Author Topic: 1975 CB 400 Four - Restoration  (Read 4243 times)

Offline Johnwebley

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Re: 1975 CB 400 Four - Restoration
« Reply #15 on: December 12, 2021, 08:08:12 PM »
Very nice tidy work, it's looking good

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Offline McCabe-Thiele (Ted)

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Re: 1975 CB 400 Four - Restoration
« Reply #16 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?
« Last Edit: December 13, 2021, 06:41:57 AM by McCabe-Thiele (Ted) »
Honda CB500 K1 (new pit dug out ready)
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html

Offline kiki.o

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Re: 1975 CB 400 Four - Restoration
« Reply #17 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



So, for Hondas, pointing down and backward.

Do you have any different info?

Offline Oddjob

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Re: 1975 CB 400 Four - Restoration
« Reply #18 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.
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline kiki.o

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Re: 1975 CB 400 Four - Restoration
« Reply #19 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)



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

Regards,
Kristijan


Offline Oddjob

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Re: 1975 CB 400 Four - Restoration
« Reply #20 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.
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline kiki.o

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Re: 1975 CB 400 Four - Restoration
« Reply #21 on: January 16, 2022, 05:39:08 PM »
Hi all,

Some more work has been done.

I have started with the carburettor assembly.





New jets, same size as the original



Float mounted and set at 21mm





New screws and fuel lines





Before and after cleanup



Choke





Cleaned before assembly



Oiled felt washer



Replaced rubber seals on fuel lines





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



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







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



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.



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.

Offline Oddjob

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Re: 1975 CB 400 Four - Restoration
« Reply #22 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.
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline Johnwebley

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Re: 1975 CB 400 Four - Restoration
« Reply #23 on: January 16, 2022, 07:32:01 PM »
Hi all,

Some more work has been done.

I have started with the carburettor assembly.





New jets, same size as the original



Float mounted and set at 21mm





New screws and fuel lines





Before and after cleanup



Choke





Cleaned before assembly



Oiled felt washer



Replaced rubber seals on fuel lines





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



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







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



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.



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

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Offline Bryanj

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Re: 1975 CB 400 Four - Restoration
« Reply #24 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

Offline Sesman

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Re: 1975 CB 400 Four - Restoration
« Reply #25 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.

Offline kiki.o

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Re: 1975 CB 400 Four - Restoration
« Reply #26 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.

Offline Bryanj

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Re: 1975 CB 400 Four - Restoration
« Reply #27 on: January 18, 2022, 04:36:00 PM »
As long as they are 5ohmcoils not 3

Offline kiki.o

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Re: 1975 CB 400 Four - Restoration
« Reply #28 on: January 19, 2022, 09:19:28 PM »
 Yes, it's 5 Ohm coils.

Offline Johnny4428

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Re: 1975 CB 400 Four - Restoration
« Reply #29 on: January 20, 2022, 02:39:08 PM »
Nice work Kristijan! Going to be another nice bike saved from the breakers. Thanks for sharing.
1952 Cymoto on Triumph bicycle.
1961 Matchless G3
1974 Honda CB550K1. Running resto,
1978 Honda CB550K3.
1999 ST1100 Pan European 50th Anniversary.
1975,1980,1984,1986 Honda C90’s
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