Honda-SOHC

SOHC.co.uk Forums => Project Board => Topic started by: Skunky on August 20, 2018, 08:50:35 PM

Title: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on August 20, 2018, 08:50:35 PM
Hi

I have decided to detail my restoration of a 74 CB400F here.

The bike was imported in may and shows 6700 miles and is in a pretty sorry state. The ignition switch is missing and it looks as if it stood for a long time.
I took the tank and seat off and it looks ok. The front wheel is out of line but the frame seems ok. I expect that The triple trees need adjustment. The front brake is buggered and the brake fluid has turned to crack cocaine. Which can only make it faster 👍
Apart from a broken headlight and missing switch/keys, everything is there. The engine turns over on the Kickstarter and there’s new oil in it. I suspect someone has tried to start it.

Here are a few before photos

[attachimg=1][attachimg=2][attachimg=3][attachimg=4][attachimg=5]
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on August 20, 2018, 09:09:30 PM
Like every builder I started looking online to see the cost of the Honda parts and while on eBay I saw a headlight which I negociated down to £32. It arrived today I was surprised to see it was original old stock. Result 👍
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: JamesH on August 20, 2018, 09:28:29 PM
Great project you have there. Will follow with interest..
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: petermigreen on August 20, 2018, 09:34:47 PM
Good luck on your adventure.
I'm not sure how you'd adjust the yokes. I would expect that you might find the fork stanchions are bent. Be interesting to see how that turns out. If they are you can have them straightened or replaced at your preference.
Sounds like you've been lucky with missing parts. All the parts you've got just need sprucing up  ;D
I'll also be following with interest.
Peter
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: paul G on August 20, 2018, 10:17:23 PM
Great starting point. Give philpots a ring on the stantchions.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Nurse Julie on August 21, 2018, 08:41:36 AM
Is that a crack on the lower fork case.....or a USA cobweb ?

[attachimg=1]
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Sprocket on August 21, 2018, 09:04:46 AM
Looks like a solid base to start from! Those engine bars though!  :o
Where are you starting with the project then?
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: SumpMagnet on August 21, 2018, 09:26:40 AM
Looks all there...and not too far gone. These are pretty little things when sorted...and every time I pick up heavy great lump of 750 I kind of wish I had started something smaller!

I've not been here long, but already I have learnt a lot and had a load of help.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on August 21, 2018, 10:05:25 AM
First thing is to make sure I can straighten the front end up and That the frame is true. Compression test the engine and maybe start it. Then once I’m sure it’s not a complete lemon I will start the strip down. I will take it back to the frame. Clean and repaint frame and then re build using as many of the original parts as possible. I don’t expect it to be a quick build and as I have never refurbished a bike before I will have to make sure it is as good as can be. It can’t be 100% as there is age related damage which can’t be polished out such as a broken fin on the cylinder head where something was dropped on it. I also intend to upgrade the electrics to a more modern standard with improved lights and indicators and possibly an m unit and rewire new tank, paint and decals and a lot of cleaning polishing and new chrome where required.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Laverda Dave on August 21, 2018, 11:30:03 AM
Good luck for the rebuild.  Plenty of help on here.  Good news about the Cibie, I bought a similar NOS one a couple of years ago, its still in the box to this day!
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on August 21, 2018, 02:07:53 PM
Those engine bars though!  :o

If you like them you can have them  :o  I'll even throw in the cheap u bolt used to attach it to the frame.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on August 21, 2018, 02:13:16 PM
Good luck for the rebuild.  Plenty of help on here.  Good news about the Cibie, I bought a similar NOS one a couple of years ago, its still in the box to this day!

Not a Cibie, I suspect it's the original headlight from a bike which had a Cibie conversion, the shop then dropped the old headlight into the Cibie box and relabelled it so they knew what was in there. You can clearly see the Stanley logo on the front of the glass.

Still a good find though.

Oddjob

They had put a label showing it as a Stanley on the box and that's what I was referring to as original.  I didn't even notice it was a Cibie box  ::)
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: SumpMagnet on August 21, 2018, 03:59:26 PM
You have to keep that classy speedo :) Love the crackle effect transfer!
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on August 21, 2018, 04:18:53 PM
You have to keep that classy speedo :) Love the crackle effect transfer!

It will go the same way as the crash bars  ;D ;
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: kent400 on August 21, 2018, 05:07:17 PM
The speedo isn't the original, looks like a CB350 Four one. The original would have been marked to 120 mph but one marked to 130 mph was often fitted on those supplied to the USA market. Gauges with crazed faces are often found on bikes imported from the USA, they have sat in the sun too long.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Rob62 on August 21, 2018, 08:38:08 PM
Great project! Will be good if you can keep it as original as possible i.e. clean and refurb rather than replace..... good luck
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on August 22, 2018, 04:27:11 PM
Is that a crack on the lower fork case.....or a USA cobweb ?

(Attachment Link)

Trust a Nurse to spot a fracture 😂

If you look at this one you can see the crack has slipped down to the mudguard. Scared me for a second though.

[attachimg=1]
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on September 03, 2018, 10:45:12 PM
Hi All

Started on the project today. First thing was to straighten out the front end to make sure the frame was ok. I loosened the fork pinch bolts and realigned the handlebars and front wheel and it all looks much better. I then put a little oil in each cylinder before completing a compression test and was pleased with the results.

[attach=1][attach=2][attach=3][attach=4]
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on September 03, 2018, 11:04:17 PM
Next I fitted a new ignition switch and put some power on. I turned the bike over on the starter button and it turned over great. The spark was very weak, if there at all. So checked the point gaps and cleaned the points and now got a spark. Thought I would see if she would start but I’m getting fuel leaking from one of the carb overflow pipes. That’s a problem for another day.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on September 04, 2018, 05:00:32 PM
The speedo isn't the original, looks like a CB350 Four one. The original would have been marked to 120 mph but one marked to 130 mph was often fitted on those supplied to the USA market. Gauges with crazed faces are often found on bikes imported from the USA, they have sat in the sun too long.

I think you are right Kent. It looks like a 350 speedo to me too. Which means I will need to find a 400 one.  :-[. I didn't believe the mileage looked right and it was odd that the speedo was crazed and the tacho clean. Shit happens though. I do know it has no oil leaks and good compression on all pots. What part of Kent?. I grew up in Swanley.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on September 09, 2018, 04:36:44 PM
Why won’t my bike start?. Dear oh dear 😂😂.

Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Nurse Julie on September 09, 2018, 04:53:53 PM
Oh dear oh dear indeed 😁😁😁😁
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: SumpMagnet on September 09, 2018, 05:30:21 PM
Oh ...my....gawd...what the hell IS that in the carbs! I can't believe that was ever petrol.

I think those might need a bit of a clean........
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on September 09, 2018, 07:10:11 PM
Oh ...my....gawd...what the hell IS that in the carbs! I can't believe that was ever petrol.

I think those might need a bit of a clean........

I’m not sure what happens if you leave fuel in for a very, very, very long time. But I can’t believe it would be sticky. I think there may have been some sort of separation and then new fuel put on top. It’s actually worse than it looks, all of the floats are stuck or rusted in place and there’s a sticky varnish everywhere. I’ve ordered a carb service kit with new jets and gaskets but I suspect I may need to throw the floats too and fit new pins. I may soak it in cider for a few days. Normally makes me feel better 😀. Actually the top ends look remarkably clean.
Any suggestions ?
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Nurse Julie on September 09, 2018, 07:16:11 PM
Soak in thinners if you are going to get new floats.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Spitfire on September 09, 2018, 07:29:26 PM
Not as bad as those but I had the same sort of thing on my 750F1, I left it in the garage for 10 years when I was working overseas and when I got back I couldn't open the throttle, couldn't figure out why until I took them apart, they were all glued up inside.
Here's one of the float bowls, and no I did not have to use the hammer !
(https://imageshack.com/a/img924/945/zErq7T.jpg)

Cheers

Dennis
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on September 18, 2018, 07:44:25 PM
The Carburettor kits arrived today  :D. I filled the float chambers with thinners and put the carbs back on top, they have been soaking for 5 days. I have managed to get two of the floats out.

I have invested in a Ultrasonic cleaner and starting tomorrow will begin the strip down and clean up. I will take photos and hopefully I will have them good as new.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: K2-K6 on September 18, 2018, 08:12:46 PM
In running a chemical analytical laboratory we'd generally use steam to clean various tarring etc from the lab glass. 

You can use one of those domestic steamers that produce a jet of steam to get an initial clean and possibly free the floats prior to more detailed ultrasonic attention.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: mike the bike on September 18, 2018, 08:33:37 PM
Or a steam wallpaper stripper.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Nurse Julie on September 18, 2018, 09:25:18 PM
Or a veggie steamer saucepan thingy, just chuck everything in the basket, put lid on and let it steam away. I picked up a double layered one in the charity shop for £8.00....worth every penny and more.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Rozabikes Tim on September 18, 2018, 10:21:44 PM
What does the wife say about that on the stove Julie?  ;)
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Nurse Julie on September 18, 2018, 10:54:47 PM
What does the wife say about that on the stove Julie?  ;)
Who, Trig, absolutely nothing, he knows better than to object to anything i do in my kitchen 😀😀😀😀😀😀
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on September 19, 2018, 01:40:39 AM
My Partner has a hand steamer thingy in the garage that she never used.

What a waste of money! The sh#t people buy!.  I said.

I will try it tomorrow. FFS DON@T TELL HER  ;D
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on September 22, 2018, 05:21:34 PM
[attachimg=1][attachimg=2]So begins the carb cleansing

Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on September 25, 2018, 12:53:50 AM
The postman came today. Don’t you love it when he brings something shiny. If I outbid you for this beauty then I don’t apologise at all 😂😂[attachimg=1][attachimg=2][attachimg=3]
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Nurse Julie on September 25, 2018, 08:20:34 AM
😎😎😎 is that real chrome, they look very, very, very shiney.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: SumpMagnet on September 25, 2018, 04:29:46 PM
Put your shades on before looking too closely...that is very shiny. Now you won;t be able to ride in the damp/wet/vaguely possibl;e chance of moisture for fear of dulling the finish :)
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Northy on September 25, 2018, 07:08:03 PM
You out bid me !  are they DS or genuine ones , the guy didnt know.

I do have one shinny set but need another set by the spring and then I got another 400 f which will be a special (Delkevic) and I'll soon do report on here.  Yes I've got 3 of 400/f  and a GPZ400  !!!
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: adriangsmith on September 25, 2018, 07:40:59 PM
Outbid me too. And got. Outbid on the other set I bid on as well. Need a set so I can get rid of this grotty Motad system!

Sent from my CLT-L09 using Tapatalk

Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Nurse Julie on September 25, 2018, 07:45:17 PM
The collector box wasn't chromed on the OEM ones, mine isn't and there is usually a grey weld line(looks like chicken shit weld) around where the two fixed pipes fit into the collector. I take it this set has been rechromed hense the extremely blingy OTT finish ?
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on October 06, 2018, 08:06:58 AM
[attachimg=1]

Parcel arrived replacement tank, speedo and switchgear thanks to Vortex  ;D
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on October 06, 2018, 11:59:31 AM
Hands up if you have been caught out by the spring and ball bearing on carburettor 4 choke lever assembly  [attachimg=1]
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Laverda Dave on October 06, 2018, 12:20:39 PM
👍. Are you on your hands and knees looking for it somewhere on the floor?
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on October 06, 2018, 12:50:48 PM
👍. Are you on your hands and knees looking for it somewhere on the floor?
No Found the ball bearing on the workbench. Never found the spring. Managed to re-purpose one from some bmw bits I had left over.  8)
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Nurse Julie on October 06, 2018, 01:04:23 PM
Im putting half a hand up as I never new the spring and ball were there until we had an in depth discussion on here about what made the 'click'  when moving the lever up and down. I was ready for the little blighters when I took mine apart.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on October 06, 2018, 01:39:55 PM
Still, The carburettor rebuild is nearly complete. All the carbs have been scrapped scrubbed and cleaned in an ultrasonic cleaner, tops and bowls polished, new jets needles and seals fitted and reassembled. Then Disassembled as the light dawned on the missing spring. A manual set up bench set up to get it as close as possible to factory and then should be able to get a start. One tip I could pass on. I managed to rescue the floats but the pins were of course ruined. I bought a 2mm model makers brass rod from fleabay for £2.99 for 200mm and cut my own pins rather than pay £2.50 each for them. Still got enough for another rebuild  ;D. Got my eyes open for a set of Vacuum gauges but in no hurry.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on November 15, 2018, 06:43:39 PM
Hi Honda lovers, It’s been a long time since my last confession. I finished the carburettor rebuild some time ago and it’s been sitting in the garage calling to me.
Before I start the strip down, I wanted to gauge the engine condition. As previously mentioned the engine turns over and has compression. I put the carbs back on hooked it up to the car battery and tried to start. She popped and spluttered and then

https://youtu.be/CKfXo_9H4Lo

The Engine doesn’t sound too bad for a 44 year old.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Rozabikes Tim on November 15, 2018, 10:34:39 PM
Nice one. Great feeling when they first fire up!
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on March 30, 2019, 09:28:01 PM
Hi Honda lovers

Spring is in the air and I have returned to my CB400 project, which to be honest has been languishing in the garage since October. I had some work to do on my Triumph and still have some to do on my beemer.

Anyway, last year I got the Honda running and was happy with it. The Engine has good compression and ran well.
Today I stripped the Honda down to the frame . Everything came apart well engine out, forks, wheels even the loom.

I turned the frame over to remove the stand and that’s when I discovered a massive problem. When I bought the bike I noticed some iffy looking welding on the side stand. I assumed that it may have had a problem and been botched. Seems I wasn’t wrong😢.
[attachimg=1][attachimg=2][attachimg=3]


Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Nurse Julie on March 30, 2019, 09:33:32 PM
😱😱😱😱😱
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: K2-K6 on March 30, 2019, 09:41:14 PM
Whoa, it's not often you see such a classic example of pigeon-shit welding  :)

Or perhaps even worse and verging on hemorrhoids.

That's not good is it.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on March 30, 2019, 09:41:46 PM
😱😱😱😱😱

I know. Should have heard the language 🤬🤬. I have a welder/ fabricator who has done work for me before. I shall take it to him to see if it can be salvaged. If not I either look for a frame or scrap and sell the parts.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Moorey on March 30, 2019, 09:45:29 PM
It looks like all the original bits are there. A grinder and a competent welder will sort that easily enough.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on March 30, 2019, 10:07:58 PM
In going to go over the frame tomorrow cleaning and de-rusting just to make sure there's no rot. I think a P.O. Must of hot the side stand really hard. Luckily the frame seems true so it should be OK
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Andych on March 30, 2019, 10:39:28 PM
Wow... that makes my side stand area look good... relatively speaking...
Actually... looking at my pic again.. I think they are almost on par..

[attachimg=1]
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on April 05, 2019, 01:20:08 PM
Today I’m a much happier Skunk 😁
Picked up my frame from my welder in Derby and he has done a great job[attachimg=1][attachimg=2][attachimg=3]
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Laverda Dave on April 05, 2019, 03:25:54 PM
Very nice job. You are back on the road to recovery. Keep the progress photos coming.
If the welder is willing to take on this type of work it might be a good idea to post his details on the parts and services section?
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: SumpMagnet on April 05, 2019, 06:47:51 PM
Considering what your welder had to start with...he has done a good job of recovering that!
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Lobo on April 06, 2019, 12:33:17 PM
...the bigger the blob, the better the job.
Surely... 😂
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: K2-K6 on April 06, 2019, 12:46:48 PM
What an improvement,  must be pleased you've got that sorted.

For anyone welding with arc and stick kit,  if you keep the rods in a warm dry place (airing cupboard)  they will weld much better.  The external flux is hygroscopic (absorbs water) and doesn't work well at all with it damp.  Usually it spatters all over the place and gives those blobs seen in the first photos.

If the flux doesn't flow properly over the hot weld it will oxidise during the weld phase and not give the integrity needed either.
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on April 06, 2019, 01:13:41 PM
What an improvement,  must be pleased you've got that sorted.

For anyone welding with arc and stick kit,  if you keep the rods in a warm dry place (airing cupboard)  they will weld much better.  The external flux is hygroscopic (absorbs water) and doesn't work well at all with it damp.  Usually it spatters all over the place and gives those blobs seen in the first photos.

If the flux doesn't flow properly over the hot weld it will oxidise during the weld phase and not give the integrity needed either.

To be honest I think the poor welding was done with the engine in the frame by a complete idiot. He just wanted it back on.

It is apparent that when the bike broke down he just left it standing. Its got no miles on it and the original tyres although I think it's short life was a hard one.

I'm over the moon. I thought I might have to scrap it but now I can start the restoration. I intend to leave the bike standard and clean up as much as possible without removing the patina of age. 
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on April 20, 2019, 07:15:52 AM
Frame cleaned back to metal and painted [attachimg=1][attachimg=2][attachimg=3][attachimg=4]
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Laverda Dave on April 20, 2019, 03:40:53 PM
That's a very smooth finish, hand painted?
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Woodside on April 20, 2019, 03:52:35 PM
And what paint did you use?
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on April 26, 2019, 12:40:04 PM
That's a very smooth finish, hand painted?
No, rattle can 
Title: Re: Yankee Doodle not so dandy CB400 rebuild
Post by: Skunky on April 26, 2019, 12:47:42 PM
And what paint did you use?


Its just plain old Halfords Gloss black.

Wire brush back to the metal, Knock off any lumps, Sand until smooth,
 Two coats of undercoat. four topcoat and two lacquer.
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