Honda-SOHC

SOHC.co.uk Forums => Project Board => Topic started by: kiki.o on December 08, 2021, 12:24:12 PM

Title: 1975 CB 400 Four - Restoration
Post by: kiki.o on December 08, 2021, 12:24:12 PM
Hi to all,

I am in the middle of the restoration process, so I have decided to join the forum in the search of some answers.

Here's the process so far... I bought the bike in 2016 as a cafe racer build, but somewhere down the stripdown process I decided to restore it. Not that have gave up on the cafe racer idea. :)

Here are a few pictures, hope you like them:

The day I bought it:

(https://i.imgur.com/w0GFFbh.jpg)

The assembly begins:

(https://i.imgur.com/mB4h9E7.jpg)

The painting process:
(https://i.imgur.com/Aw43P7q.jpg)

(https://i.imgur.com/E8lQPAv.jpg)

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

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

(https://i.imgur.com/imi8CzY.jpg)

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

(https://i.imgur.com/WsvPjs0.jpg)

(https://i.imgur.com/vFu6O0q.jpg)

First of several gloss finish

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

(https://i.imgur.com/SpD8xLN.jpg)

Final polish:

(https://i.imgur.com/v4QTrOz.jpg)

New rear shocks:

(https://i.imgur.com/RdvUk9M.jpg)

Front shocks restored with all available new parts:

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

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

(https://i.imgur.com/elUNF6x.jpg)

(https://i.imgur.com/KeJXvw6.jpg)

New labels :

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

(https://i.imgur.com/Wpo3kv4.jpg)

Some parts refurbished

(https://i.imgur.com/9DxEeBg.jpg?2)

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

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

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

Footpegs restored:

(https://i.imgur.com/aQxIxTA.jpg?1)

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

(https://i.imgur.com/HlW8L6T.jpg)

(https://i.imgur.com/bzNm0vd.jpg)

Expanded the carriers for new coils (DynaCoil 5ohm)

(https://i.imgur.com/xn0vXjG.jpg)

Refurbished the airbox bleeder housing(don't know the exact name, sorry :))

(https://i.imgur.com/T1O2lQg.jpg)

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

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

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

Wheels laced

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

(https://i.imgur.com/IOmC6XZ.jpg)

(https://i.imgur.com/e8MNRrV.jpg)

(https://i.imgur.com/6XDL9wq.jpg)

(https://i.imgur.com/P2GK7Z2.jpg)

Wheels finished:

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

On wheels now:

(https://i.imgur.com/6sORQFF.jpg)

Instruments and headlight rebuild:

(https://i.imgur.com/GZ6wFW6.jpg)

(https://i.imgur.com/dezLsP9.jpg)

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

(https://i.imgur.com/m05eZEz.jpg)

(https://i.imgur.com/g3NPc3V.jpg)

(https://i.imgur.com/GU2PIpE.jpg)

(https://i.imgur.com/H9gUiCv.jpg)

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

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

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

(https://i.imgur.com/x4E17vi.jpg)

(https://i.imgur.com/Shm8Owp.jpg)

(https://i.imgur.com/x6w1ZXF.jpg)

Headlight rebuild:

(https://i.imgur.com/V2lDFys.jpg)

(https://i.imgur.com/Dfj3GRX.jpg)

(https://i.imgur.com/Ox0EJuY.jpg)

(https://i.imgur.com/Q5q5SIl.jpg)

New front brake

(https://i.imgur.com/0O4lKVe.jpg)

New rear brake

(https://i.imgur.com/LiMl7W3.jpg)

New blinkers:

(https://i.imgur.com/yFoq0iJ.jpg)

New controls:

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

Engine rebuilt. Not done by me obviously, not on that level of expertise for now :)

(https://i.imgur.com/oqdo9zD.jpg)

painted cylinder studs

(https://i.imgur.com/UvtLla3.jpg)

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

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

(https://i.imgur.com/tOqhAw2.jpg)

(https://i.imgur.com/aLZ6zQi.jpg)

(https://i.imgur.com/3kXVWAM.jpg)

(https://i.imgur.com/3JArJYI.jpg)

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

(https://i.imgur.com/LmyT24r.jpg)

(https://i.imgur.com/rqSt3AC.jpg)

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

(https://i.imgur.com/QDVm4OU.jpg)

And that's about it for now...

This is what it looks like for now:

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

Now onto the electric mess, trying to wire up everything and I do have a couple of questions but, at the moment, the wiring diagram answers the majority of them   ;D

Sorry for the long post  :)

Best regards,
Kristijan





Title: Re: 1975 CB 400 Four - Restoration
Post by: Deano400 on December 08, 2021, 12:42:55 PM
Hi kiki.o
Welcome and a lot of good work done there.
In the picture of the breather chamber you have the drain pipe connected to the inlet. The drain should be on the bottom stub and the rocker breather pipe on the side stub.
Title: Re: 1975 CB 400 Four - Restoration
Post by: Johnwebley on December 08, 2021, 12:44:56 PM
Great build,,

Well done, and welcome

Sent from my SM-A750FN using Tapatalk

Title: Re: 1975 CB 400 Four - Restoration
Post by: taysidedragon on December 08, 2021, 01:15:29 PM
Great work so far. Not much more to do. 👍
Title: Re: 1975 CB 400 Four - Restoration
Post by: heli_madken on December 08, 2021, 02:43:03 PM
Welcome to the forum, great build showing a lot of skill. Paintwork is top notch and I can see you are absolutely meticulous about everything else will make a stunning bike when finished.
Title: Re: 1975 CB 400 Four - Restoration
Post by: smoothoperator on December 08, 2021, 05:15:21 PM
Excellent work there buddy, you sure are tidy. Well documented, great work on the paint, wondered where you were going with the tank lettering then it all came together. Interesting looking coating on the engine and forks.
Title: Re: 1975 CB 400 Four - Restoration
Post by: philward on December 08, 2021, 06:09:32 PM
Great build and well documented build history - well done
Title: Re: 1975 CB 400 Four - Restoration
Post by: kiki.o on December 08, 2021, 11:33:45 PM
Thank you all, I am glad you like it.

There is no coat on the engine, it's just raw material, soda blasted. The forks though are RAL9006(if I remember correctly), but I am not satisfied with the color itself. I went for oem looks, but now I am not so sure... Ah well, i need to leave something for the next winter :D

Drain pipe and breather pipe are not yet connected and that will be done once the carbs are in place. Thank you for the heads up.

I started with the electrics tonight:

(https://i.imgur.com/PjRng7K.jpg)

It seems that I have evertything sorted out in the headlight area, but still, I have couple of wtfs and I am not sure what to do next.

The headlight have two wires that seem not to be in use. Orange/white and Light blue/white. Am I right? Seems that the wiring diagram confirms that:

(https://i.imgur.com/IL6hlJT.jpg)

On the connectors by the steering stem, it seems that one wire is missing -  the Light blue one. (RH blinker one)

(https://i.imgur.com/Wh2XFUr.jpg)

Here it is connected, and the cable from the switch does not have it's pair. Am I missing something here? Is there a workaround? FWIW, the main installation is new one from 4into1 and the switch is new one from Honda.

(https://i.imgur.com/BqSaG8X.jpg)

Additional question: Where does this one go? This is near the airbox.

(https://i.imgur.com/BPm2k4e.jpg)

Thanks for any input, any advice would be much appriciated.

Best regards, Kristijan



Title: Re: 1975 CB 400 Four - Restoration
Post by: taysidedragon on December 09, 2021, 10:25:38 AM
I can't remember the colours right now, but there are 2 spare wires up front that are used for daytime running lights in USA.
I suspect the blue ring connector is for regulator or rectifier?
Title: Re: 1975 CB 400 Four - Restoration
Post by: Bryanj on December 09, 2021, 02:40:26 PM
And dont forget to remove the paint/powdercoat where it bolts on, same at main earth wire
Title: Re: 1975 CB 400 Four - Restoration
Post by: smoothoperator on December 09, 2021, 04:50:19 PM
On mine the green earths to the top front bolt on the battery box.
Title: Re: 1975 CB 400 Four - Restoration
Post by: Deano400 on December 09, 2021, 05:06:39 PM
As stated by smoothoperator mine is on the battery box.
[attachimg=1]
Title: Re: 1975 CB 400 Four - Restoration
Post by: Deano400 on December 09, 2021, 05:07:42 PM
That pic is before restoration BTW.
Title: Re: 1975 CB 400 Four - Restoration
Post by: kiki.o on December 09, 2021, 05:39:28 PM
Hi all,

Thanks for the input. Yeah it's the green one, the color is a little bit off, since it's photographed in dark garage by cellphone.

Deano's picture says it all. I'll strip some paint on the connection point and attach it there. Thank you very much.

Any idea on the main harness missing the light blue wire with the female connector? Before I start to torn the main harness down :D

Best regards,
Kristijan
Title: Re: 1975 CB 400 Four - Restoration
Post by: kiki.o on December 12, 2021, 08:00:25 PM
I guess i found a walkaround for missing light blue connector: I'll use the unused line from the bunch to the headlight(light blue/white one), and will make a jumper connection to the blue installation in the headlight. Tried it and it seems that it works for now.

I've ordered new bullet connectors so I can make a new cables , so 'ill have to wait for that one to arrive.

In the meantime, I've put the headers on:

(https://i.imgur.com/54wLQFq.jpg)

(https://i.imgur.com/pX3YjSg.jpg)

(https://i.imgur.com/DPQUGS5.jpg)

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

And recreated new main leads, the old owner was too lazy to replace the connector once it broke off

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

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

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

That's it for now, I have to put the carbs together and maybe give it a go?  8)

Best regards,
Kristijan

Title: Re: 1975 CB 400 Four - Restoration
Post by: Johnwebley on December 12, 2021, 08:08:12 PM
Very nice tidy work, it's looking good

Sent from my SM-A750FN using Tapatalk

Title: Re: 1975 CB 400 Four - Restoration
Post by: McCabe-Thiele (Ted) on December 12, 2021, 08:29:37 PM
Nice looking restoration - I have similar coils just wondered why you did not mount them facing forwards is it to keep water out?
Title: Re: 1975 CB 400 Four - Restoration
Post by: kiki.o on December 13, 2021, 05:52:00 PM
Thanks.

Coils are not mounted yet, I need to cut the cables to length and bolt them down, but the orientation will be as shown. This is per instructions from Dynatek

(https://i.imgur.com/cf0Ikfm.jpg)

So, for Hondas, pointing down and backward.

Do you have any different info?
Title: Re: 1975 CB 400 Four - Restoration
Post by: Oddjob on December 13, 2021, 06:39:11 PM
I'd remove the front engine bracket bolts and put a flat washer under the spring washer, you'll find mounting a spring washer against paintwork will mean it removes the paint under the washer over time and thus cause rust. It was this way when Honda first fitted those bolts, always spread the force across the surface whenever possible, spring washers tend to spin as they are tightened down thus gouging the paintwork as they do so.
Title: Re: 1975 CB 400 Four - Restoration
Post by: kiki.o on December 13, 2021, 09:59:04 PM
Thank you for your remark.

I was thinking the same... The washer, spring washer , then nut. But when ordering parts and putting it together, it seems that there is no plain washer.

And that's not the only place that had me scratching my head since it doesn't seem logical.

Here's the diagram for the bike(from CMSNL, but it's the same almost anywhere)

(https://i.imgur.com/IG6sEg7.jpg)

It's a few seconds to replace it, but, should I? Any advice?

Regards,
Kristijan

Title: Re: 1975 CB 400 Four - Restoration
Post by: Oddjob on December 13, 2021, 11:11:34 PM
Odd as most of the other sohc fours came with the plain washer, still not exactly hard to add one and will save your paint.
Title: Re: 1975 CB 400 Four - Restoration
Post by: kiki.o on January 16, 2022, 05:39:08 PM
Hi all,

Some more work has been done.

I have started with the carburettor assembly.

(https://i.imgur.com/0Cdhr7s.jpg)

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

New jets, same size as the original

(https://i.imgur.com/j39AEYg.jpg)

Float mounted and set at 21mm

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

(https://i.imgur.com/GDA9WQq.jpg)

New screws and fuel lines

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

(https://i.imgur.com/i7gc9yF.jpg)

Before and after cleanup

(https://i.imgur.com/ulMDKU8.jpg)

Choke

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

(https://i.imgur.com/Jfw9mwK.jpg)

Cleaned before assembly

(https://i.imgur.com/bGS8mxC.jpg)

Oiled felt washer

(https://i.imgur.com/3A0RrSk.jpg)

Replaced rubber seals on fuel lines

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

(https://i.imgur.com/sv6aaw7.jpg)

1 and 2 are finished, need to finish up the 3 and 4 when I receive the replacement part from Canada

(https://i.imgur.com/AD8Q6Ke.jpg)

In the meantime, the coils and  spark plug cables are mounted

(https://i.imgur.com/2suJLT5.jpg)

(https://i.imgur.com/F7vF6wb.jpg)

(https://i.imgur.com/uMtSGT6.jpg)

That's it for the electrics part for now... Only horn left, and it's in the mail from Germany. Now with headlamp mounted.

(https://i.imgur.com/c6ZqYti.jpg)

That's it for now. I have tried to bleed out the front braking system, but with no luck. I have new braided lines, a new master cylinder and a new caliper.

I assume that the problem is in the MC, since there is no air bleeding out on the caliper nipple, clear fluid is bleeding out, but I cannot get the brake to build up a pressure. It does stop the front wheel when I spin it by hand, but with maybe a 1/10th of the force that it should be.

I assume that the rubber parts are old and therefore no way to build up on the pressure. While pumping the MC the black dirt was coming out of these two holes from the MC tank, as you can see in the picture, what's why I think that the blame is on the MC.

(https://i.imgur.com/mwyNMD7.jpg)

Did anyone have similar problem ? The MC is purchased from the CMSNL, but it's a repro.

Thanks for any input.

PS:Oddjob, you're right, the plain washer will be put between the spring washer and the paintjob. It's just a few minutes work.
Title: Re: 1975 CB 400 Four - Restoration
Post by: Oddjob on January 16, 2022, 07:14:56 PM
There should be a spring washer under the head of the float bowl screws as well, I always fit a flat one as well or it digs into the soft alloy and marks it.

I always wonder why 400 owners don't try and get rid of that awful choke mechanism, see if the 500/550 one will fit and ditch that awful linkage.
Title: Re: 1975 CB 400 Four - Restoration
Post by: Johnwebley on January 16, 2022, 07:32:01 PM
Hi all,

Some more work has been done.

I have started with the carburettor assembly.

(https://i.imgur.com/0Cdhr7s.jpg)

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

New jets, same size as the original

(https://i.imgur.com/j39AEYg.jpg)

Float mounted and set at 21mm

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

(https://i.imgur.com/GDA9WQq.jpg)

New screws and fuel lines

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

(https://i.imgur.com/i7gc9yF.jpg)

Before and after cleanup

(https://i.imgur.com/ulMDKU8.jpg)

Choke

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

(https://i.imgur.com/Jfw9mwK.jpg)

Cleaned before assembly

(https://i.imgur.com/bGS8mxC.jpg)

Oiled felt washer

(https://i.imgur.com/3A0RrSk.jpg)

Replaced rubber seals on fuel lines

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

(https://i.imgur.com/sv6aaw7.jpg)

1 and 2 are finished, need to finish up the 3 and 4 when I receive the replacement part from Canada

(https://i.imgur.com/AD8Q6Ke.jpg)

In the meantime, the coils and  spark plug cables are mounted

(https://i.imgur.com/2suJLT5.jpg)

(https://i.imgur.com/F7vF6wb.jpg)

(https://i.imgur.com/uMtSGT6.jpg)

That's it for the electrics part for now... Only horn left, and it's in the mail from Germany. Now with headlamp mounted.

(https://i.imgur.com/c6ZqYti.jpg)

That's it for now. I have tried to bleed out the front braking system, but with no luck. I have new braided lines, a new master cylinder and a new caliper.

I assume that the problem is in the MC, since there is no air bleeding out on the caliper nipple, clear fluid is bleeding out, but I cannot get the brake to build up a pressure. It does stop the front wheel when I spin it by hand, but with maybe a 1/10th of the force that it should be.

I assume that the rubber parts are old and therefore no way to build up on the pressure. While pumping the MC the black dirt was coming out of these two holes from the MC tank, as you can see in the picture, what's why I think that the blame is on the MC.

(https://i.imgur.com/mwyNMD7.jpg)

Did anyone have similar problem ? The MC is purchased from the CMSNL, but it's a repro.

Thanks for any input.

PS:Oddjob, you're right, the plain washer will be put between the spring washer and the paintjob. It's just a few minutes work.
You could try a back bleed,

Take the caliper off the mounting bracket, remove the piston, fill the caliper with fluid, refit piston,

Carefully press in piston, monitor the fluid in the MC,

It should purge the air,

See if it helps

Sent from my SM-A750FN using Tapatalk

Title: Re: 1975 CB 400 Four - Restoration
Post by: Bryanj on January 16, 2022, 08:30:46 PM
Most dry master cyl need to be"bled" first.
1 WEAR NITRILE GLOVES
2 remove banjo bolt at master
3 put gloved finger over outlet hole
4 pull in lever
5 remove and replace finger
6 release lever
Repeat from 4 to 6 until you feel pressure pushing your finger off.
Whilst holding lever in remove fingerand reconnect pipe with banjo. It should now bleed normaly.
Forgot to add cover painwork and anything plastic in case fluid sprays
Title: Re: 1975 CB 400 Four - Restoration
Post by: Sesman on January 16, 2022, 08:38:56 PM
Am I correct in believing it’s necessary not to pull the lever all the way, or does this only affect other model master cylinders. I’m thinking about the matchbox trick.
Title: Re: 1975 CB 400 Four - Restoration
Post by: kiki.o on January 18, 2022, 04:08:54 PM
Thanks for the advices.

Bryanj, I'll try this one, and see if it will help.

Johnwebley, I  can give it a try too, but, i do not think it's a problem at a caliper at the moment.

Oddjob, thanks for the input, I'll put the washers too. The choke mechanism stays since it's a restoration.  I have made some compromises by now(el. ignition, dynatek coils, Hagon shocks...), but I will try to keep it as original as possible.
Title: Re: 1975 CB 400 Four - Restoration
Post by: Bryanj on January 18, 2022, 04:36:00 PM
As long as they are 5ohmcoils not 3
Title: Re: 1975 CB 400 Four - Restoration
Post by: kiki.o on January 19, 2022, 09:19:28 PM
 Yes, it's 5 Ohm coils.
Title: Re: 1975 CB 400 Four - Restoration
Post by: Johnny4428 on January 20, 2022, 02:39:08 PM
Nice work Kristijan! Going to be another nice bike saved from the breakers. Thanks for sharing.
Title: Re: 1975 CB 400 Four - Restoration
Post by: kiki.o on January 23, 2022, 02:55:16 PM
Hi all,

While waiting for some spare parts, the carbs are finished. So it was time to try and to start the engine.

Finally alive after 2016.  8)

https://www.youtube.com/embed/IP7X_nHfnrE

The muffler will be replaced with the marving one, since I cannot find the OEM exhaust for now. This is the one that it came with, and is used just for starting the engine.

Best regards,
Kristijan
Title: Re: 1975 CB 400 Four - Restoration
Post by: Johnwebley on January 23, 2022, 03:06:37 PM
Very nice,

Sounds sweet

Sent from my SM-A750FN using Tapatalk

Title: Re: 1975 CB 400 Four - Restoration
Post by: kiki.o on September 15, 2022, 10:37:30 PM
Well things are finally coming to an end....

The bike is complete, registered and ridden for a 2000km now.

Here's picture today from Dubrovnik, some 600km away from home.

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

washed after the trip:

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

Now it's time to make a first service(oil, filters, lube everything...) and fine tune it.(some jetting problems, some tacho and speedo issues)

Best regards,
Kristijan
Title: Re: 1975 CB 400 Four - Restoration
Post by: Sesman on September 16, 2022, 06:22:27 AM
Nice bike. Evokes memories of my 1979 one.
Title: Re: 1975 CB 400 Four - Restoration
Post by: Oddjob on September 16, 2022, 06:59:02 AM
Why is the fuel line routed like that?
Title: Re: 1975 CB 400 Four - Restoration
Post by: McCabe-Thiele (Ted) on September 16, 2022, 10:55:38 AM
Why is the fuel line routed like that?

Slightly overlong pipe needs the heat protecting coil spring on it.
Title: Re: 1975 CB 400 Four - Restoration
Post by: kiki.o on September 16, 2022, 11:00:35 AM
I don't know, it seems like the most logical route?

what would be the correct route?

Ted, you're right, the spring is missing, I'm still searching for it. I need to leave something for the winter service  ;D
Title: Re: 1975 CB 400 Four - Restoration
Post by: McCabe-Thiele (Ted) on September 16, 2022, 01:52:16 PM
I think your route is close but due to to the excess length of the pipe it's a tad higher on the carb top. If you fit the  spring in the future it will reveal the required length.
Title: Re: 1975 CB 400 Four - Restoration
Post by: kiki.o on September 17, 2022, 11:52:30 PM
Yeah, I'll try to get the spring.

Thanks on the input.  ;)
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