  :)

To get a realistic repair,  I'd clean it with carb cleaner,  warm it and get plain epoxy two pack to flow into the crack,  leave to set and clean off excess with a blade.  Don't try to flex the casting in any way at all,  it'll probably snap off.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on October 09, 2018, 05:41:44 PM
Just a thought on the impact driver,  it hasn't flicked it to doing up has it? Just sometimes they bounce past the centre point if you don't hold them against the screw tightly.  If it has,  that may have snapped the bit.

I usually pre-load it slightly by holding  the smallest amount of anti clock rotation on it before thumping it.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 09, 2018, 07:12:23 PM
No...the impact driver was fine. I do the same as you do K2-K6 ... I apply a little bit of twisting torque to the handle to make sure it is in contact with the screw surface it's going to press on. It also helps to let you 'feel' the thing turn when it starts to go.
I think the bit has just failed through long years of use. The large cross head is the one I used the most...and it's life is one of shock loadings. It's just called time.

Going to be a deep breath job if I have to seperate the carbs...but in order to fix the sheared pin part, I will need to do this.

No way I would try to move the thing back...made that mistake before. You think..I'll just ease it back...ping.

The slides don;t go that far up, so I will try an epoxy repair. I will also...assuming I get it all apart...stop drill the crack before I epoxy and maybe just 'V' the inner side a little to help the epoxy bond.

There also is a small grommet on the accelerator pump that has cracked and broken in two. It's part of part number 16201-393-004, and seems to form a seal and a support to the shaft on the accelerator pump. I can't tell if it is plastic or rubber.....but I think it was once rubber. It may explain why there is corrosion in the area below the diaphragm. Need to find a replacement for this while I am at it. Then order a set of carb rebuild kits..... but not until I have done the deed with the carb body!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Bryanj on October 10, 2018, 01:06:22 AM
Got a set of 550k3 carb bodies you cab have cheap plus postage, i know that a lot of the internals are the same but not sure on the bodies. Have you got the pilot jets out to clean them? They clog up for a passtime, are a press fit and you need to twist and pull with vice grips
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 10, 2018, 08:31:55 AM
Thanks Bryan....I'll do do e research and find out if the bodies are the same. Aside from the crack ..the carbs are not bad. Not taken the smaller jets out yet. Much still to do!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 10, 2018, 12:43:49 PM
Mixed dasy today. No work as I had a dentist appt...so some sneaky work was done on the motor.

Picked up a replacement impact driver as it was £8 to get the bit I needed....or £15 for a whole new one from Halfords with a lifetime guarantee. So....no brainer really. I got a few extra bits to replace ones that had been lost over the 30 years I had the tool...

It is only when you replace a worn out old tool with new that you realise how much slop has grown with time. New driver...3 taps...2 screws out. WOW. Didn;t even need a big hammer.

Flushed with success and with half an hour to spare, out came all the top bolts and into the prepared piece of card with the holes laid out...Flipped motor over. Lost the little screw in the top of hte neutral indicator thing I can't shift from the upper case...must go find that later. Undid all the bottom case bolts, breaking the torque in a sensible stress relieving pattern....gave the cases a few judicious taps on the big bits where the engine mounts are. Saw it shift. One section wouldn't budge. Resist the urge to 'pry' as I have seen a couple of minor scars on the cases where someone did...Find the bolt I forgot to undo after I slackened it...which forced me to turn the motor back over to get to it...then back over again...and hte cases parted like the Red Sea before Moses.

The Halleluia Chorus was playing on the MP3 and hte sun came out from behind the clouds.....

Nothing horrid met my eyes. I have not had time to check the shells or actually lift the crank out as I was now late for the appointment...but I am sure they understood. No time for photos either...so will do that later.
what I did have time to see was the state of hte crankshaft journals.

I had feared something looking like an aerial photo of a railyard.....rust....furrows....metal fragments. All these things were not there.

Instead, I could see a shadow line where the oil channel is in the shells, which was wiped with a lint free cloth....revealing a polished surface of shiny loveliness. I could not see a mark on the bearing surface. Not one. Which is how it should be. Running a fingernail across was smooth on all 4. That's a relief. Really is. Big ends all felt rock solid.

Of course...I haven't measured the clearances on the shells ( I have heard of Plastigage....understand the process...but it's not something I have ever done.  )

Also...I am reluctant to mess with the big ends, as they all seem smooth and free from any slack I can detect. Should I? Or should I not. Bottom end on this thing looks really tidy aside from the gorilla knackered primary sprocket shaft and some idiot marks on the cases .

Also need some gasket sealant for reassembly ( Hondabond isn't it ? ... won't have instant silicon stuff anywhere oil lives )

After the last couple of days of hassle...today has started well.

Aside from the dentist.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 13, 2018, 12:44:43 PM
Stripdown is very, very nearly finished....and I am at the take stock stage....

I only have that annoying roll pin to get out to free off the kickstart shaft and the cases will be bare. How in the name of god does that thing come out? Do you just ruin it with molegrips...or can it come out in a state where it can ever go back in again. I assume they are available...
The other 'sticking point' is this damn thing...
(https://i.imgur.com/rJa3gs1.jpg)
Which seems fused on the shaft. Much WD40 and waiting. I have budged it around half a mill....if that. The soaking continues.

Had a good look at hte bearing shells in teh harsh light of day.
(https://i.imgur.com/nbd4GHt.jpg)

(https://i.imgur.com/jpkAktN.jpg)

Don't look too bad, with only one of them really showing signs of wear. Don;t know whether they need replacing or if they would be OK to re-use.

Crank looks good...

(https://i.imgur.com/aEDkLR1.jpg)

Less good, with them free from their prison...is the rods. Quite a lot of surface rust. I assume this is a relic of standing long time. The rods themselves would only have got splash lube, and once the oil dried off...they were sitting in fresh air. The bores were fine, but....not the rods. Big ends feel smooth with no slop or noises. So....can these go back in...or do I need to budget for fresh. I'm out of my comfort zone here!

While I was in.,.I did notice something odd. I guess this might be further evidence ( if any were needed ) that someone was in here before me. The damaged clutch shaft...pry marks on the cases...and this. I assume the Japanese do know that 4...comes after 3.... Not here. By rods are labelled 1...2...3...and 3. That's not factory fit surely.

I also noted the pistons look more worn than I recalled when i popped the barrel off. I guess teh shiny oil has wiped away and with them in good light ( as in...not on the rods) it's a lot easier to inspect them. I have refitted worse....but that's something else I need to think about.

The crankshaft oil seal on the end was utterly buggered. I would be surprised if it kept oil in very well. Not as bad as the final drive seal though. The dried up chain grease was doing a better job of sealing than the rubber part.

One last thing.

I noticed a bit of marking on the bearing surfaces where the roller bearings for the gearbox and final drive sit. Is this normal? At some point some of those bearings look to have shifted. Do they need a few drops of bearing fit on assembly? Or has the case not been gripping them due to other issues? It's something I do not want to happen again.

Now to sit down and start writing up the shopping list.....and work out how long I am going to have to save up to afford what I need to do.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on October 13, 2018, 01:52:40 PM
Nothing wrong with those rod numbers, it is the letter code that is important as this is the weight and should be all the same  ;)
The roll pin can be a bugger sometimes, if you can't get it out with grips then, tap a thread down the middle, insert a bolt and pull. If you bugger it, don't worry as i have a tray full of NOS ones.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 13, 2018, 02:02:57 PM
Good idea on the thread thing....I'll give that a go.
Also handy to know where I can get one if I mangle it!

I'll also check the letter codes on those rods.

Not going to leave the kickstart in place as I want to properly wash, strip and paint the cases and that means no roller bearings around!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 16, 2018, 12:04:23 AM
Today...the engine strip was finally complete.

The pesky pin needed mole grips to 'squash' it enough to get it free. It's out....but it will need replacing. Tried threading it....was perfect for an M4 ... but the bolt wasn't able to handle the pressure and every M4 bolt I put in just stripped as soonas I put it under load. Brute force won the day.

Similar appraoch with the gearbox sprocket. That finally succumbed to a combination of penetrating fluid and violence. It was REALLY stuck on the splines. Had to come off though. The dust seal was shot and wasn't seated in the cases right. Grit had clearly got past it as the large bearing was making that grinding noise bearings make when they want to be thrown away. The smaller inner bearing was notchy too. See no good reason to put a rough bearing back in the cases....don't plan on pulling it all apart again that soon!

Packaged everything up, cleared the decks and tidied up. Next job is to strip the chipped and flaky paint off the cases, clean them back and get a coat of black engine enamel on.

I also have to put together parts list no1 .... the bits to replace for the bottom end.

1) Primary chains...more slack than there ought to be
2) Primary chain tensioner... the spring was weak and the wheel rock hard.
3) Camchain. Why not.....as the crank is out.
4) Final drive bearings & seal
5) crankshaft end seal.
6) roll pin for kickstart.
7) 4 new screws for gearshaft bearing carrier.
8) Any o-rings lurking around...there are a couple between the cases.
9) Order gasket set & Hondabond

Jeez...long list! I was expecting the project to soak up a couple of grand before I was done....with the largest slice of that going into the engine. So here goes.......
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on October 16, 2018, 06:30:29 AM
1) Primary chains...more slack than there ought to be >> I always replace as, you don't want to be going in the bottom end again.
2) Primary chain tensioner... the spring was weak and the wheel rock hard.>> Once hard they start to get little chips.
3) Camchain. Why not.....as the crank is out. >> Upgrade with a FTH and check the midwheel, tentioner and guide.
4) Final drive bearings & seal >> Check all the bearings in the gearbox and the clutch lifter bearing.
5) crankshaft end seal. >> All seals come in a engine seal kit.
6) roll pin for kickstart. >> PM me your address and i will pop one in the post.
7) 4 new screws for gearshaft bearing carrier. PM me and i will pop a set in with the roll pin.
8 ) Any o-rings lurking around...there are a couple between the cases.>> There are a few o'rings that will need replacing, 1 on the main oil gallery bungs and 2 on the bottom bungs, 1 on main oil gallery blanking bung, 1 on the neutral switch, 1 around the crank case dowel, 1 on the clutch lifter rod. 1 on gear shaft carrier ( I always upgrade these to viton )
9) Order gasket set & Hondabond >> The engine will leak oil without them  ;) ;D
10) You will also need a oil pump rebuild kit.
11) Don't try to remove the engine studs unless they are very rusty  ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: paul G on October 16, 2018, 08:08:16 AM
Coming along nicely  :D As Trigger said replace ALL the gearbox bearings (I did) false economy not to as in the grand scheme of things not that expensive and you don't want to be going back in in a couple of years  :o :o Trigger may have them if not Yamiya are cheaper than Silver even with the post and capture fees.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: UK Pete on October 16, 2018, 10:06:46 AM
Great work love your enthusiasm , the engine can swallow sooooooo much money it's a case of if you you do one thing you have to do the lot then all of a sudden 2 thirds of the budget had gone on things you can't even see


Sent from my SM-G930F using Tapatalk

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 16, 2018, 10:44:59 AM
Do I need a bearing puller to get the bearing out of that layshaft bearing holder?

Cosmic. Just great . .... My PC is dead. PSU has failed I think.  But it means my only internet access is by phone now. That's delayed my part ordering to next month then 😭
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: hairygit on October 16, 2018, 12:20:41 PM
Do I need a bearing puller to get the bearing out of that layshaft bearing holder?

Cosmic. Just great . .... My PC is dead. PSU has failed I think.  But it means my only internet access is by phone now. That's delayed my part ordering to next month then
Don't panic, a PSU can be found on e bay for reasonable money, and are very easy to fit, you're looking at £15-20 for a decent one including delivery. 4 screws hold the PSU in place, all you do is undo the screws, the PSU comes out from the inside of the casing, screw the new one in place, then swap the plugs into the motherboard one at a time, that way you can't go wrong. When all of them have been swapped over, lift the dead unit out of the casing, refit the side, plug into the mains and you're done.

Sent from my X6pro using Tapatalk

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on October 16, 2018, 01:34:44 PM
Do I need a bearing puller to get the bearing out of that layshaft bearing holder?

Cosmic. Just great . .... My PC is dead. PSU has failed I think.  But it means my only internet access is by phone now. That's delayed my part ordering to next month then 😭

Very easy to get the bearing out of its housing, pop it in the oven for 10 min and tap it out on a block of wood  ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 16, 2018, 09:57:54 PM
PSU problem sorted :) The fan had failed, and it was stalling...causing the unit to trip out. Wasn't overheating...just pulling too much current..and there must be a trip out in there that was popping. Cut out and soldered in a new fan. 5 minute job. That sorted that. Then I found I had another problem on top of that ...which I traced to a Win10 update. Causes a misdirection to the boot ini....leading to a 'boot device not found' error. Had to manually remove the package in DOS ( I am old enough to have used this before! ), boot into safe mode and upload the fix patch. Wasted half a day....but it cost me nothing.

I'm on safe ground when it comes to PC components...and electronics in general...but thanks for the tips HairyGit :) I was more stressed by the possible side issues of a fried PSU. Last time I blew a PSU it spiked the motherboard and it was toast. The thing is about 5 years old...so you then have to weigh up whether it's worth buying a motherboard for outdated CPU and RAM....and before you know it...£800 has piled onto the credit card. Money I want to spend on the Honda!

Still...on the plus side....my primary chain sprocket arrived today. £30 plus postage. The guy was selling it with a pair of chains and a tensioner. Both used...but he wasn't keen on splitting. Originally he had wanted £40...but a bit of haggling and I was happy. It's in decent condition and certainly as good as the one I have taken out. I guess the guy didnt want to get stuck with a chain and tensioner nobody would ever buy. I now have 2 sets of worn chains and 2 tensioners with saggy springs and hard as concrete wheels. Ain't I the lucky one :)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 27, 2018, 02:13:59 PM
Today we got something useful done. Aside from cleaning and trying to get paint and rust off..... we sorted the broken No2 carb.

The problem was the bracket that holds the throttle cable. The bracket locates to No2 carb with a screw and a peg cast in the carb body. The peg had sheared, using a little cast nub on the carb as a stop...and that had cracked the top of the carb body.

The mission....re-instate the peg and patch the body to keep things airtight.

(https://i.imgur.com/RjqVpoi.jpg)

The flat square area just above and right of centre is where the peg used to be. I checked the depth of metal, and drilled a 1.5mm pilot hole as near centre as I could. I checked the depth and made sure I did not drill too far in so as to break through into the carb body and cause more issues than I solved! The bit I had that split was above the machined part the carb slides move on...but this is not. So blind hole it must be!

After the 1.5...we went again with a 2.5mm and tapped it with a 3mm thread. Fortunately...I have all this stuff in small size for my other hobby...Rc cars...and I also had a good seelction of cap-head M3 bolts. The heads on these were a close match to the original peg. The plan being to screw one in to form a new peg.

The bolt head was a bit too big...but shoving it in the drill and running it over a fine file soon had the thing down to teh size I wanted. A quick dip in solme silver paint made sure it was rust proof again! I hate tapping threads with small taps and blind holes....you have to be SO careful not to bottom the thread as it will strip it or break the tap. Neither would make me happy.....
(https://i.imgur.com/AU5Fu2q.jpg)

The bolt was trimmed to size with the Dremel, using the old 'put a nut on first so taking the nut off cleans the thread' trick. Screwed the bolt in with a dab of threadlock to make sure it stayed where I put it. It all went together like a little sweetly :)
(https://i.imgur.com/u5JLb1A.jpg)

The final step was to stop-drill the crack to relieve pressure and to channel the crack a little with the Dremel to make a nive valley for the epoxy to sit in. Tried to build a little fillet of epoxy on the outside to support the crack, but not so much it wasn't neat anymore. A little brush over with aluminium coloured paint on the outside should help to hide the repair if the epoxy yellows.
(https://i.imgur.com/yzqYjxC.jpg)

The bracket sits nicely and the peg should be stronger than the previous casting ever was.

The only slight issue with the job was the half hour I spent looking for the screw that holds the bracket in. I checked in carb bag 3 ..... and there was no trace. Checked the bench, the shelf...everywhere.

The mystery would have been solved quicker if I had remembered the bracket was on carb 2 ...... no harm done.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on November 08, 2018, 02:38:24 PM
Not had much time to work on the bike over the last couple of weeks, but small progress has been made. Work has been interfering but the worthless bunch of petty ingrates who employ me have allowed me the grace to spend some time otherwise engaged while they work out whose lifeless corpse they could best employ to climb higher up the greasy pole.....

That aside....

I thought I would have a go at breaking down the forks so I could get them sent off for rechroming while I figure out how one goes about measuring crankshafr bearing clearances.....

wish I had chosen something else...but oh well.

I have had many a fine tussle trying to undo the damper bolts at the bottom of the forks, and expected the same again here. Nope. Both undid really sweetly with just the pressure opf the spring stopping the damper from turning. This was clearly just the old beast trying to lull me into a false sense of security....

Next I went to undo the fork caps and get the springs out. Had to bolt the tubes back into the yokes to grip them, but hte first one undid. The second one did not buidge. Will not budge and broke free from the vice damaging the steering stem bearing cover that was still on it. The top nut has started to chew and still the damn thing won't budge. Breaker bar and the thing will twist in the yokes before it undoes. Tried shocking it and no joy. Next...I suppose I will have to try heat. I suppose the o-ring in there will want replacing anyway...

Anyway...Out with the damper bolt so I could get the tube out and remove the old seal. A lot of rust under the dust cap when I finally got that off. It was cracked and rock hard. I soaked it in ht water and pulled it out with moile grips like a rotten tooth. Then I pop out hte retaining clip...or I thought I had. What I had was half a clip. The other half remains in the groove. Corroded firmly in place. It's currently soaking in penetrating fluid before I try and pick it out. Had broken clips before...had rusty clips before. Never had one corroded in place or actually rusted clean through. The alloy, however, was not corroded at all. No fur...just red rust.

When that finally shifts I can have a go at getting the damn fork seal out. I expect another battle...........
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Bryanj on November 08, 2018, 04:37:14 PM
Fork top nut impact hammer with 6 sided socket, seal make sure you do not damage the surface oinside the slider, seen lots of leaks from that. Broken circlip may respond to heat from one of the canister plumbers torches---i use those on the master cylinders to clear out all the crap and make the clip moveable.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on November 08, 2018, 06:27:04 PM
I hear you on the seal ....made that mistake before. Will be popping it in hot water and try to pull the seal....no metal tools trying to pry it out. Will try heat on the clip too....but can't start on the seal until the clip is sorted. I really don't want to damage the groove either.

My impact screwdriver has a socket 1/2" drive thing on it. Will try that.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Bryanj on November 08, 2018, 06:57:11 PM
I was think more of a widy hammer like tyre fitters use on wheels, maybe you can take it to your nearest tyre shop and ask a favour? As to the clip and seal the small torch will not damage the groove just loosen all the crap on the metal and the seal is shot anyway.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on November 10, 2018, 11:51:10 AM
Ha Ha! One step forward. Not all the steps...but I will take 1 step forward and no steps back any day.

The fork cap is off and the other leg is apart. Now, I read somewhere that oil and water don't mix....but it appears the previous owner of this bike had a very good go. What fell out of hte fork legs was an interesting mix of sludge, oil and a bit of water. It didn't mix on my shed floor either.....

Note to self...use a bigger bowl to catch the mess so you don't pour it all next to the bowl....not in it. Still...the shed floor needed a good clean anyway.

Mess cleaned up, the opther clip came out easy and in one piece. I could almost consider putting it back in ...but I won't. Both dust caps were cracked and hard as nails so both will want replacing. They won't keep the dust, grit water or field mice out.

After a gfood soak in WD40, the broken bit of clip popped out nicely. I was able to get a pointy thing under the end and it came out. Wooden cocktail stick for the win! The same stick has got the crud out of the groove aided by the Mk I Fingernail. No pointy screwdrivers here.

(https://i.imgur.com/HLt5SOq.jpg)

So...that's progress!

Neither fork seal will budge a bit, so the next thing to try after an overnight soak will be some heat. Hot air gun should help to expand the alloy a bit and hopefully break the seal and let the seals come out. So far..I have been using a reverse puller just hooked under the seal held in a vice while I try and tap the leg off the seal with a rubber mallet. Not having it....and I don;t want to try force...so will try chemicals...followed by fire. I can think of more drastic things to try...but I REALLY don't want to be doing things like them.

(https://i.imgur.com/R2zbJqK.jpg)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Trigger on November 10, 2018, 11:40:07 PM
I always put them in the oven and the heat will soften the seal to make it so easy to pull out  ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Yoshi823 on November 12, 2018, 05:13:08 PM
Only just had a chance to begin to read about this project. Got as far as the part where the basic part of the bike was carried through the house & it reminds me of the 3rd rebuild of my 750F2 back in the early '80s. At the time I had an upstairs maisonette so there were several flights of stairs to navigate so as to get the frame & engine assembly down to the garage.

This was in my bedroom...

(http://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/Honda%20750/My750037-1.jpg~original)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on November 12, 2018, 06:05:49 PM
Glad I didn;t have to negotiate any stairs!

Have to ask though...that frame...doesn't look standard. Looks like you can actually work on the engine with it in the frame.....
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Yoshi823 on November 12, 2018, 09:57:17 PM
The standard frame was modified so that the top end was able to be worked on, mainly because I had a tacho drive oil seal go & I ended up having to remove the engine just for that 20p (at the time) seal. As I didn't have any of my own facilities at the time, I had to use a friend's garage, much to his mum's annoyance.

(http://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/Honda%20750/My750031.jpg~original)

The modified frame needed a new tank to be made, which wasn't a problem as I wanted a Phil Read Replica style tank

(http://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/Honda%20750/BikesBikesBikes213.jpg~original)
(http://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/Honda%20750/My750042.jpg~original)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on November 18, 2018, 12:36:23 PM
OMFG ..... I feel exhausted...but I AM VICTORIOUS!!!!!!

One by one the last bastions of cruddy fork seals have fallen to the onslaught of my mighty hammer, consigned to whatever foul hell spawned them. The battle was tough, and many were slain, but at last, I stand victorious atop a heap of severed seals.....

well.....I blame that on reading too much Tolkien as a child.

Anyway. The fork seals finally shifted. Much heat from the heatgun was required along with careful application of ultra-violence. A piece of 10mm OD steel tube was found in the spider haunted recesses of the shed, which fitted up the damper bolt hole and located in my smallest 3 leg puller. The pushed against the centre threaded bar and also kept all 3 legs spaced evenly at the right diameter to bear on the seal. This was after I had ripped off the rubber section on the inside to reveal the steel 'ring' and it's flange. ( a much under-used word...flange.... )

I could then beat seven bells out of the end of the steel tube and apply direct pressure on the puller without hte legs trying to close up and slip out of place.

Next...much heat was directed at the area from my hot air gun. Heated to the point the remaining rubber started to stink a bit and things got too hot to touch.

With much hammering, the odd bruised finger and much yelling of 'shift you bugger' ... first one and then the other came out.

What surprised me was the fact that there appeared to be virtually no corrosion of the alloy under the seal, and nothing but age and friction was keeping them in place. Still....that was enough to hold out for slightly longer than the allies held Tobruk in 1941.

With the seals out, I could properly clean up the last remnants of corroded steel stuck from the rusted springs and clean the muck from inside the legs where the sludge collected at the base. They a\re now ready for a quick rub down ( as am I ) followed by a coat of paint.

Not sure if the finish here is supposed to be gloss black...or satin. I am leaning towards satin as i plan on the same finish for the brake calipers and will fit rubber fork gaiters as it fits the look I am going for...and stops stone chips. I had some smart Neoprene ones on a supermoto a few years back. Might see if they are still being made.

Some days...restoration work s a bitch when it won;t work. Other days...simple things just give so much pleasure when you make progress.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: paul G on November 19, 2018, 08:09:34 AM
 yelling of 'shift you bugger'

Never in a million years did you say BUGGER ;D ;D ;D ;)
Keep up the good work.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on December 10, 2018, 08:51:31 PM
Been a struggle to get stuff done over the last few weeks.

I have begun stripping and cleaning grotty old bits of metal and getting stuff ready for paint...but weather has been really impossible for paining. Cold, damp, and unpredictable.
Most of what I have been doing recently has been tidying ..organising...and consolidating.

Need to get Christmas out of the way, and then i can ghet this project back on track.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on January 01, 2019, 04:20:42 PM
Christmas ...and the festive season has been and gone, new year has been and my liver has gone.... so it was shed rehab time.

Didn;t get bought the parts I wanted Santa to bring....but I have some cash to spend, and some kind of a plan formed in my head.

One thing Santa did bring me, bless him, was a small ultrasonic cleaner. Been thinking about getting one for a variety of reasons....and not just to clean the dirty teaspoons.

Ran it for the first time today, and after a few runs through and about 20 minutes of effort, I was pretty pleased with the end results. The one I got was just big enough to take a single carb, and for cleaning up the small odds and ends, and for my other hobby ( RC cars ) this will also be perfect. So...does it work??

before:

(https://imgur.com/dtH1lGf)

carb just fits neatly into the basket

(https://i.imgur.com/oDpLo4E.jpg)

And after a few runs of the beast, we had this:

(https://i.imgur.com/14sZFO6.jpg)

and water that looked...er...like this....

(https://i.imgur.com/IKNPkN7.jpg)

Took a few goes to shift the crud in the floatbowl....but hte less soilidified crud and fuel residue in the carb seems to have shifted really well. I noticed quite a bit of the dirt on the outside didn;t look to shift...but was just lifted off the metal and wiped away with a soft bristle brush. Going to give the outside a buff up and give everything a rinse with some fresh petrol...and it will be time to order a set of carb rebuild kits and finsish them off properly.

For the time and complete lack of effort required....I was pretty impressed with how this thing did it's work!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Green1 on January 01, 2019, 07:50:19 PM
I'm all for cleaning things the easy way.
I hate prep work of any kind as its to much like being at work.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: andy120t on February 21, 2019, 04:22:36 PM
I love the look of the the black 750 - it sort of reminds me of the Harley in Black Rain ... (sorry, I know I'm not making any friends here!)...
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on February 27, 2019, 08:52:39 AM
Right...the weather has risen above 'bloody freezing' in the shed, and we are back in business with the rebuild project.

Not quite at the point where I can start painting stuff....but it is warm enough to do things!

Yesterday, we dug out hte solvol and the front mudguard and polished it back to a respectable state. There are a couple of minor marks, but it actually looks prety good for an old piece of chrome. There is a bit of rust on the inside, but most of it shifted just fine. I don;t want to underseal the inside of the guard, but I will dab on some rust treatment to kill the rust, then give it a coat of clear lacquer to seal and protect it. I left the rubber bobbins in place on the guard as they are a bit 'solid' but not cracked. Taking them out would have ruined them for sure.

I have got myself into the habit of checking if things can be got before I make a mess of them....

Next...I need to order myself a set of gearbox bearings so I can rebuild the cases. The big question now is do I paint the cases together.....or before I rebuild. Much rubbing down to be done to shift those flakiy bits and prep the surface. I suppose I had also better get a gasket set sorted...and from what I read on here...that's another minefield!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Nurse Julie on February 27, 2019, 09:14:19 AM
Paint all cases prior to rebuild. Always looks better and much easier to get in the oven and cure in bits rather than a whole, rebuilt engine  ;D ;D
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on February 27, 2019, 09:28:50 AM
On the underside of the mudguard,  we discussed recently as to how it can be protected.

Oddjob was doing an original to help conserve it,  and ended up with zinc heavy paint as I recall.

I've never thought "underseal" was for protection of metal and to prevent rusting.  It's just to protect the paint from being chipped and breaches occurring in the protection that offers.
Any mild steel on old cars that's just been coated with straight underseal always rusts like hell in my experience.

Most effective appears to be zinc heavy painting,  and maybe something like coated with silver hammerite to give something of a waterproofing in that underside of mudguard area.

Thread is somewhere but couldn't find.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on February 27, 2019, 09:33:17 AM
Found it,  this is the one I was thinking about.

http://www.sohc.co.uk/index.php/topic,17179.msg148069.html#msg148069

 :)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on February 27, 2019, 05:33:13 PM
hmm...that zinc paint looks like it will do the job. Will add it to the ever growing list of things to spend money on :) But I want to preserve the important parts that give the look I want. And that means a nice shiny chrome front guard.

Odd really...as I remember back in the day the fashion was to bin the chrome front guards and fit fibreglass ones with all sorts of horrid aerofoil shapes on them. Then...as the forks now lost the thing that braced them..namely a heavy steel mudguard...they fitted a fork brace.

Mind you...Suzuki ones just used to rust out completely in the centre....

Julie....gotcha on the paint. Damn thing doesn;t fit in the oven....but I have a plan B .....
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Nurse Julie on February 27, 2019, 05:38:17 PM
Not many domestic ovens take a complete CB750/4 engine and none take almost 100kg or whatever it is. All I know is they are bloody, bloody heavy.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on February 27, 2019, 08:12:58 PM
bloody heavy indeed! Last motor I swapped was a Z750 lump, and I did that on my own. Took two of us to carry the CB750 out to the shed. A wrecked motor would make an excellent ship anchor.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Nurse Julie on February 27, 2019, 08:50:51 PM
bloody heavy indeed! Last motor I swapped was a Z750 lump, and I did that on my own. Took two of us to carry the CB750 out to the shed. A wrecked motor would make an excellent ship anchor.
Plenty that we have through here for overhaul HAVE been used as ships anchors !!! It's the Barnacles that give it away  ;D
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on February 28, 2019, 08:42:30 AM
About the front mudguard,  the Honda type usually rust through in that sandwich area above the brace and around the rivets.  normally seen by rust bubbling through the top surface, by which time it's too late.

Maybe worth thinning the paint first and try getting it to run inside that joint with it upside down.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Moorey on February 28, 2019, 09:21:38 AM
I clean off the rust and use old oil. Warm the steel and the oil and it does get under the bracket and into the rolled edges of mudguards hang it up let it drain and give it a wipe and do it once a year.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on February 28, 2019, 09:32:10 AM
Yep...that double skinned brace area was where they all go, not just the Honda ones. You see the upper chrome layer go wrinkly, then crack and flake. Poke it and you can see the tyre.

Good ideas on getting something in there to keep the air/moisture out. I will do that before I wrap it up and put it away for fitting later. Need to send the forks off for chroming and get new seals, dustcaps and clips and get some satin black for the leg lowers. Oh...and some new head bearings. Then the front end is done.

Then I got to strip, clean and paint the swingarm and centrestand. Not sure about the swingarm bushes they feel OK....so will probably leave them.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on March 06, 2019, 04:57:30 PM
No stopping me now ....well...not with those brakes anyway!

Figured I would make a start on the brakes as I need to get the calipers cleaned up ready for paint and I wanted to see what state thigns were in. As the bike arrived last summer, the brakes simply did not work. They were broke.

Popped the top on the master cylinder, and the rubber etc was all pretty good. Unlike the brake fluid. I say fluid...it was JELLY! I have never seen brake fluid do this, and to be honest....I never want to again.

A soak in fresh fluid and a lot of elbow grease cleaned it out, but I soon found out that the seals on the master cylinder were shot. Normally it's a breeze to pop out pistons just by pumping hte lever....but not here. Turned out there was another plug of sludge sitting in the caliper too. You can see it here where it oozed down once the piston was out...

(https://i.imgur.com/ykH0Fa1.jpg)

Other than that, there was not much wrong here. The hoses and seals will all be changed for the simple reason of safety, but the pads were noi more than 50% gone, the sliding pins all did...and there was even grease in there! Small trasce of corrosion inside the caliper, but nothing that won't clean up. Dust seals were good and doing there job and the pistons was spotless.

(https://i.imgur.com/QdGxipA.jpg)

Should all clean up nicely....
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on March 30, 2019, 05:04:26 PM
God knows I should have known ... but a 'simple' job on an old bike just never really ends up being simple.

But...I had a bit of spare time this afternoon, so I thought I would strip down the front master cylinder. I have saved a bit of cash up, and will be ordering a rebuild kit for same, some bits for the front calipers, and the seals/clips for the forks. At some point, I will send the stantions off for rechroming, as I prefer that to buying pattern. Philpotts have done an excellent job on fork legs for me before, and I have seen some pretty thin chrome on pattern replacements in the past.

So...just whip the thang apart, then tidy up the shed as it's got damn messy over the winter... and then I can put my feet up.

Read the book ...and dug out the circlip pliers.

So...step one : Carefully prise out the rubber dust seal.

Nah....it's goosed. Split and crumbly. So it gets ripped out in pieces. Chucked in the bin. There is going to be one in the rebuild kit anyway, which will be fitted when I put it all back together.

Step 2: Remove the circlip that holds the piston in place.

Out with the circlip pliers, which will not fit in the space around the piston. Great. Figure if I push the piston down, it might let me get in there. Carefully clamp the thing in the vice with rags and bits of wood to protect the ally, and push down with a piece of dowel. Which promptly snaps. The piston springs up and squirts a little residual brake fluid in my face just to remind me whose boss here. Out with the angle grinder..... no....not in revenge. A little light modification to the circlip pliers and they fit in where I need them to, and out comes a circlip with a light dusting of gunge, rust, and stuff. Stuff being the technical term I am applying to the jelly the old brake fluid appears to have turned into.

Step 3: Remove the plain washer and slide the piston out.

You wot! The plain washer apprars glued in place, and the piston will slide in and out...but won't actually COME out at all. Whatever black arts were employed to place it there, I have yet to learn the counter spell to have it come out.

Does it just pull out?
Is there something else holding it?

I have studied the parts and the diagrams like a Buddhist priest looking for enlightenment...but in the end, I have just dumped a slug of WD40 in there and left it to soak.

As far as I can see, there is a pair of rubber seals, which fit on the piston, and the piston is held in place by the plain washer....which in turn is locked in by the circlip. So it should be clip out...and the piston ought to have popped loose under pressure from the spring. Hmmmm.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: hairygit on March 30, 2019, 05:39:48 PM
The washer may well have rusted, or electolytically fused itself to the alloy of the master cylinder. If it's rusted, try applying heat to the outside area of the cylinder, being alloy it may expand faster than the steel and loosen it's grip. The easiest option if that doesn't work is one of DSS replica cylinders.

Sent from my X6pro using Tapatalk

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on March 31, 2019, 06:11:42 PM
Heat did the trick....along with a light 'tap' from the other end. Took a fair bit of work to clean the crud and rust residue out of the circlip groove, but it's all intact and the alloy itself has virtually no corrosion. None at all along the important section where the seals move.

Much cleaning up to remove the crystallised brake fluid that filled the space between the seal and the spring.

One rebuild kit to be ordered from DS .... and I am much happier doing that than fitting a replacement part. It will get a coat of satin black, along with the handlebar clamp piece which was black...but had been painted silver.... There is some flaky paint to clean back, but it should look nice when done. Circlip and washer were rusty as hell and went in the bin.

It's no wonder I couldn't push the pistons out easily....the seals were well gone
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on April 07, 2019, 07:09:58 PM
Crowbarred open the wallet...and bought my first round of bits from DS.

Genuine master cylinder rebuild kit, front brake seals and dust boots, plus fork seals, dust covers and clips.

Went for a genuine rebuild kit, which actually costs more than the pattern setup....and twice what the cheap E-bay kits go for. But when it comes to stopping....I don't like to go economy.
Going to get the forks rechromed when I can afford it. Head bearings and a repaint of the yokes comes next. Plus I need to shell out for a set of brake hoses. Refitting 40 year old brake hoses is ....not a good idea.

edited...because I think I miss-typed just about every other word...
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Green1 on April 07, 2019, 07:18:39 PM
I have used a few cheap rebuild kits on a few different bikes and the pattern kits almost always have the wrong size washers.
Other then that there OK.
All the little bits are what drain your wallet.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on April 09, 2019, 04:19:07 PM
Here is the first wallet drain....

(https://i.imgur.com/JNX0XSn.jpg)

But I have a problem.

I put the old and new piston assemblies together, and now I can't work out which is which. Can anyone help me spot which piston assembly is the new and which the old. They look identical...

(https://i.imgur.com/NOnIj9T.jpg)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: haynes66 on April 09, 2019, 04:28:19 PM
always go with the one with patina...
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on May 05, 2019, 09:22:29 PM
Now the weather is less grim again, and I got a free weekend, some work has been done. Well,, once I had refreshed the coolant on the working machine that was...

Well...the less than wonderful satin black paint issues wer eresolved, and hte fork lowers treated to a fresh coat of satin black. This time they look much more how I wanted. Better coverage and better finish.
(https://i.imgur.com/ij10bhb.jpg)

Then I broke out the paint stripper and started on teh frame and other bits. POR15 stripper is the business. Just like paint stripper used to be back in the good old days. Removes paint, varnish..skin...yup. Burns like the devil if you get some on your skin, or..as I did...get some splashed into the gloves you put on to stop getting splashed... oh well.
Really did the job.
(https://i.imgur.com/y85Trzc.jpg)
Still got to do the headstock, but want to make sure I don;t ruin the info plate though. Will get it taped and protected before I go near it. Some surface rust in a few places, but the wire brush and wet and dry took care of the worst of it. I have put a cover coat on the areas I cleaned up to keep corrosion from starting again.The sections I have done look really nice.

While I had the paint stripper out, I thought I would see what state the petrol tank was in under the matt black paint job it had been treated to at some point...

I knew I was going to find filler, as the badge recesses had been filled both sides, so wasn;t surprised to find a blob of filler on both sides. Will grind that out and check what's under before re-doing it. Was pleasanlty surprised to see how little actuial rust there was. A few scabby patches on the flat areas where rust had propagated under the paint, but very little rust on the seams. Underneath is very solid. There is an oily probably once petrol substance in the tank, but no coatings or linings. Still got it's cap security chain too. The only worry is I can't see what has been done with the badge mounts. Whether they were taken off due to damge, or just covered over as a 'de-badge'. Will ind out when I dremel out the old filler.

(https://i.imgur.com/BnBpZoc.jpg)

Interestingly...I found traces of paint under the filler. Shiny black paint that had been lacquered black. I also found evidence of orange at the back corners and roughly where the badges would have been. So....originally...she was black. Or at least the tank was :) Black with the orange stripes looks pretty good...so she may well end up looking that way eventually.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on May 05, 2019, 09:41:11 PM
Decent progress,  frame looks good too.  Encouraging when things come up well after cleaning.

Did you sort out which mastercylinder part was which  ;D
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on May 12, 2019, 03:56:42 PM
Did some more work on the last bits of the frame...and while I was out in the shed...as it was such a nice day today...I thought I would have a dig to see what lurked under the filler.

Now...the filler itself looked to have been put on over the original black/orange paint, but I always worry what lurks beneath. You paint the thing..only to find there was rust under the filler that pops it free, or else the tank had been holed, and a dollop of Araldite used to petrol proof it before hiding it under more epoxy. So I will always rip it of and re-do it after proper preparation.

Both sides of the tank had a big area of filler, so I was expecting dents. Did this once on a Kawasaki tank only to find huge dents on both sides that had reduced the tank volume by nearly a gallon.

Sods law operates well in these events, and predictably the filler was really well attached and showed no signs of budging...so my cheap low power dremel type tool was pressed into service with a burr to grind away the filler. After an afternoon of hard graft, one side is fairly well excavated....and this is what I found:

(https://i.imgur.com/kBk9oK8.jpg)

Looks like the bulk of the filler was just slapped on to de-badge the tank. Not sure if the tank badge fixtures were machine screws or self tappers, but it really does look like it ought to be possible to reinstate proper tank badges. Something I would really like to be able to do. Obviously, I haven't done the other side yet...but having cleaned the filler away from the whole badge recess on one side, I can see there is no damage to the metal around the badge.  Overall...I am really impressed with the state of this petrol tank.

Relief really...as when I saw the bike advertised, it had a red tank on it which lacked a tap and looked scabby...but had badges. The seller told me it wasn't the original tank, and that he had that one as well. I was basically offered the choice. He brought both along and I went with the original tank as it had a tap, the original cap with security chain and looked a lot better inside. It was just painted horridly and lacked badges. Now I have stripped it....I can see it is in really good order, really not rusty, and if I can get the badges back in situ....I will be a happy bunny indeed.

Of course....the other side could be a horror story...but I will get to that in due course!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on May 26, 2019, 04:35:46 PM
Damn.....I am pleased with how this turned out.

After much paint stripping, wire brushing, sanding and wet and dry fettling, the frame was ready for paint. I am not a fan of powder coat, though I do see it's advantages. I also wanted to do this myself, and do as much as I physically could. Now...I do not have pots of cash, so am trying to swap spending for time, effort, and elbow grease when I can. I also am really not on a time schedule and find this project to be as much therapy as anything else. Today was one of those 'happy' days.

The frame was suspended in the middle of the shed with acombination of contrived contraptions and bits of wire and chains. It was solid, and the thing wouldn;t swing. Musn't swing...the shed isn't big enough! There is room to swing a small cat in there...in certain directions....but a full sized moggy won't twirl. Everything else in the shed had to be covered up, and was. The weather was nicer and warm...but not too hot. It was time.

2 cans of smooth black hammerite and a couple of face masks later, the deed was done. The floor was also painted and sticky. Bit like an old pub carpet...everything not covered up was sticky with overspray. The masks clogged...and I had to take regular trips outside to breath.... but I am dead chuffed with the end result.

(https://i.imgur.com/4xQuRXm.jpg)

It is soooo...shiny!

Of course, it's also only touch dry, so I don't dare try and lift it down, and I also want to rig up a stand through the swingarm pivot and engine mounts so it won't rest on soft paint It is OK where it is for now...but I can barely get around it, and it's kind of...in the way...hanging in the mifddle of the little space I have.

Next job, really, should be to get the forks done. While that is happening, I can clean...strip and paint the swingarm. Seems to make sense to build up a basic rolling chassis so the frame doens't sit on it's paintwork and it will make it easier to move about in the shed if I can move the bike too. Happy days.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Nurse Julie on May 26, 2019, 05:42:59 PM
Great job you have done there......ooops, watch your head , don't ruin the paint  :)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: paul G on May 26, 2019, 07:22:03 PM
Looking good keep up the great work and the posts  :)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on May 26, 2019, 08:21:18 PM
Great job, I too like doing things myself and the last time I did a frame I had it hanging on a washing line in the garden, had to wait for a sunny dry day with not a lot of wind. When I painted the smaller parts with rattle cans like you have found out everything in the garage was coated, years later I'm still finding the stuff.

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Laverda Dave on May 26, 2019, 09:35:05 PM
That's a good day's work there. Be careful when you handle the frame as my past experience of using Hammerite is that it stays quite soft for a period of about a week. I painted a workbench and moved it a couple of days later when it was dry only to leave finger marks in the still soft paint! Keep it hanging up for as long as you can before you touch it.
Keep the updates coming, great to read 👍.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on June 01, 2019, 03:49:15 PM
More stuff done, and some progress.....and issues.

Started stripping and cleaning the swingarm and rear brake assmebly. The caliper came apart fairly easily...which was good. The sliding pins were free sliding, which is amazing considering virtually every bike I have ever owned seemed to have siezed them.

But...I think the rear master cylinder is going to give me trouble...
When I took the rubber boot off...

(https://i.imgur.com/8tiNABp.jpg)

hmmm....it's an interesting combination of sand, dirt and rust powder. It's not really useful...and not really helpful in any way. But I have a load of it if anyone wants it....
The rest of the assembly is soaking in WD40, as I can see the ciclip ends...but not budge them. I am expecting there to be some trouble here, and possibly a rebuild kit.....

The swingarm is in pretty good order, with just rust around the ends where the wheel spindle was. I will also really want to replace the rubber bushes for the shock mounts. They are cracked and perished, and I really don;t see them being usable. The other end showed a grease nipple installed. Looked like an original fitting. That's good...

Or would be if it wasn't sheared off.

(https://i.imgur.com/q2P0TyQ.jpg)

Gonna be a bitch to drill that sucker out, but I will give it a shot.

The POR15 paint stripper made short work of the original paint, and it just needs a second going over to remove the few patches the first coating didn;t strip.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on June 01, 2019, 07:43:44 PM
That master cylinder looks pretty much like mine did, lots of fun but they do clean up nicely, I must try and get on with my F2, I feel guilty every time I go out to the garage.

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: UK Pete on June 01, 2019, 08:02:07 PM
Wow you certainly have had your work cut out with this bike, keep up the good work fella

Sent from my SM-G930F using Tapatalk

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on June 01, 2019, 10:17:13 PM
She's not too bad .... It wasn't expensive but was actually pretty complete, and the engine internals were sound. I could just chuck away things like this and replace...but where's the fun in that :)

I want to try and get every bit working as it should, and try and make each piece look as nice as it ever did. Just looking at the smooth and shiny frame paint makes me happy ( is that wierd??? )

I want to try and complete the rebuild without spending more money than the bike is ever going to be worth....so...perhaps the slower I work....the more it will appereciate in value...so the more I can spend...Hmmmm......
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on June 16, 2019, 03:53:16 PM
Gods Holy Trousers..... I give up!

Not on the project...but on a weeks worth of effort to break down the rear master cylinder. It's not happeneing.

The adjuster nuts on the rod are welded together by rust and won;t come off...and the centre section of threads look to made of iron oxide...which isn;t helping.

Worst of all..the circlip simply will not shift. Both ends where the circlip pliers should go snapped off in the struggle, and where I can see the groove....it looks....wrong. The profile should be  |_| .... but its more ... \_/ and the circlip will not move at all. Heat didn't shift it, soaking in penetrating oils/WD40 failed, and I can't even punch the ends and make it move.

I am at the point of drilling into the groove from outside to punch an end free ..... but I don't think that's a good idea. I have run out of other ideas....so I think this part is heading for the scrap pile and the quest is on for a servicable replacement.

So...in order to make myself feel better....I dug out the solvol and started cleaning the comstars. Not that they are bad...the alloy is really unpitted ...but really more because I felt I needed to achieve something!

EDIT:
actually...drilling 2 small holes through the alloy behind the circlip, and whacking it with a drift ( well..actually a snapped off old 1.5mm drill bit ) got the clip. It came out in 2 pieces, but it came out. Now...I have to make the piston move, and it won;t right now. Unlike the front MC, you can't get at the back of the piston to drift it out. There is no 'back' you can get at. So....more WD40 has been poured in through the available holes in the back of the unit, and it will sit for a few days to marinade. ....

And I have had zero like finding a replacement unit ...so this has damn well better work!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on July 13, 2019, 05:13:43 PM
Well...I didn't give up..... I don't think I actually know how :)

I had decided my rear master cylinder was scrap....and that kind of gave me the leeway to get a little bit....er...brutal.

So...I drilled the head off the piston. Cored out the middle and took the head off. This was the bit that had glued itself to the bore with crud and solidified brake fluid.

Got the piston top off...and soaked in some more WD40. Then...using a pair of forceps and a needle...I teased a split into the rubber seal, clamped it and tore the sucket out of there. With that out...the rest of the piston could be pulled out.

(https://i.imgur.com/Tpktxv8.jpg)

The wreckage of the tear down looks pretty sorry for itself....

Now I will see if I can polish the bore to the point where I reckon it can actually seal on a fresh piston/seal. A little irregularity can be taken up by the seal....as long as it's not pitted or scored to ruin a seal of let fluid past. The Solvol will be broken out and I have made up some round polishing mops gluing sponge onto some old sanding tools for the Dremel...so tomorrow...I shall polish and see if I can get a smooth durface. Worth a try! If I can get it smooth and shiny...I will buy a rebuild kit and see if I get pressure.

Victory.... OK...a small one....and not by means I would recommend to anyone.... but a victory none the less!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on July 13, 2019, 06:37:36 PM
Nice one, hopefully it will seal, fingers crossed for you.

Cheers

Dennis

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on September 01, 2019, 11:35:07 AM
Pressures of life...work...and...er..life have been keenly felt of late, and it's slowed progress on the project. As has the trusty daily rider Hornet....picking up two punctures in 2 weeks and needing new rear pads. But she works for a living..so that takes priority.

But...things have been moving slowly. Flushed with success on the rear brake......the swingarm was next on the list in my efforts to get a rolling chassis. Only taken me a year to get this far.....er....yeah.

The actual swingarm p[ivot felt fine when I was tearing the thing down with no real slop or play, so the bushes will stay. The rest was not so good. Much crud had to ber cleaned off, and strangely...one side of the arm was covered with a fair bit of surface corrosion, one was good. The corrosion was chainside....so I suspect Mr Previous Owner wasn't much of a one for chain grease.

The surface prep took a while, but the paint came off easy ( I have some REAL paint stripper... ) the chain guard threads were cleaned up, and a sheared off grease nipple was found on the swingarm. Nice to see Honda put one there....but this one was a goner. Also beyond usable were the rubber bushes for the lower shock mounts.

these had me stumped until I found a brilliant solution...well..I say 'found' ... my brilliant solution was to ask on here....and I got a souiltion that worked well!

I attacked the fossilised rubber with an old and blunt 3mm drill bit, drilling holes through the crumbly rubber around the edge between the inner and outer metal sleeves. This allowed me to pull out the bits in between with what are actually locking forceps I picked up years ago at an auto jumble. Then...I popped a hacksaw blade in and cut through the outer sleeve almost through...then punched in the edge to collapse it. On one I scored slightly through the sleeve....but no harm was done and teh metal on the swingarm was barely marked and not 'grooved'.

Now I can order replacements and press them in when the paint has had a few weeks to harden.

(https://i.imgur.com/wc8iPg1.jpg)

Happy days.

Oh...yeah...one fly in the ointment though...well actually...fly in the damn paint! Sprayed it on the washing line as it was a nice day. Then carried it into teh shed to keep it away from flies, dust or the chance of rain. Hung up in shed and I see a damn midge buzz past and settle on the fresh, tacky paint. Well...I know better than to try and sort that now....so midge is doomed, and I will have to flat that back later. It's on the underside....so no big deal. Just bugs me .......
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on September 01, 2019, 01:33:21 PM
Nice to see a plan come together

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on September 08, 2019, 01:08:05 PM
No stopping me know...er...well...until I had to stop anyway.

Swingarm painted...

(https://i.imgur.com/8LMmjoj.jpg)

and then did the battery box and torque arm.

Battery box was in a rusty state at the bottom, and needed much sanding and prep to be paintable. Battery acid leaks and general neglect means corrosion is common. Tehy are also very fiddly to sand, with bits everywhere.

Need to order my shock bushings and I can put together the swingarm with the worn out old FVQ shocks going in for temporary. They will be replaced with modern/new units.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Crispy on September 09, 2019, 09:16:42 AM
Just sat and read your story from start to finish, great read you should write a book! I can identify with a lot of your experiences, the highs and lows, master cylinders  >:(  and getting a lot of pleasure from simple things like transforming some part with a bit of paint or succeeding in doing something that you've never done before. Good luck with the rest of the rebuild and I'm looking forward to reading the next chapter!  ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on September 09, 2019, 05:55:42 PM
Appreciate the comments :)

This is part resto...part therapy for me. Documenting the steps and the experiences is fun, and when it's all done, I can put it all together with the receipts and the pictures, and if I ever sell this thing...it will come with a story!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on December 21, 2019, 11:15:18 AM
WEll...work has been taking a toll, along with the other nasty bits of real life...but the project still crawls along and I haven't lost interest.

The Mrs has given me a Christmas gift of a fork re-chrome .... so those weill be going off to Philpotts for a dose of their hard chrome. They aren't really that bad...but...small bits of pitting wherer you don;t want them are unsightly. The swept area was OK, but as it's all apart and I have fresh seals, dust covers and clips...and freshly painted legs and yokes ( satin blacked before the weather turned too cold to paint stuff in the shed! ) seems wrong to put them together with scabby forks.

I also want to use old-school fork gaiters. Fits with the look I am going for, and the blacked motor... But as the last pair of gaiters I fitted were some slick looking neoprene tubes...I might do that again.

The reluctant front brake piston has been popped out, and the front calipers are stripped ready for paint in the spring. New seals were bought...and the pistons are both in good order so will just get a clean up.

The rear brake piston seems glued in. It's soaking right now...and tif that doesn't free it..heat will be applied. I can see corrosion around the edge of the piston where it peeps out...so I am expecting the piston to be scrap. The rear brake on this bike was in poor shape all round...so that's no surprise. A rear brake rebuild kit was on the Christmas list, but I will be adding seals and probably a piston.

One of my 'goals' with the project has been to re-use as much of the bike as wqas physically possible. The urge to throw stuff away and replace is easy to give in to...but I don;t want to. I have time, I have patience...and I want to learn and practice skills, excercising my hands not the wallet....but when it comes to basic safety stuff...I need things to be right.

Next thing to think about is wheel bearings. The wheels are really clean and had no sign of corrosion or furring on the alloy. So...with the forks done, a rolling chassis just needs a few more odds and ends and I am there. Springtime.....will be engine time!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on December 21, 2019, 12:31:45 PM
Your approach sounds pretty sensible to me, I can remember spending a lot of time with Brillo pads, lolly sticks and my little Dremel, cleaning and polishing stuff. It took time but meant a lot of original parts were re used rather than being replaced.

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on January 12, 2020, 07:20:00 PM
Birthday last week....and some pressies were received to help with the project.

I now have my suspension bushes to fit....a rebuild kit for the rear master cylinder and if I could actually get teh piston to shift from the rear caliper....I could paint that sucker too....but it is stuck tighter than a tight thing. Gonna take some time to shift that one.

Also finally got a satin paint finish on the fork yokes that I could live with. The pile of 'finished' parts is growing steadily....

Next job really is to swap the wheel bearings. That means undoing the bearing reatiners....so I sense more fun. The bearings are probably OK...but... having felt the difference when I swapped out the wheel bearings on the Hornet, I want new bearings. What's the best way of attacking the wheel bearing thing?
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Bryanj on January 12, 2020, 08:29:19 PM
For the calipertake the fitting off the flexible pipe on a greas gun and the pipe will then screw into thehydraulic pipe fitting about 1 1/2 threads then pump out the piston. Messy to clean up but its always worked for me
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Bryanj on January 12, 2020, 08:40:18 PM
Look carfully at the screwed in bearing retainers and find the "stake" marks, carefully drill these out with a 3mm drill to about 6mm deep. Warm up the hubs and the retainers should unscrew. 500 rear retainer is LH thread but cant remember on 750
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Moorey on January 12, 2020, 09:09:23 PM
I find it far easier to fasten whatever I am using to remove the retainers in a vice and sit the wheel on top and turn the wheel to remove the retainers. You must drill out the pop marks as Bryan says or you will destroy the retainers.
 
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on January 12, 2020, 09:20:12 PM
thanks guys...that's good to know. I will make sure I drill before I start.

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on February 08, 2020, 11:00:14 AM
Like a glacier.....I roll forwards, but not always at a pace. Life, work, time and money are all things that I have either too little, too much, or whichever 'too' I don;t want..... but we are getting there nicely. And every bit I get done so far, I am happy with, and have done as well as I reckon I could...and I am proud of it. All my own work that. I did that. Me.

But ramblings aside...

Birthday gifts were received, which included a set of rear shock bushes and a set of TEC shocks.....

(https://i.imgur.com/AUY4V4h.jpg)

A slight mix up with the shock order was swiftly rectified by TEC ( must say.,..their customer service was really good. No messing about and problem sorted double quick. Highly recommended in my book ) and this morning was started with a quick shed session. Shock bushes were pressed into the swingarm nice and easy with the old large shock washers making a lovely surface to press on the outers.... and they went in far easier than the old ones came out....

Swingarm was greased up, the old end caps popped back on ( they are still good and fit snugly on the end ) and the swing arm eased into place. Shocks dropped on neatly, and lined up just right. The instructions suggest I give the shocks a workout to settle them, which I will do later, but with the frame propped up as it is...I don't want to. Once the front end is all together...it's going to be a lot more stable!

(https://i.imgur.com/JJPhJfe.jpg)

Next job is to fit the new head bearings. Required a bit of puzzling to figure out which way up each bit was meant to go, but the old rubber dust seal and shim/washer were in the jar labelled 'steering stuff' ... so perhaps I am more organised than I give myself credit for. The lower shock bolts were left in the original FVQ shocks for safe keeping. I have not got a clue where the hell the old shocks are though....doubtless in a 'safe' place.

(https://i.imgur.com/x4gC3w0.jpg)

With this lot all together, the next job is the forks.

Got a holiday to pay for first, but once that's done and funds are available again, I will be sending the fork legs off to Philpotts for a dose of their chrome. I would much rather refinish the original forks than just replace the things. Though...in all honesty, the forks are not 'bad' and would have no issues passing an MOT if I reused them as is...I just don't like pitted forks. New seals, dust covers and circlips are already in the spares box. The lower legs have been painted in fresh satin black....and while I haven't tackled the wheel bearings yet...with the forks done, I have a rolling chassis...so they will be popped in for the time being.

I now need to work out what I am going to do about the rusty chain adjuster block. One side is OK...one side is nasty.


edit: just for the record...total parts spend so far is around £250 ... plus a couple of cans of paint I already had. That includes the front and rear master cylinder rebuild kits and the front brake seals and dust covers. Rear caliper still refuses to budge. Heat required...a job for tomorrow ( Mrs will be out...oven will be free ;) ) so a rebuild kit and probably a new piston there. Was expecting a total outlay around the £3500 mark ... so £1100 for the bike, and hopefully a chassis rebuild not busting £750 with brake lines etc and bodywork....I still have around £1500 in the imaginary kitty to put the engine together. The aim is to have a bike at the end which I can use....enjoy...and have it worth what it cost me.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: paul G on February 08, 2020, 11:05:41 AM
Coming on mate slowly but surely  ;D philpots do a great job you won’t be disappointed
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on February 08, 2020, 02:17:11 PM
That's coming along nicely, my F2 is still waiting for me to find all the parts that I stashed in the loft or in the garages when I cleared out the garage to work on the grandson's Moto X bike.

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on February 09, 2020, 02:41:20 PM
Thankjs guys :) I'm really enjoying the process
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on March 29, 2020, 12:28:31 PM
Baby steps....and supply issues....and all the other nastiness around right now, but some shed time has been found as 'self isolation' of the best kind!

Split down the front wheel to get the discs off ready to clean up and paint, and so I can get the wheel looking nice. It's in pretty good order with just a minor mark on the outer edge  and a few light scrathes that will polish out easy enough. The 'spokes' on the Comstars are virtually rust free and will Solvol nicely. No polishing here....just nice and clean.

Getting the spindle out would have been easier if I had loosened the damn nut while the forks were still together and on the bike......  :o

Nut came undone without too much brute force, but the spindle was in need of some WD40 where it has solidified gunk holding it in the spacer. Tea break while it soaked...and it came loose.

Speedo drive had some solidified traces of yellow grease....but worked fine. No sign of worn or damaged gears, so a good greasing and back together.

Discs came off easy...was surprised to see them bolted through the hub, rather than threaded into each side. Pleasantly surprised....as it meant they came off easy. When I have had to remove doiscs on more modern machinery, it has been allen bolts into alloy with threadlock. Not always the best combo....and if you round a head out....it's not fun. For some reason...ther ewas sand in the spaces in the hub behind the discs.... no idea what's gone on there!

Going to wait for the current crisis to wind down bedfore I send the forks off to be rechromed.... but with the yokes ready, the wheel done bar the bearings ( A job I am putting off till later..... cowardice I know.... ) and all the bits to reassemble the forks already bought.... I can almost smell a rolling chassis.

Oh.,...but there was one fly in the ointment...

The rear caliper is FUBAR in all probability.

I simply cannot budge the piston. Not in/out or round. I can see corrosion on the exposed part of the piston. Far worse than the fronts...so that was going to go in the bin anyway. Heat...nothing. Clamped the mole grips on the piston to try and wiggle it round to work it out...won;t move. When I was looking for a master cyliner, E-Bay threw up loads of calipers...but no MC's. Now I want an rear caliper....not one on E-Bay. Oh well...I guess people are not listing stuff right now so they don;t have to go out and post it.... understandable. 

But hey.....still got plenty of things to keep me busy. At some point I got to clean the hideous mess off the back wheel.....
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Bryanj on March 29, 2020, 01:23:16 PM
Put the caliper back together if you have split it, fit and tighten bleed nipple, get a grease gun, preferably eith flexi pipe, and remove the nipple end from the pipe. This will now screw into the pipe fitting on the caliper but only 1 1/2 to 2 turns as its a different pitch. Now pump the grease gun and watch the pistons move, one will move first and you will need to put som thick steel where the disc would go(flat tyre lever) to stop it popping out then the second one will move. When both touch the steel remove the greas gun and steel, split the caliper and you should get the pistons out now.

Then the grotty bit!! You have to get all the grease out of the caliper body.

EDIT

Those instructions are for F1, the F2 has only one piston so just screw grease gun into pipe hole and pump.

You can post it to me if you wish, i never yet failed to get a piston out!!!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on March 29, 2020, 01:52:48 PM
Rear is only a single piston caliper...so the casting is a one piece deal. Seems to me like a downgrade step from F1 to F2 ... presumably it was cheaper and easier to make?

If I can't get the thing out in the next few days I will happily take up your kind offer. I want to save what I can. The jaw marks in the piston are mine....but as far as I am concerned, piston and seals will be replaced. Reusing and refurbing is all well and good....but I actually want the brakes to work as well as 40 year old brakes should :)



Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Bryanj on March 29, 2020, 02:21:24 PM
Single sided piston  pistons move farther so sieze less(in theory) but they need sliders which sieze as well!!!!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on May 17, 2020, 01:12:36 PM
ahh....nothing slows progress like not being able to get stuff in a pandemic.... but we do what we can, becuase it helps stay sane!

So...I decided it was high time I sorted out the petrol tank properly. I had made a start and got the paint off....but had found 2 large plugs of filler..one on each side.

Initial investigations showed nothing underneath to worry about, and so I bagged it and did other things.

So...having ruled out heat and chemical appraoches for filler removal, I hit the stuff with the old Black and Decker and a wire wheel. Heat and fuel tanks is not something I like mixing. doubt very much there is any fuel vapour left in there, but I still worry about distortion. Chemicals...well...can't get a stripping compound that works through available retail outlets.

So...much dust later ( improvised mask was not that effective...so I will probably now die of some obscure Victorian mining disease.... ) but the stuff is off both sides. Tank actually looks pretty damn clean for a 42 year old petrol tank. There is one tiny ding about hte size of a penny, which hadn't been filled....

What has clearly happened is the previous owner decided Honda badges just didn;t fit with the Outlaw matt-black look he wanted, so he binned them and filled the mounts with a metric tonne of Bondo. Removing....I find the badge mounts still in place, the badge recesses pristine with remnants of shiny paint...and I even managed to tease the bits of filler out from behind hte badge screw mounts. Small zip-ties make good 'filler saws' and don;t bend or damage the metal.

Which leads me to a question....

The badges screw onto the tank, and I see the 2 holes each side in the spot welded on bar in the bagde recess. In each hole is a flimsy, thin metal insert. All 4 seem to be there...and I assume these provide an 'edge' for a machine screw to bit on and screw in.

Can these be replaced?

I haven't tried putting any screws in yet, as I need to find out what size they are meant to be...but I assume this is in place of trying to tap a thread into thin metal. Back in the day...I would guess the 'self tapper' would have been the answer...but that would wreck the inserts and potentially widen the holes.

Whats's the best way to deal with that?
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on May 20, 2020, 04:23:08 PM
The reckless spending continues.....not to happen.

But...I now have a left hand side panel to cover the space that was previously vacant.

Bought from LPM, ordered at the weekend, and on my doorstep by Wednesday. Can't argue with that.

I also can;t argue with the quality. Compared to the stock panel on the other side, it is thicker, weightier, and has a lot more supporting the lugs and areas where a lot of the 'used' examples I have seen had cracked. Consdiering I was seeing genuine but damaged panels fetching £80-£90 in teh wrong colours and in need not just of repair...but paint too. And lacking badges.... the cost of the LPM panel is a steal.

Good quality...good service...good price.

wouldn't hesitate to recommend them to anyone looking for pattern panels
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Bryanj on May 20, 2020, 08:29:29 PM
Also more flexible than original
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on May 27, 2020, 12:32:51 PM
Finished the tank cleanup, and the tap is even servicable....aside from needing a new seal between it and the tank. No filters on the tap......so an inline filter will be required.

Very happy with the state of hte metal. Total of 3 very small dents to fix. Lots of good steel.

(https://i.imgur.com/jZzOSa0.jpg)

As the tank will be black, gave the underside a coat of smooth hammerite. Need to makle sure it is fully cured before petrol gets near it...as I know what happens otherwise. But it will help prevent corrosion where you can;t see it or clean it.

(https://i.imgur.com/V0bjofm.jpg)

New set of tank rubbers and badge clips coming from DSS, and when I get some more primer and rust treatment...I will give the tank a basic black rattle can job.

Having to make some serious design decisions now though. Do I go for a stock style seat and bars....or do I go for drops and a single seat for that cafe reacer vibe.
Maybe something like this....
http://www.meadspeed.com/resources/meadspeed/media-files/products/honda/cr750/seat/no-cut-out/main.jpg
as the one thing I will NOT be doing is chopping the frame rails

If I had a stock seat already, I would just go that route. But my project came with a hideous US 'chopper' seat and high bars with oddly angled ends that put your wrists at a silly angle.

Fork legs going off to Philpotts shortly... and teh search is on for replacement chain adjuster blocks. The pieces that fit into the end of hte swingarm. One is fine...the other is corroded to hell and pitted badly. I can smell a rolling chassis in the not too distant future
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on May 27, 2020, 03:57:16 PM
It's good you've a decent tank out of it after the stripping etc.

Looks are obviously personal,  but I think they do look good with the std seat cowl on them with the light lifted up and more inside the housing,  plus a shorter rear mudguard.  Bit more of a "california" look to it.

Slightly flatter bars and a bit wider,  more like an American superbike type look with an inch or so longer shocks to give it that production racer stance.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on May 27, 2020, 04:31:43 PM
Yeah, I can see where you are going with that :)

I have the tailpiece and light etc. and while they are not perfect...it should be repairable. There is a bit of the side trim damaged on one side, but it's by no means beyond saving.
Interesting suggestion :)

Got a few weeks while the forks get done to ponder ideas. Once I got them rebuilt, I can throw the wheels in and actually sit on it and play with ideas a bit more
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on May 27, 2020, 05:43:08 PM
https://www.pinterest.co.uk/pin/627689266785911080/

I had a picture I'd stored but temporarily can't find it to post directly,  but the first one in the above link is the bike I was thinking of.

Really neat interpretation of the original Honda design that just looks very crisp  :D
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on May 27, 2020, 06:05:00 PM
Now that does look tidy. I've dug out the tailpiece I have, and will have a look at repairing it. There is some plastic missing from the rear edge in the corner...but the trim that's damaged has beewn removed in those pics.

I even like the colour...well....it looks the same colour my Hornet is. Corbin seat.... find a rear light that fits in there neatly...yes....I can see that working

Ironically....I found another pic of the exact same bike.... with my initial idea done to one that is parked next to it.

http://i295.photobucket.com/albums/mm127/tweakin_photo/2cbs.jpg

So I can make a direct comparison!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on May 29, 2020, 03:57:31 PM
 
[attachimg=1]

Here's another I was thinking of, it's in a build thread over on USA sohc site.

It just seems that Honda almost wasted the style of the F1 andF2 in UK guise as they seem to droop downward at the rear and suck the "sport" element out of them.

The one above,  to me at least,  appears to make the most of a really good tank and tail shape.

Did you see the program "goblin works garage " in which he did a bespoke seat by using a black yoga mat foam,  glued it in a stack to to layer it up,  then sculpted it with a very rough emery wheel on a hand grinder. 
Pretty effective way of building up a seat foam shape onto original base of your own design with very little cost.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on May 29, 2020, 08:13:29 PM
yeah...saw that. Have done it before myself.... used one of those closed cell mats for camping. Then covered it in flat vinyl.
Would have worked far better if the vinyl hadn't been that shiny...
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on May 30, 2020, 11:17:06 AM
Some more bits and pieces :)

Money is a bit on the short side in the current climate...but small steps. Ordered Thursday...arrived today. Pretty rapid service from Dave Silvers.

(https://i.imgur.com/bX9Ezb3.jpg)

Rubber mounts for the fuel tank, a fresh sealing washer for the fuel cap ( mine is a bit cracked....and probably won;t seal well ) and 4 fresh clips for the tank badges. Having seen the sort of money they fetch when they are for sale...I don;t want mine falling off when I finally find some.

The things are not threaded inserts or anything fancy...just clips that locate in the tank and grip a plain pastic shaft. I would suspect the badges on mine wer enot carefully removed before the recesses were filled in, and these sort of fastening tend to be single use only.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on June 20, 2020, 11:10:55 AM
Now...for some....a great occasion is that first startup, or getting the engione in the frame without loosing fingers, paint, temper or all of hte above.

Today, though, was a great occasion for me.

After far too many weeks of trying, or sweating, swearing, and blood sacrifices in the dark of the moon..... I GOT THE REAR BRAKE PISTON OUT!

so what, I hear you cry......but you weren't there man, you weren't there during the dark times.


(https://i.imgur.com/HxtN205.jpg)


Some interesting crud came out too, and the piston was not usable before I chewed it with molegrips .... but I was expecting a rebuild to be required.

How did we do this. We went primitive.

(https://i.imgur.com/sIz4ux4.jpg)

Fire. It kept us safe from wild beasts at the dawn of time, it made our food easier to digest, and it gave us warmth against the cold of winter. It also does a number on the seals, sweating them to the point where the rebuilt front MC I had hooked up could budge it. Until it cooled...whereupon it locked rigid again. FIRE! and it was out.
Bit of a mess to clean out, and I managed to ruin the paint on the MC spilling brake fluid on it, but a small price to pay.

Lumps of what I assume are fine grit or sand, mixed with solidified brake fluid were lurking in the back, along with a congealed spider nest. I suspect this caliper spent some time sitting with the hoses off.....or else the guy lived in a dusty place and took no care at all when topping up the fluid. But spiders?

(https://i.imgur.com/nU2OeHp.jpg)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: woody928 on June 20, 2020, 12:59:58 PM
I've just taken the long read of this epic journey, what an adventure you're on!

I do admire your enthusiasm and sense of humour through the difficult times and battles with stubborn parts. It looks like you're making some amazing progress. It's giving me some great and no so great ideas of what to expect along the way!

Keep it up, I'm glad to see that fire is still las relevant today as it was a couple of thousand years ago!  ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on June 20, 2020, 02:12:35 PM
It's a great sense of achievement when something like that happens, mixed with relief

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on June 20, 2020, 08:46:17 PM
I am really enjoying putting this thing together, and this thread is kind of like a rebuild journal for me....as well as ( I hope ) an entertaining read.

I set myself the goal of doing this on minimal money, but also saving and reusing as much of the original as I possibly could. I could buy loads of parts and do it far quicker....but...then I would miss half the fun, would have to spend a load of money I don;t have...and...well....when I was done....I would probably have to go buy another wreck and start all over!

Maybe when I get a garage ;)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on July 31, 2020, 06:05:37 PM
Happy days :)

Forks are back from Philpotts and I can put them back together again and get a rolling chassis together at long last. Will make things easier in the shed as I will be able to move the thing about a bit!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on August 01, 2020, 12:10:31 PM
After initial paranoia about the forks and the fit, it's another excellent job by Philpotts. Threads all perfect and nicely fitting and everything dimensionally perfect.

So, with the forks here, it was time to build them up.

First task was to find the other parts, the fork lowers were easy, and the springs/dampers had all been carefully threaded onto wire loops and wrapped in rags so all the bits were in the right order. The fork springs didn't look like they were wound differently...but I still wanted to make sure they went back the same way round they came out. I wasted 5 minutes looking for some shims to go on top of the seals between the spring clips...until I checked the parts list...and these don't have them. Which explained why I couldn;t locate any. Most forks I have rebuilt have...or is it just a Kawasaki thing?

Anyway.....

(https://i.imgur.com/WJKQPiX.jpg)

So, found a lovely large impact socket for a drift ( no I dea what I bought it for...but it fitted something somewhere that I really needed..... ) and tapped in the seals. The well for the seals was deeper than the seals themselves.....so I tapped them in to just below the clip groove, and measured both to make sure they were the same. I wanted them to sit just under the clip and in line with the lower edge of the groove. I figured if I was meant to tap them all the way in....I could always go back and do it....but getting the seals out would probably mean mean new seals..... Having once fitted one upside down....I found out the hard way that just about every tool capable of loosening the grip of a seal wrecks it.

(https://i.imgur.com/hLo1wZj.jpg)

New clips went in easy. The old clips came out in pieces....

A little wipe of oil on the seals, dampers inserted...and the legs slid home sweetly. Dust caps were gently tapped home with a rubber mallet, and the process repeated for the second leg.

Now...to tighten up the damper bolts I need to compress the springs and screw in the caps. Then it's easy to nip up the damper bolt. Don;t want to fit the legs until I can drop the wheels in...and that really wants the dampers done up. Not sure if new copper washers are necessary...but I gave mine an anneal on the stove and will see if they are oil tight. They didn;t look dished or distorted....but if I need to, it will be done.

(https://i.imgur.com/YZGsCJA.jpg)

So just fill up with the right fork oil ....er..... fork oil. You did buy some fork oil right? Bother.

So...when I buy some fork oil, I will finish this off and pop the front wheel back in. Any recommendation on fork oils? Book says 10w .....

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on August 01, 2020, 01:25:20 PM
Nice work there,  always good to build up things with well prepared components too.

I'm using Motul fork oil across different types of fork as it works well, bought via internet for availability and price. Mostly use 7.5 viscosity.

Auto transmission fluid is fine though,  but ordinarily rated at 5 viscosity which may feel a bit thin on this bike.  Certainly wouldn't initially go above 10 viscosity unless you identified genuine need as that usually stiffens them too much and they "bob" rather than move in a more supple way over stutter bumps.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on August 01, 2020, 02:56:29 PM
Looks good, it's really nice to put things together with all the nice bits to hand, certainly better than bashing them apart.

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on September 17, 2020, 06:40:11 PM
Well...the project is on a bit of a hiatus, as I am trying to move house...and that is a thing of terror.

On the plus side...one of hte reasons I wantr to move house is because I have a small and overcrowded shed, with no access to the road. So if I build hte bike were it is....well...it would have to come aparrt again and be carried through the house!

The new place which I hope to buy (offer accepted....and same on my current place) has a garage. A proper one. All the space I will ever need. It's a super-mancave, and is this mans dream setup.
The bikes will have a dry and secure place to live, and there is even a house attached to the garage for the mrs.

If all goes well, progress will go a lot smoother as I will have room to spare!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on September 17, 2020, 07:09:33 PM
Good luck with the house move, a very stressful time, I recently narrowly avoided it by building an extension to give me more garage space and spent some more on the garden for the "Boss".

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on June 14, 2021, 10:21:29 AM
Yes!

this project isn't dead, and can now ..after 9 long gruelling months of trying to move house, finally get back under way.

Next week I get the keys to the new place, and it has a garage! the space I need to start assembling the beast. Before, all I had was a shed in the back garden with no access to the road..meaning aything I put together woud have to be carried through the house and assembled in the front garden. Not an ideal thing, and after that, it would have to live under a cover in the garden like my working bike does. Not the best setup either. Now I will have both the space and the storage.

Moving is going to be a bit of an upheaval, but once I am settled in, it will allow me to take stock of my stuff, lay stuff out, and start putting together the bits I have. There will be some bits that have suffered in storage ( I know I chipped hte frame paint....aaargh!) but I am so looking forward to getting established and getting this project back n the road now I have the space I need to enjoy it :)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Nurse Julie on June 14, 2021, 10:45:56 AM
Good luck with the move.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on July 31, 2021, 05:08:20 PM
Well....I love my new garage! All the hassle of moving, boxing stuff up, unboxing stuff, and not knowing what is where is fading, and I have got some quality time in the bike space!

Ordered some parts from DS to get me going. Got a full engine gasket set ( which isn't... as it has no head gasket) and an oil seal set as I work my way towards getting the motor back together. Just need a load of gearbox bearings and a new primary chain and tensioner before I put hte bottom half together.

I also got myself a set of head bearings. I wanted the genuine Honda ones...but no stock, so I bought taper roller. I had bought a set before ...but they simply were a rubbish fit. The adjuster castle nut would barely get on the first thread, let alone do up. So....it was with a small degree of trepidation that I bought another set...and set to this morning.

The bearing sets went into the headstock with no dramas, the old bearing seats providing a handy drift to settle them in snug. Before I started though, I knocked out the set I had tried to fit....and put the stacks in order next to each other.....hmmm...

(https://i.imgur.com/lf3b5gk.jpg)

Can anyone see an issue here..... the newer set from DS is on the right..

They came with a spacer, and no instructions....but when I offered up the stem it was clear that the spacer was needed on the lower bearing, to let the lower yoke clear the headstock, and as it also placed the lockstops dead centre....it was obvious I needed it. The spacer needed a bit of dressing to slide on smoothly, and then I could pack the bearings....drift the lower race into place, and it all screwed up together just perfect.

It's at this point, that were I an engineer of Alan Millyard's calibre...I would have had time and opportunity for a cupcake. But...the Mrs doesn't bake anything humans can eat so I just got on with some more stuff.... Lucky bugger gets to be a genius and gets cupcakes.

Anyway...with the steering parts in place, and the hideous bars it came with bolted up for convenience....I thought I would drop the forks in. I know the top yoke has to come off again for the headlamp, and a few other jobs....but I wanted to get it all together for an initial build to make sure I had everything, and to make sure I found any snags. All went swimmingly!

(https://i.imgur.com/KKBBdiW.jpg)

I dusted off the wheels, front and rear, and got them into place, mainly so I could get the thing up on it's wheels to make it easier to move about. Things like the rear wheel spindle, spacers and the adjsuter end blocks are all a bit tatty....so I might invest in a plating kit to re-do these parts. Not sure how cost effective it is...but...it just might be a fun thing to try and do.

As a last vanity act....I just dropped the tank onto the mounts.....

(https://i.imgur.com/9Vscp4D.jpg)

Reminded me why I wanted to own one of these in the first place. Lovely clean lines.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: philward on July 31, 2021, 05:58:36 PM
Good work and looking good!

Sent from my moto g(7) power using Tapatalk

Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on July 31, 2021, 07:22:29 PM
It's nice when you can actually see something to justify the hard work that you have put in.

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on July 31, 2021, 09:22:45 PM
Good progress and always gives encouragement when you can see a rolling chassis too.

Garage looks good too, is that a work pit in centre covered by planks? 

The taper head set you can tighten them to about 30 lbs torque to fully set everything while swivelling them to help the rollers seat the assembly.  Then undo and finally tighten to  5 lbs for good running loading.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on July 31, 2021, 09:36:18 PM
It is indeed a work pit :)

I've gone from a tiny shed in the back garden......to a palace of a garage, with a separate workshop area.
I can finally have my tools like this:
(https://i.imgur.com/1uH2oLs.jpg)
and I can find stuff!

Top yoke will have to come off again for headlamp/clock assembly.... I'll set it properly then. Process noted for when I do :)

Brakes are next. Need a new piston and seal for the rear...but have new parts for the fronts. Need some high temp paint for the calipers first. I also noticed the frame has a few marks from storage/moving that I need to fix on the lower rails. Annoying...but I should be able to blend it in
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Johnny4428 on July 31, 2021, 09:39:44 PM
Looks good! I must admit I am forgotten what a tidy workshop looks like! Maybe Monday.😂
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on August 01, 2021, 10:54:57 AM
That garage/workshop looks great, I will have to sort mine out, it started off neat but is a mess now.

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on September 02, 2021, 10:01:21 PM
Only been able to do a few small things, but some major decisions await that could affect teh whole direction the project takes......so I got some serious deciding to do...

Today, though, I decided to try and sort out my poor old exhaust headers. They are not in bad shape...but where the join to the silencer sits....corrosion had set in. The back end of the pipe was a wreck. BIG hole blown out and the thing was rotten as an old pear. But the headers were nopt so bad. When I took off the clamp and chiselled off the crusty gasket...I found a chunk of the surface under the gasket was ......not metal anymore.

It was quite localised, with an area the size of a postage stamp gone.... so I figured I would have a go at fixing it.

I cut out the bit that looked bad....only to find I needed to cut out about 4 times that to find metal that wasn't too thin. It's bad enough trying not to blow holes in sheet metal without it being so thin you can poke holes in it with your finger....

Found a bit of scrap steel the right thickness....and spent a while shaping it. Got it perfect roundness...then realised it's only round at the end...and had to 'unround' it to fit right.

Fired up the old MIG welder....and then spent a while grinding it back and making it nice. Found the pinholes I had missed....filled them...ground back again... Quite pleased with the end result. Well..on the outside. It's not so nice on the inside, but there isn't a whole lot I can do about that. Its solid though, which was the thing I needed.

(https://i.imgur.com/KcQF96X.jpg)

My problem now, though, is how to proceed. It was always my intention to go mildly cafe-racer on this, but the question now is how far to go down that route. The only rule here is I will not cut,slice or ruin anything Mr Honda made....but the seat is in the bin ( it was too far gone to save and not a genuine part anyway ). The exhaust is toast at the back. I also have some issues with the brakes.

The rear brake has issues with the master cylinder and reservoir...and the actuating rod. It also has a shot piston and needs new seals, dust caps and hose. I have cleaned a LOT of corrosion out of the master cylinder...and don;t know if it will actually hold pressure. Trying to find a decent replacement has not turned up anything that looks any better than mine...and some that look much worse. The fronts need hoses and new pistons....but at least the rest is OK. Need to read up on the seals...as they don;t look directional...but I want to be sure before I put them in!

I had a glimmer of hope when I was told that the brakes off a later CB750F/900F could be used with the brackets and give me twin piston calipers....yeah. They are rarer than the hens teeth I am already looking for. So that was a no

plan a) rebuild rear master cylinder and hope!

plan b) use a non standard replacement master cylinder. This will involve making a new bracket, which is no big issue, but I have no idea how to select a suitable replacement. Ideally I would want one that shared the same hose connections...so I can buy a proper hose...and be able to fit it.

Plan b) is where things get complex though.....as if I am making brackets....I could get some ally and make footrest brackets to fit rearsets....which leads into exhausts.....

I simply cannot find a set of exhausts I like. The Delkevic straight pipe system looks OK...but I do not like the lines under the engine not being horizontal. I could get my headers rechromed....if I can ever get the damn things apart ( one header out....one not shifting!) and fit a replacement silencer....but it's not convincing me. The only setup I went YES! at was a custom setrup on a KZ....which would mean having it made. But..if I am making custom footrest hangers.....

Just got no idea how to find a compatable master cylinder.

Oh well....time to drink beer and ponder. Usually works
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: McCabe-Thiele (Ted) on September 02, 2021, 10:54:30 PM
Thinking of your exhuast system particularly the manifold pipes -  how about having them all made in stainless steel?

About 20 years ago the front pipe on our Merc a W124 260E was very badly corroded due to the PO visiting building sites so cement slurry rotted a lot of underbody parts.
A new MB front pipe was daft money - over £500.
A firm in Huthwait, Notts http://www.stainless-exhaust.com/ basically made a replica manifold a 6 into 1 system. I've just looked it up my manifold cost me £200 in 1999 - including fittting.

There is a similar firm called PD Gough who build similar systems they are in Watnall & have a website https://www.google.com/search?q=pd+gough&rlz=1C1CHBF_en-GBGB934GB935&sxsrf=AOaemvKCWX7C9DfnQgrAv3U9CK71BbeZLQ:1630619189766&tbm=isch&source=iu&ictx=1&fir=hyf40v1P6rRpDM%252C8yiKlWGz0XjIdM%252C_&vet=1&usg=K_Nbz7H1lSAlaJEX6q0gauX7u1-Ao%3D&sa=X&sqi=2&ved=2ahUKEwiBjsfsoeHyAhVpQfEDHThdBm4QuqIBegQIbBAD&biw=1920&bih=937#imgrc=hyf40v1P6rRpDM

Maybe there is someone similar near you offering a similar service - might be expensive - we had a full system made & fitted for our SL back in 2003/4 by PD Gough's they even asked me how loud I wanted it to be - they baffled it accordingly so you can't tell it from a standard system it was way cheaper than a genuine MB system.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on September 05, 2021, 03:20:37 PM
Thats an interesting thought. If I can find a reasonably local supplier.

There are plenty of places selling exhaust pipe and pre-bent mandrel bends. Now....my little home MIG kit isn't up to a neat job ( not my welding skills at fault...surely...I mean....blobs and spatters add character..) but I could tack weld bits together and get them professionally welded up. Most custom pipe makers seem to need the vehicle to build the system on, which is a bit of an issue for me.

To ride the bike..I need an exhaust...which means I either paying for a trailer job, or finding another way. It's either that or finding someone who has the right patterns for making up a suitable system. I've contacted a couple of possibles, and will see how I get on.

Could be interesting!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on September 05, 2021, 04:11:08 PM
I've made accurate forms in tube before for rally car roll cage on which the tubalist (made up name for man wot bends pipes) got me to bend sections in aluminium welding wire to work from as they involve compound bend section. He was very competent in that craft though, but it is relatively easy to interpret if given an accurate form.

You can also do things like thread foam pipe forms (like those swimming float things) onto the wire to get clearance etc.

Spattering on fluxed welding wire, keep anything with flux component in airing cupboard or similar ensuring it's bone dry as it's the moisture content that makes it spatter and stick. It's much more consistent when dry and you'll usually be able to use a more accurate amperage to weld with if you're not coping with it being awkward.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: K2-K6 on September 05, 2021, 04:21:36 PM
Also may be of interest
 [attachimg=1]

Loose copy of Yoshimura pipe made by "Carpy" expat brit bike builder in USA,  he has ordinarily been helpful of shipping protocols from what I've read and so may be an option you'd like.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on September 07, 2021, 04:11:59 PM
Well now ..... that is a decent looking pipe!

It's added to my 'watch and ponder' list. The Dekovic pipe is broadly similr....but this seems to keep a flat run under the sump, where the Delkevic has an odd shape to it that spoils the look.

Much appreciated with regard to the suggestions on both welding tips ... and how to get mockups done for piperation by a proper pipist. I am sure they have a real name.....but like you...I have no clue what it is!

I would love to learn proper TIG welding...but the cost of the kit and the consumables is one I can't justify with the use I would get from it. I bought my MIG and taught myself after we bought an old VW Beetle...and I got a shock with the cost of welding simple patches. Plus the quality was not good. When the next bit of work needed doing, it was cheaper to DIY it, as plenty of repair panels with swaged edges were available but while I can get the penetration, and produce welds good enough to pass muster at MOT....it's a lot of work to clean up....and welding pipes, I know the inside will be ugly.

Still...I will just have to make do with re-watching Alan Millyard just 'bashing up' a petrol tank in 1.5mm ally for his replica 6 and tig welding it in his shed, and pretend I will live long enough to learn to do that
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on September 21, 2021, 12:40:36 PM
So....decided to sort out the seat arrangements while I wait for brake parts and some other odds and ends.

I picked up a fibreglass single seat, basically a wide CR one for not a lot of pennies. The seat the bike came with was a non-standard wreck, being a US king and Queen thing, complete with buttons...torn cover and a base so rotten the foam was tougher than the metal. The 'buttons' having been shoved through the foam, and pop rivetted to the base. Great...so water poools in the buttons recess, wicks down the string...and rotted the base out. The only parts of the seat that were worth saving were the hinge...and the catch.

My philosophy remains to use what I have that is 'right' and ruin nothing of what Mr Honda made.

Now, I have used race seats before, and found them a PITA to get on and off when needed, so I wanted to retain the original seat mounting and lock....which required a bit of thought!

The stock hinge was too tall...and if I had use it, the seat would sit about40mm above the frame rails, so out came the thinking cap. The lock was also too long...so I started there:

(https://i.imgur.com/tJsq3ZU.jpg)

An 8mm bolt was found, and a sleeve made to fit over the end. The bolt head was almost removed, and the tip shaped to a dome to mirror the shape of hte stock lock core. A slot was cut, and it was then shortened by the required amount. The RC Car parts bin provided what was a 1/8 scale shock spring which I cut down to fit and provide the right spring rate. This lot went together to make a lock piece that was quite a bit shorter than stock. The threaded part of the bolt was cut down once the thing was all fitted and the exact length known.

The hinge on the other side gave more problems. Putting the seat where I wanted it....the hinge was half under the seat pan, half in fresh air under the hump. No good....so as I needed a much flatter profile hinge..I started from scratch. Found some steel of the right thickness...cleaned it up...and made a hinge plate that was beefier than stock....but basically reversed the way the hinge worked. It also stepped the hinge forward so the mounting to the seat was all on the flat pan part. An ally spacer shim was needed to lift the hinge a fraction, as the seat would foul on the mounting studs otherwise, stopping it sitting level.

(https://i.imgur.com/w5Wqbq3.jpg)

The bottom part of the stock hinge was then used to attach to the seat itself....the stock pin slots through sweetly, with a spring clip to hold it in rather than the dog earted old split pin. The flat surface of the hinge that used to sit against the frame now sits against the seat pan.

(https://i.imgur.com/oFzc6AE.jpg)

Bolting the hinge to the seat required another ally shim, just to get the spacing perfect and to ensure the seat sat flat, and everything sat where it should without stressing the seat. Big washers went on top to spread load. I may glass in the shims later to hold them in place.

(https://i.imgur.com/yj2F54i.jpg)

The lock part was fixed to another ally plate, and that was bolted too the seat pan. The catch needed to sit slightly outside the seat, hence the plate to step it out. This will be covered up with a bit of fibreglass and blended so you can;t see the fixings. It will look a bit neater after this. Stainless bolts and nyloc nuts were used for all fixings.

(https://i.imgur.com/aiVoP0g.jpg)

The seat opens and loses nicely, and the latch engaes securely, opened with the key as before. The front part of the seat sits on 2 3D printed blocks that clamp around the frame and give a flat platform for the seat to sit on. If I need to...I will put a pair of nylon rods into the blocks, with clips to go through. This would stop any wobble at the front, but I haven;t had an issue with this so far...but riding over bumps might rattle it. Some rubber pads sit on top of the blocks ( old inner tube currently! )

So, with the lock mounting covered with a bit of GRP and a pad glued onto the seat base....it will look just how I want. The seat opens to clear the battery compartment and a battery will slide in without issues. It also sits high enough over the frame to clear everything...without looking 'detached'

The next job is to cover up the gap between the seat and the rear of hte tank...and I have an idea for a small 'storage' box that might work.... or I end up with a flat piece of ally and a longer bit of seat foam.... will see how that goes


(https://i.imgur.com/TbTpelb.jpg)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 06, 2021, 09:41:39 AM
This week....I decided to unbreak the broken brakes......

The front calipers weren't bad, but the pistons had the beginnings of rust pitting which I reckon would have made the seals weep. Literally. The rear was a horror. The piston had needed brutal treatment to shift it, and there was corrosion inside. Much polishing and a bit of dressing with fine wet and dry was needed, followed by a bath in the ultrasonic cleaner to make sure they were spotless and free from dust. The wallet was opened with much ceromony ( and moth sprays ) and £100 was spent on stainless pistons, seals, rubber boots, and the like. Half measures were not considered ...and a can of VHT spray ( as recommended on here ) was bought too.

(https://i.imgur.com/vzCLVwZ.jpg)

Brake carriers were stripped and painted. Silver up front and satin black at the rear. The calipers were painted.....and hung on the line to dry. The VHT paint impressed me. It went on well, covered nicely, and just felt 'good' to work with. A mist coat followed by a few more proper coats on rubbed down and degreased calipers, and they looked OK. The missus was out....so in the oven they went as per the instructions. 1 hour at 200c ..... balanced to keep the paint clear of the baking tray was what the recipe said. Boy, did it stink! When I opened the oven after the bake, the fumes fair made my eyes water! But after much airing of the kitchen and a clean of the oven....all was well. Dinner tasted OK......so all good!

The calipers had developed a bit more of a 'shine' than they had before, and were more semi gloss than satin....but I was pleased with the finish and it looked OK to me!

(https://i.imgur.com/Lmi9mRt.jpg)

Everything bolted up well, with the seals given a smear of lube to help the pistons slide home. Fresh seal gaiters all through finished off the job. I am pleased with the end result. More so than I am with the photography anyway!

(https://i.imgur.com/GFCO0hH.jpg)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Spitfire on October 06, 2021, 10:07:03 AM
That looks great and reminds me of doing the same kind of job on my F1, very satisfying.

Cheers

Dennis
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 12, 2021, 06:22:04 PM
Been a busy beaver in the shed again today.

We have a solution for the brake master cylinder problem.....and a nice way to get some footrests that will work with the seat and bars. So....what did we do?



Having decided that a pair of rearset footrests was going to fit with the way the project is evolving and with the riding position my seat and bars required...I looked at prices to see what it was going to cost me. I looked at hte cheap chinese ones the filled most of my search, and discounted them. I have seen how good they aren't when a friend bought a set. What a bargain...until you looked at the build quality, the poorly cut therads that vibrated loose, and the generally poor and sloppy linkages. No...that was out. I then looked at hte prices of the well known branded items. Ouch. So on went the thinking cap.

So, why not find a bike with the right sort of setup, and adapt that to fit. Simple!

So, the search was on. Didn't take me long to find a suitable donor pair. Off a CBR600F3....so it's at least Honda. For £60 I managed to get a somplete left hand footrest assembly with gearchange linkages, complete, AND a complete right hand set with brake lever, master cylinder, even the brake light and wiring and brake pipe.

Mocked up a couple of flat wooden brackets to sit over the swingarm pivot bolt and lower engine mount, where the F2 stock footrest carriers go. That allowed me to get the position right, and made sure I had clearance for the MC and brake light switch etc. It all fitted REALLY well. I even found the splines on the gearchange linkage are the same size as the ones on my F2. Might need to change the length of the linkage rod...but thats just threaded M6 x1.0 both ends, so no problem to make that if I have to.

Now I need to order up some 12mm thick ally plate to carve my actual mounts out of, 12mm so I can use offcuts to make the additional spacers to recreate the 25mm thick stock pieces. As it's all stock proper parts, the controls look neat, and it all fits and works perfectly.

(https://i.imgur.com/4JcrApz.jpg) (https://i.imgur.com/563m9Or.jpg)

Will need to swap the pipe around, as the curved front banjo is angled which doesn;t work, but the fixings are the same size. So thats all good.
The only potential fly in the ointment is the master cylinder not being right for the brake. My estimated measures say it's about the right bore size....so should work. Time will tell. But as my stock MC was not in good shape, and even with a rebuild kit needed a new linkage and pushrod....which I still haven't been able to find...even if I got a seal with the stocker, I was struggling for parts

edit: looking at it now, I might need to bring the lower mount point forward, to more closely reflect the angle Mr Honda put it at. But I will fine tune that in the mockup before I cut metal
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: andy120t on October 13, 2021, 06:55:58 AM
Just looking at your earlier posts about exhausts -Predator motorsports in Welwyn make stainless exhausts for bikes. Might be worth a call there. They've been around for ages but I haven't personally used them.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on October 13, 2021, 10:02:55 AM
thanks for the tip Andy... Predator are on my radar, but the more I think about it, the more I have to conclude I will either have to compromise....or get a more bespoke solution. That will depend on how the finances look when the time comes. I've been out of work for a few months, and am watching the pennies closely. I have a chunk of money from the sale of my old Hornet in the bank for the bike fund....so we will see. The more I can save elsewhere, the more will be there for shinies :)

But I do have a plan B ..... or is it C .... or D ... if I can just get the damn stock headers apart!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on November 20, 2021, 01:50:37 PM
Following the shjocking revelations in Practical Sportsbike that my great idea was absolutely not original, already done...and therefore old-hat, I was not discouraged.

My first attempt was a tragedy of epic proportions, but was enough to convince me the idea was a good one, but my approach was wrong. I tried to build a mould out of the rear section of the tank, and then remove material to narrow it down ..... as it would otherwise be too large. Sadly.....what also became apparant, was that every other curve, slope and angle also appeared wrong. By the time I had chopped it a couple of times, taped the bits back together and offered it up a load of times....I could see the thing was never going to be blending in like I wanted.

So I binned it.

Not to be beaten, however, I had another go. I had bought some expanding foam filler for a job on the house, and had about half a can left...so I made a little polystyrene base, greased up the back of the fuel tank, covered anything likely to get gunk on it ....and sprayed up a big pile of foam to fill the gap between the back of the tank and the seat. Took a copuple of goes to get it all ....as put too much on and its prone to sag...but it was done!

Then I could carve it back once fully set and blend it with the tanks curves, forming the shape I wanted. It sands really easily, and can be chopped to a rough shape with a saw. Card templated helped me to get it symetrical.

I made it undersize.....as my plan was to lay the fibreglass straight on it, tidying up the surface with a thin skim of filler.

The final cutting of hte edges and the surface finish has yet to be done, but I like whats done so far.

(https://i.imgur.com/K6vhcrM.jpg)

(https://i.imgur.com/Tai9rQl.jpg)

The fit at the back isn't perfect, and needs some fettling...which is making it ride up slightly and angle to one side when let go of. Push it into place, and it looks spot on though.
Once I finish trimming the back and getting it square, it will fit. No idea why the first pic has come out blurry....but you get the idea. Next job is to sand it flat, and apply filler to the imperfections.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Laverdaroo on November 20, 2021, 02:51:42 PM
 ;)
Now that's coming on a treat, good skills!
I read about your rear-sets and thought straight away, before I'd got to the end of the sentence......."CBR600 of some incarnation will fit". They read that's what you did! Im not that soft then? Winning! ;D

Re the master cylinder, I shared this with Allen on his disc conversion but have you had a look at the HRC M/C option?

Much cheapness, bit racey :o, still Honda but most of all............its only £14 and HRC!!!!    Whoop whoop!


Ebay item...162805847400
I had one on my Ducati 748/853 and was so simple, worked a treat and very unobtrusive but looked great. (if you're an HRC lover as I am) 8)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: haynes66 on November 20, 2021, 04:40:59 PM
ive had a look on ebay and it doesnt show much. what do you get?

pete
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on November 20, 2021, 04:54:04 PM
If I have this right....the 'reservoir' ... is not a pot, its the long greenish coloured tube. There is a bung in the top to keep the fluid in and the water out if it rains. Then there is a clip to fasten it at the MC end, and a jubilee clip for the other end? Think thats right.

It's cheap because it's pretty simple...but in my case, I reckon it would tuck up quite neatly behind the side panel which is tight on space due to the oil tank being in there. I will snag one becuase I think it's a neat solution and fits with what I am doing. The tube only needs to hold enough fluid to account for one 'piston' full in the MC to work the brakes, so I guess race teams looked for how to store just enough and no more.

@Laverdaroo ...thanks for the tip, and the nice words :)  I wanted to stick with a Honda solution, and get something affordable. But I definitely wanted rearsets. Cheap imported ones are out there, but I have seen the quality, and often its awful. You want solid dependable pivots and I figured this was a way to get pegs and controls that looked neat, worked well, and were well finished. That and the fact that CBR600 bits were silly cheap, getting a full set of pegs, linkages and M/C for peanuts. Even allowing for the big chunk af alloy I bought..... it's still cheaper than a set of Chinesium rearsets. Winning for sure!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: haynes66 on November 20, 2021, 05:25:36 PM
splendid, thanks.  nice work by the way.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Laverdaroo on November 20, 2021, 10:11:15 PM
It's a small kit but like you say, it tucks away, looks neat and does exactly what you suggested you needed. Its compatible and to those that know, is cool as hell!
It may be a clip, a tube and a stopper for 14 quid :'(, but..................... its and HRC clip, tube and stopper :o 8) ;D

Pleasure and lovely bike coming on there, the cbr rearsets are cheap as there's billions out there and heaps were raced making standard parts easy to get hold of and the spares market is still really cheap for bits and bobs. You're right to not do the chinese thing, you have to stand and put your weight on those crap things; I wouldn't be trusting any of those at all and I reckon you've done it justice by grabbing those bits.
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on November 24, 2021, 06:34:13 PM
hehe heh.... I am now the proud owner of a genuine HRC branded jubilee clip, a similarly branded piece of plastic tube, a bung and another clip.

should tuck in nicely :)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: Laverdaroo on November 24, 2021, 06:37:38 PM
Whoop, whoop!

You are now a proper cool dude! 8)

whats not to like about anything HRC? ;D ;D
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on January 03, 2022, 05:40:37 PM
The unseasonably warm weather has allowed me to get some primer on the tank, and to finish off my extension piece.

I have made a 'hook' mount where the little tool tray bolts on .... and made a similar loop glassed in under the extension piece. An elastic loop ( Ok....its a strip of inner tube.... ) is looped on and clamps the piece down and forward. There will be another mount at the back....but that elastic hook is to hold the front edge down, and do so in a way that shouldn't risk damage to the tank.

The tank has got a coat of primer too.

Next job is to make up a rear number plate mount, which will go between the rear frame rails. Indicators will also be added at the back, bolted through the mounting holes at the end of the frame rails. I also need to work out a method of baking paint on engine cases.....they don't fit in the oven. Maybe I get myself a gas barbeque for the summer......

(https://i.imgur.com/FFzJ60T.jpg)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: philward on January 04, 2022, 06:03:46 PM
 I also need to work out a method of baking paint on engine cases.....they don't fit in the oven. Maybe I get myself a gas barbeque for the summer......

I used a similar method to this youtube video only I used 1/4 ply - it worked well. Other members used similar I think. Will be re-assembling mine to paint the cases on an engine I will be building this year (from spares I have accumulated over the years).

https://www.youtube.com/watch?v=21AsnM71YM0
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on January 04, 2022, 06:23:13 PM
excellent!

Boxes I got plenty of ( left over from moving house in the summer) foil I got..and a heat gun.

I am a little surprised a cardboard box can take the necessary heat...but...well..YouTube guy didn;t set fire to it...so I am convinced :)
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: philward on January 04, 2022, 06:57:48 PM
I used 1/4 ply that I gaffer taped together (which was soggy after the oven was used) - although with more patience, I could have screwed it together. I tin foiled a plywood base so I could place the box on or off crankcase easily. Make sure you make the bax tall enough for the crankcase and something to stand it on (I used a cut off a left over railway sleeper) so that the hot air can circulate around the crankcase.
I had a spare sheet of 1/4 ply but 3/8 ply would be easier to screw together. Once its all cut, you can assemble and de-assenble for ease of storage (as for most of us, its infrequently used).

There is a picture on a thread somewhere but for the life of me, I can't find it!
Title: Re: CB750F2 .... silk purse from a sows ear.
Post by: SumpMagnet on July 02, 2022, 12:40:02 PM
Not been able to do much recently as I was dealing with a few health issues that were affecting my ability to do any work out in the garage, but I need to get things moving again.

To spur me on, I did what any sensible guy would do, and spent some money.

Bought a set of Zed Parts stainless engine mounting bolts. Very nice they look too. They also will supply a shorter mounting bolt for the 12mm one that goes through the footrests for those fitting rearsets. As I am one of those folk....a shorter bot avoids having 30mm sticking out the end. Supplied with fresh nuts all round, they do look rather nice.

(https://i.imgur.com/ljPGrFW.jpg)

Now I got to go make those footrest hangar plates.

Also managed to modify a cheap steel rear mudguard off E-Bay to weld on some mountings to fit the frame rails, plus fitted a rear light, indicators and number plate mount. Matching small front indicators are also fitted. Wanted indicators for practicality, but didn;t want ones that stuck out like a sore thumb.

(https://i.imgur.com/ZywveSZ.jpg)
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