A 1975 CB400F high mileage complete engine rebuild

[stl360+450]

A vintage bike night here in the US typically happens at a venue with a large parking lot and all makes of vintage bikes are welcome. There will often be food/drink available for purchase and people walk around admiring old machines, some freshly polished and very shiny and others heavily modified and/or rough around the edges. Prior to the pandemic, there was a thriving summer-monthly event in my area that brought out many old Hondas and other Japanese brands as well as Harley, Indian, BSA, Triumph, BMW, Moto Guzzi, and even one Vincent (Black Shadow).

Your 400F (or any of your other bikes) would definitely get noticed and appreciated at that sort of event, where most of the attendees have a keen interest in vintage motorcycles. It hasn't been the same since the event was resumed last year, but hopefully it will regain its old form at some point.

 

[ancientdad]

A vintage bike night here in the US typically happens at a venue with a large parking lot and all makes of vintage bikes are welcome. There will often be food/drink available for purchase and people walk around admiring old machines, some freshly polished and very shiny and others heavily modified and/or rough around the edges. Prior to the pandemic, there was a thriving summer-monthly event in my area that brought out many old Hondas and other Japanese brands as well as Harley, Indian, BSA, Triumph, BMW, Moto Guzzi, and even one Vincent (Black Shadow).

Your 400F (or any of your other bikes) would definitely get noticed and appreciated at that sort of event, where most of the attendees have a keen interest in vintage motorcycles. It hasn't been the same since the event was resumed last year, but hopefully it will regain its old form at some point.

Yes it would. I go to my local weekend bike hangout on Sunday mornings during the cooler months, mostly modern bikes but a few vintage models now and then. My 450 has been the only DOHC 450 every single time I ride it there, I've never seen another one of any year. There was a Vincent Black Shadow once (unfortunately owned by a guy who does little to preserve it properly) and some older Guzzis and Ducatis too. I went to bike night in Greenville when we visited upstate South Carolina last October and there were some vintage bikes there then, like a beautiful Kawasaki H-2 and a very nice VF750F

 

[jensen]

Somehow I can't turn my pictures, I took them with my android phone, normally I use my apple.

Fixed it, I did share the pictures in WhatsApp, synced with my computer and copied them out WhatsApp into the forum, it works !

Tonight I started to add parts to the frame, beginning with the air filter housing, including all the electrics, puzzling it is. I made a lot of pictures before taking apart, so I will work it out.....

 

[ancientdad]

Yes, when you've had a bike apart as long as you have it can be quite an effort to remember so pictures are a must.

 

[jensen]

Pictures from 2008, while taking it apart:

 

[jensen]

This night the electrics, first things first, make a good ground. Engine to frame, frame to battery (-), ignition coils to frame, frame to wire harness, engine to wire harness. All checked with a resistance meter, al below 0,1 Ohm. No electric gremlins on this bike!



Mounted coils, cleaned, tested en connected.



High voltage lines and plug caps.



Wire to the engine ready for connecting



I checked with the old pictures and the images of the FSM's, this is more or less how they left the factory. I say more or less, because I think that not all bikes wired in the exact same way. I have seen pictures of new bikes with different routings of wires (in details), I think that the people working at the factory did not al do it the same way.

Electrics done, now only connect the users like winkers, lights, speedo / rev counter. I cleaned the harness years ago before putting away, I just dropped it in.

Next is the swing arm and front forks, but that will take a while since I have a few busy weeks at the company ahead.

 

[stl360+450]

That green-white-black sticker in the last photo is from the factory? I've never seen anything like that before.

 

[LongDistanceRider]

Looking great Jensen.

 

[Maraakate]

Your attention to detail is awesome. I try to do the best I can, but could never go all out like you do even if I tried. Really impressive work.

Also, a bit OT but my girlfriend she's 3rd generation in the US from NL. Her grandparents moved from NL to US back in the 1960s. And it's pretty cool that CMS is also located in your country. I guess the Dutch have an increased appreciation for the vintage Japanese bikes!

 

[jensen]

That green-white-black sticker in the last photo is from the factory? I've never seen anything like that before.

Yes, from the factory, the colours on the sticker correspond with the wire colours, same as on the winker relay (aluminium tube in post #156, last picture). There the terminals are marked with paint in the wire colours.

Your attention to detail is awesome. I try to do the best I can, but could never go all out like you do even if I tried. Really impressive work.

Patience is all it takes, and studying pictures, mine as well as in the manuals and books.

Also, a bit OT but my girlfriend she's 3rd generation in the US from NL. Her grandparents moved from NL to US back in the 1960s. And it's pretty cool that CMS is also located in your country. I guess the Dutch have an increased appreciation for the vintage Japanese bikes!

Good to hear. Yes, CMSNL is located in the Netherlands too, I ride by the building almost every day to work.

 

[Maraakate]

Patience is all it takes, and studying pictures, mine as well as in the manuals and books.

Patience is a virtue; one that I lack in some things more than others. A total rebuild and proper restoration like yours takes extreme patience and discipline so hats off to you.

 

[jensen]

Last week some progress:





Top and bottom bearings mounted



NOS T-piece (old one was worn /cracked), ready for assembly



Swing arm mounted, including shocks and passenger steps



Battery tray and air filter housing ready for receiving battery and air filter



Brake, brake switch and kick started mounted

 

[ancientdad]

It will look like it should be sitting in a Honda showroom when it's finished.

 

[jensen]

Thanks for the compliments, AD, but this will be one of my daily riders next to the K0, K1 and CB72'62.

btw, putting the engine in the frame took me 30 minutes, routing the cables properly according to Honda took me two nights of working.



Talking about showroom, below the ad for the CB400f, in red.

 

[ancientdad]

And I didn't mean it should be in a showroom, I know you ride your bikes. But it will look like it could be in a showroom if they still sold them. If only they still sold new bikes of that style instead of the jacked-up-rear-end road race styled sport bikes today. I wish the trends would change, I'm tired of seeing everything looking the same.

 

[stl360+450]

It's looking really good! Thanks for sharing the old advertisement - those are always interesting to me.

 

[jensen]

And I didn't mean it should be in a showroom, I know you ride your bikes. But it will look like it could be in a showroom if they still sold them. If only they still sold new bikes of that style instead of the jacked-up-rear-end road race styled sport bikes today. I wish the trends would change, I'm tired of seeing everything looking the same.

Ha, I know what you mean. Yes, indeed it will be in showroom condition, except for the tires. BT45's underway, no classic profile here.

I didn't made it late yesterday evening, because I wanted to walk early in the morning, so no real progress except that the rear mudguard is now in place and additional time spend on wiring and routing.
However, this morning I got up at 05.00, and had a nice walk. Made some pictures too, it's fascinating how good the camera's are on a modern mobile phone. Even straight into the sun the camera is performing well and produces good images. I did this with manual settings, with auto-settings I was less successful.







btw, this was the old T-piece, if you look closely, you can see it had a hard life. No short cut's taken here, found a NOS one cheap..



btw, this is the thread and profile on a BT45, it's not that disturbing to me (old picture)

 

[ancientdad]

Cool mudflap.

 

[ballbearian]

Peaceful scenes of morning fog.
In the bicycle world, a fork stem like that could sometimes be saved by laying a knurl on the base to increase the diameter for lower bearing fit, in addition to some steel epoxy.

 

[jensen]

Cool mudflap.

Thanks, yes indeed and mandatory in the Netherlands. Most people did throw the mudflap away, the PO of this bike didn't. In the last 12 years I saw only 3 for sale, and since nobody wanted them, thus low priced. Guess who has now 3 spares .

In the bicycle world, a fork stem like that could sometimes be saved by laying a knurl on the base to increase the diameter for lower bearing fit, in addition to some steel epoxy.

Yes, but repairing an object like this, compared with the price of a new one and the risk taken by repairing, I prefer new, especially considering that if it breaks, it would be very difficult to keep the bike on the road at high speeds.

 

[ballbearian]

Yes, but repairing an object like this, compared with the price of a new one and the risk taken by repairing, I prefer new, especially considering that if it breaks, it would be very difficult to keep the bike on the road at high speeds.

Correct. I hope I didn't miss anything, all I noticed was the lower bearing mounting area. Still, you are prudent to not take chances on a machine much heavier and faster than a bicycle. An experienced cyclist would feel a headset (steering bearings) that was mal adjusted almost before mounting up.

I suppose old school repair processes are something that interests me. I have very much enjoyed your assessment and decision making on the various components.

 

[jensen]

The lower bearing ring was cracked too.

 

[ballbearian]

The lower bearing ring was cracked too.

I may foolishly champion lost causes, but that's a lost cause. That is why the seat galled.

 

[jensen]

This is how it came out when I disassembled the steering section. Completely worn and cracked. How it happened no one knows. The crack was located at the back side, right in the centre. Since it cannot turn around the pin of the T-piece (press-fit), it must have been an impact in a straight line. I rule out that wear is the reason for the damage, just like manufacturing problems.

However, an assembly error could have caused it, first the crack, and later the square balls due to the crack. The dimples on the rim can only be seen around the crack, the opposite site of the rim is ok.

 

[ballbearian]

This is how it came out when I disassembled the steering section. Completely worn and cracked. How it happened no one knows. The crack was located at the back side, right in the centre. Since it cannot turn around the pin of the T-piece (press-fit), it must have been an impact in a straight line. I rule out that wear is the reason for the damage, just like manufacturing problems.

However, an assembly error could have caused it, first the crack, and later the square balls due to the crack. The dimples on the rim can only be seen around the crack, the opposite site of the rim is ok.

The inclined angle of steering bearings causes wear on the front of the lower stack and the rear of the upper. Hard to say what caused that. A cracked ball can do a lot of damage.

 

[jensen]

Yes, agreed, but there was no evidence or residue of a cracked ball, some were more square(d) then others, but no more than I expected after 102.000 km's.

 

[ballbearian]

Wow, 102K km, you've well earned your destructive testing merit badge.

 

[stl360+450]

Do the pictures in post #162 tell us you're using tapered bearings rather than the standard ball bearings? (I've yet to rebuild a steering stem.)

 

[jensen]

Do the pictures in post #162 tell us you're using tapered bearings rather than the standard ball bearings? (I've yet to rebuild a steering stem.)

Yes, I do use tapered bearings. In this case the distance between the upper and lower steering stem pieces are not so critical as on my CB450 K0.

 

[stl360+450]

Is that pesky job continuing to interfere with the final assembly of the 400F? I'm looking forward to the next installment on this thread, when you have time, of course. I hope all is well.

 

[jensen]

Yes, all is well, and I enjoyed a 3-weeks holiday with my family. Just got back yesterday, today back to work....

Ordered some small parts which I expect to be delivered end of the week.

 

[jensen]

Maybe you all knew, but I use this method to install those nasty springs:



Put one side of the spring in a vice, bend it, and push a this washer between the wire, then bend to the other side and add another washer, and repeat until the length is adequate to place without hassle. After placing, take the washers out, one by one.

 

[stl360+450]

Your picture makes it look easy, but I have yet to manage it that way. The center stand spring on my 450 needs to be replaced (too weak), so I'll have another go at it.

 

[jensen]

It is easy !, never fails. I my case, the length was too much, it was loose when putting in.

btw, I will add some pictures of the whole bike soon. Rear wheel is placed, main stand is assembled, brake-torgue rod is places, as is the rear brake rod, break switch and some small parts. The generator is in place, as is the points-plate, the ignition (static) is timed, and connected to the coils. Still waiting for parts from CMS before proceeding with the front side.

 

[stl360+450]

I think when I tried it I didn't use a vise and was putting pennies between the spring coils rather than washers. I've been saving up for the job and I think can afford to use nickels for the next attempt, so hopefully it will go better with thicker inserts.

I'm looking forward to the next round of pictures.

 

[jensen]

Thinner is better, thicker is more difficult, especially with stiff springs. however, you'll need more of them. A little oil, bend and it they will slide in (that sounds awkward ?) Anyway, a washer has a hole in the middle, just need a small screwdriver to get them out.

 

[jensen]

Picture of the result after taking out the washers



main stand shaft in place, main stand is working fine, and it is secured.



Oil pump is in place, generator too. Wires have to be connected, including the neutral switch wiring.



taken from the other side, brake pedal is in place and adjusted



Torque arm installed and secured on both sides



Interesting adjuster detail picture, hence the fat nut used by Honda.




Everything in place, secured and adjusted. The hollow brake torque rod is filled with tektile to withstand our winters and rainy days.



rear shaft secured with a too large clip. Smaller one is coming soon I guess. Fresh tires too (BT45)

 

[ancientdad]

Quite a bit of rear brake adjustment already used, as well as chain adjustment. I'm sure you have new rear shoes and chain to install.

 

[jensen]

Chain is not in yet, so it's set in a random position. However, brake shoes are ordered, but still inbetween. I didn't want to wait, so I moved on, taking it apart when the front fork is in. There is still 2 mm of room (read wear), but it's better to replace before I take out to the streets.

During the winter I have to re-chrome the rear axis, since it was lost while the other stuff was at the plater. Same with the side stand spring and bolt, forgot where I put if 12 years ago, but found it after I got everything back from the plater.

 

[stl360+450]

Thinner is better, thicker is more difficult, especially with stiff springs. however, you'll need more of them.

Thanks for the tutorial, Jensen. My new center stand spring arrived today and I was able to install it using a bunch of pennies and one dime. This repair was long overdue -- my stand often banged around when I would encounter speed bumps or pot holes.

My technique still needs refinement and if I had enough thin washers it would have saved me the trouble of picking up all the coins from the floor after I extended the stand...

Addendum: The stand behaved much better on the speed bumps in my neighborhood this morning. No clanging and I took them at the speed limit rather than slowing down.

 

[jensen]

Slowly the bike comes together. After the rear wheel and brakes, the front was next on the list.



Everything mounted and ready to take the fork tubes, however, first the wiring...



Starting with adding the main switch and go from there.



Replaced the rubbr boots for the speedo and rev-counter



After almost 50 years, still looking good...



Got started with connecting the wires from the switches on the main harness

 

[stl360+450]

Very nice. I totally agree that everything looks great, especially after 50 years in service.

 

[ancientdad]

When Honda wiring is on a bike that has been stored inside for most of its life, it's amazing how good it still is after that long. Leave anything outside unprotected for long enough and it will get brittle and destroyed, but that wiring looks as good as any you'd expect to see on a bike less than 10 years old. And that also speaks to the level of quality used on the bike to begin with.

 

[jensen]

I cleaned all the wiring step by step before installing. Using silicone for the plastic sheeting (let it soak on a closed bag for a week or so, make sure you just add silicone to the wire's not on the tape), makes colours bright again, dirt and grease disappear when rubbing with a cloth. Then spay silicone in each contact and clean with pressed air. When dry, I spray petroleum jelly (Vaseline) in the tubes, and dry again with pressed air. After that I make sure the fit of the bullit is tight in the contact by altering the diameter of the contact. I always use a little bit of acid-free pure white Vaseline to grease the bullet contact before pushing together.

It took me at least 10 hours of work for the cleaning alone. I repaired a few contacts, that took another 2 hours. On the HT forum I described the process which I did with my bomber. I can copy the info to this forum, I still have the pictures of my Bomber thread on HT.

The quality of the Honda wiring is good, very good. The most damage on wiring is done by UV (sun) and humans (not particularly in that order).

 

[LongDistanceRider]

A separate thread on reviving the wiring harness would be good to post if you don't mind.

 

[Richard Pitman]

+ 1 on the springs tip. I struggled to replace the spring on an up and over garage door until it dawned on me that I could pack the spring out using UK 2 pence pieces, back when they were valid currency. Thought at the time that I'd made an astounding discovery, nothing new under the sun I suppose.

 

[ballbearian]

+ 1 on the springs tip. I struggled to replace the spring on an up and over garage door until it dawned on me that I could pack the spring out using UK 2 pence pieces, back when they were valid currency. Thought at the time that I'd made an astounding discovery, nothing new under the sun I suppose.

As an overhead door tech, normal spring replacement is done with the door fully lifted, then the springs are slack. I'm talking side springs type, not center mount torsion bar type. Be careful, a lot of kinetic energy stored in charged springs. I hope you ran a safety wire inside the length of the springs to prevent it being launched like a javelin through the walls of your house, if it should break.

 

[jensen]

Yesterday evening I spend the whole evening to route cables, wires and hoses. I'm a OCD guy when it comes to routing, if it's not good enough, I start over again. I have pictures enough, but the FSM doesn't show the right or clear pictures, drawings and information compared to the possibility's and issue's. So, puzzling it is..




It's always looks chaotic, especially when you have a lot of loose wires.




But after a while chaos will make room for structure and discipline. I really like to do this without the headlight shell and without the front fork legs in place. This way it's easy to turn the steering back and forth to see if cables, wirer and hoses move freely without tension etc. As you can see, I replaced the old rubber brake hose with new, steel braided hoses and new banjo's. The disc brake of the Cb400f is very disappointing when it comes to braking, so every step to make that better is a good step forward.



And if everything is more or less in place, adding stuff like winkers is a pleasure.


Here you see the problem with old rubber, unfortunately, a hard to get part, so still looking for one.

 

[stl360+450]

Those close-up pictures of the wiring harness are very compelling. I haven't decided whether or not to use the original harness for my 350 project, but I think you've motivated me to try cleaning it. I may even creep over to HT to read your old thread. Are the colors of your stator wires as crisp and bright as those around your headlight bucket?

It didn't occur to me until you mentioned the disc brake that none of your CB450s or other Honda Twins have one. Do the steel braided lines outperform a new set of rubber lines or is it more a longevity consideration (to avoid swelling)? Did you source an NOS caliper and piston or rebuild the originals?

Is this band at CMSNL possibly the one you're trying to find?

 

[jensen]

Yes, it is. Hmm, last time I checked (few months ago) it was unavailable, thanks....

I checked the HT-forum, but unfortunately I removed all important information. I have a copy of those pages on my back-up disks, including the images. I'll look into that soon. I always use the original harness, no matter what it's status. there are always good usable parts. The only thing you need is parts and patience. In the past years I bought / got some boxes full of used Honda wire harnesses from local scrap-yards and took the tape from it (easy when you use silicon on the tape).

Are the colors of your stator wires as crisp and bright as those around your headlight bucket?

sort off, here a picture:



I wasn't happy with the degree of deterioration, so I replaced all wires from the generator by better ones. These contacts are very important, and should have a very low resistance, since you will loose a lot of power.

All colours are in there, including good bullet contacts and fuse holders. During the last 50 years Honda used the same colour for each function, only the functions grew, so more complex coloured wires in later harnesses. The basic colours remained, so plenty of them for example, winker wires are always light blue and orange, it never changed.

It didn't occur to me until you mentioned the disc brake that none of your CB450s or other Honda Twins have one. Do the steel braided lines outperform a new set of rubber lines or is it more a longevity consideration (to avoid swelling)? Did you source an NOS caliper and piston or rebuild the original?

Indeed, the only (Honda) disc brake bike in my stable. Yes, I replaced the hose, after 40 years of service it's mandatory due to safety reasons. And if you're on to it, a steel braided hose is always preferable. Yes, I did a full rebuild in the brake caliper, as well on the brake pump. Still, it's not very good. The ratio between both pistons is not optimal, actually, I need a smaller diameter piston on the brake pump, or more pistons in the brake caliper.

I'm busy with the second solution, and busy with a Brembo caliper, with two pistons instead of one. This caliper is used on many classic Italian bikes. Since these calipers can be ordered as left or right, it's possible to use them in front of the fork, just like the original.



Another reason for using this caliper is the way they're build. There is not much room from the centre of the disk to the spokes, this caliper just fits. Since I'm working at a machine builder, it's not a big issue to make a caliper holder that fits directly on the original fork. Another possibility is to go to two discs set-up of the CB500 550, but that's not what I had in mind.