ON THE ROAD!!!!! Project two---a CB400F

tattoo

New Member
Hi again all,

Bought this '75 CB400Four back in the spring of 2016.




It's in real good condition, but I have no real overarching urge to do the 'restore to factory' thing...it's just not something I'm interested in.

Two owners (one of whom is a friend and the other owner is a friend of his...). Just over 18,000 miles, near as I can tell everything's original except the muffler, the mirrors and the levers.

It sat happily in the garage since it came home, but got it started (but not idling) back in August 2017 and safetied in September.

The goal is to:
Not alter the frame in any way
Ensure that it remains recognizable as a 400Four
End up with a machine that I can have some fun on twisty roads with without needing to do anything license threatening.

Playing around with a picture in MS Paint, my imagination sees it becoming something that might look like:


Of course there is an abundance of information/opinion available at our fingertips these days, but I think the info that I want to base decisions upon consists of: [paraphrasing]--great little bikes, weaknesses are the suspension and brakes (surprise, surprise). There's also the cam chain adjuster issue that will be addressed as best as I can in due course.

So:
Sourced a rebuilt and almost complete CB500Four front end (35mm versus 33mm forks) that's been upgraded with emulators and modified to run dual disk with All Balls head and wheel bearings.
And I'm still looking for some shocks for the back.

Hope to keep the signature 400Four bits like the exhaust headers, the tank (hopefully getting away with the original paint too), and I'm working towards using a reshaped 400Four seat.
Have bought slightly wider rims front and back, removed the passenger footpeg brackets off a second swingarm that I bought, and will downsize the lighting, gauges and fenders.
Want to also look into running electronic ignition.

The 'progress' so far feels like it's been all over the place, and I have lots of pictures of the trying and testing steps that I've done so far, but it feels kinda weird to post them in this thread.

That said, a (in random order) a sprinkling:

Spare swingarm before and where it stands now
CB500 Four front end bits
Tank showing two little dents (that vertical line under dent 2 is actually just a shadow) that I'm hoping to undent
Spare 400 Four seat that is undergoing reshaping surgery
The left side rearset (from TTR400, bought barely used off kijiji...)
That exhaust....












And, as with 'project one', there is of course a budget, a desire to learn more about how motorbikes come apart and go back together, and that resulting benefit of trying new things.

Stoked!!
 

whynot

~~~If it ain't raining, I'm riding~~{iii}?~~prost~
Re: Project two---a CB400F

interested in the seat mods......may pickup/copy some of you ideals......
 

tattoo

New Member
Re: Project two---a CB400F

No worries sir!

I'll post pictures of the seat mod progression. I think there's a little more to come off the back of the seat pan, but will likely spend some time taking a little off the foam first. Essentially will scoop out the rider position a little, will likely add back a layer of something to give me back some of the support there (open to ideas!!!), and will shave off the passenger position down to that horizontal plane. I think the key will be patience and doing a little at a time, resetting the pan/foam on the bike, standing back and staring.

Hack saw blade, angle grinder with a flap disc on it, earplugs in and shop glasses on....what could possibly go wrong???? Ha!
 

tattoo

New Member
Re: Project two---a CB400F

Well, learned a little bit this morning about the topic of seat foam shaping.

Starting with an angle grinder and a 60grit flap disc then moving to some 80grit paper on a block I slowly got from:



to:







Told myself to stop, and allow some time to stare to see if any more needs to be done. Part of me thinks the raised rear portion should be a little shorter in length....so that either requires the front lower portion to stretch longer of the ramp to me less steep. Hopefully some staring will help me see the answer.

Thankfully too I'm not a big guy, so the slightly lowered seat height and rearset pegs are gonna work out just fine I think. The seat itself even with some foam removed continues to provide support and (sport bike-ish) comfort.

Essentially just eyeballing the total seat length- I'd like it to be a little shorter out back, but don't want to expose / draw attention to the open space between the seat edge and the fender / frame rails either.
 

whynot

~~~If it ain't raining, I'm riding~~{iii}?~~prost~
Re: Project two---a CB400F

Looks good so far to me.

I have an extra seat pan for my 750 hanging around.....guess I'll give a go.
 

coyote13

New Member
Re: Project two---a CB400F

tattoo said:
Told myself to stop, and allow some time to stare to see if any more needs to be done. Part of me thinks the raised rear portion should be a little shorter in length....so that either requires the front lower portion to stretch longer of the ramp to me less steep. Hopefully some staring will help me see the answer.
First of all, patience is a lost art so kudos to you on stopping while you're ahead. Second, if you shorten the rear fender, it will mesh better with the length of your seat and you shouldn't have to do any more trimming there.
 

tattoo

New Member
Re: Project two---a CB400F

Hey there WhyNot----please----I am NO expert here, but if you take the flapper disk on an angle grinder to the seat foam....it does work, but try to just graze the foam with each pass - it's easy for the disk to bite too hard.

Also, (and I can't logically explain why) but if you are working in one direction across or along the foam, you'll get to a point (almost on the "far side" or the at the very back or front) where that next swipe will bite too hard. Trick is to flip the seat around and come at that area from the other direction. No idea why...

And Coyote13---the goal is indeed to bob that rear fender off a bit----it will be a final step, but I'm thinking if it only being 3 to 4 inches long behind the seat (depending on what tail light does in there as well).

I did go at the foam again this morning....reduced the angle of the ramp which moved the start of the rear plateau back, and made the rear portion more of a dome shape which also removes "mass" making it smaller.

(pardoning my less than spectacular photo-shop (actually MS Paint) skills) Where I'm (loosely) trying to go:


Where I'm at now:


Another angle:


More staring required---(haha) but I think there's more still to come off the rear portion of the rider's seat area. Smoothing out the angles and a more dome shaped rear portion should also make the upholster's work more enjoyable too....

Gettin' there!!!
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
Project two---a CB400F

A sanding disc on an air sander works better than a flap wheel on the grinder and doesn’t bite so much, especially if you keep the rpms lower. As strange as it may seem, foam has a “grain” like wood that does have direction


Sent from my iPhone using DO THE TON
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
Re: Project two---a CB400F

Yeah, it's how the foam is poured into a mold. If you've look close at the insulation foam you get at the hardware store, you can see it.
 

tattoo

New Member
Re: Project two---a CB400F

After some more staring and considering some other's input, we went for round 3 of sanding.

Taking the rear's dome shape down to a flatter surface accomplishes a couple of things -- continues to reduce its visual mass, and allows some of the gas tank's more angular lines to be picked up by the seat. The rear portion's sides were also shaved more to be flatter.

I think we're there...









woot.
 

tattoo

New Member
Re: Project two---a CB400F

Oh look!!!! An engine almost ready to be removed from a frame!!! wow!!!!



Still poking at the seat foam as well....the left/right rises to the rear portion aren't totally symmetrical....so gotta run to the HW store for more 80grit.

The seat pan got some paint on it though.



And playing around with some 0000 steel wool and some metal polish to see where I can get them header pipes to..

 

tattoo

New Member
Re: Project two---a CB400F

Drained the engine oil and removed the filter...

Wonder when this was last cleaned....




Pulled the sprocket cover off too. That all should clean up nice

Pulled the slightly modified and primed spare swingarm off the shelf too and shaved the chainguard mounting stuff and filled the one bolt hole. Got some sanding to do, then will spray again with primer. Also figured I'd install the shock bushings prior to painting (I know....will have to do some masking...), and will tackle the pivot bushings next (bought some bronze ones to replace the plastic OEM units).

Gotta find a helper now to get that engine out of that frame!
 

tattoo

New Member
Re: Project two---a CB400F

Yup. But there is some sort of satisfaction in cleaning up old parts eh....kinda therapeutic.

Couple of small to do's tackled this week.

The rear wheel will be taken apart to lace on the 2.15 rim, but in the meantime cleaned up the sprocket side with some 0000 steel wool....I'm loving this stuff!!


Got the rear shock bushings in.


And the swingarm pivot bushings in


They will be masked up when it comes time to paint.

And cleaned up the dust covers. They looked like they had some black paint on them----were they black from the factory by chance?


And a couple of items on the lower triple. Removed the steering lock key switch, to provide a spot to eventually attach a bottom mount headlight, did a little sanding to clean up the surfaces a bit, and sprayed with some satin black.
 

tattoo

New Member
Re: Project two---a CB400F

Pulled the engine out last night, and got the frame down to a "starting point" this morning.





There are so many little scratches and marks on the frame....(well, 42 years worth of the I guess eh?). One of my goals for this bike is not to modify the frame in any way....and that (to me) includes messing with the factory paint. Really hoping that once it's a motorbike again that the frame 'imperfections' will be almost tiny contributors to "character'. They will, right?
 

tattoo

New Member
Re: Project two---a CB400F

Got the front rim back from the powdercoater. Not an exact match to the already coated rear, but close enough I think.



Tackled the front wheel lacing puzzle, and after discovering a false start with the inner spokes, got back on track





Got the All Balls races in



Had to reshape the CB500 Four's lower triple so that it would clear the 400F frame's steering lock tab, repainted, and installed it all, and ran the forks up in as well.



 

tattoo

New Member
Re: Project two---a CB400F

Feels like I'm bouncing around like a frantic squirrel in the Fall...finding, collecting and stashing away nuts for the winter.

Trued up the front wheel, got the rear tire removed from the wheel, disassembled the rear wheel.



Rear hub will get cleaned up....


Managed to save and polish and reuse the spokes on the T500, but these are too far gone. Ordered up a set of OEM this afternoon from the local dealer. Should be in tomorrow.


In going through and cleaning up my front brake pieces, I notice that my two caliper brackets have different finishes...even after some polishing.....so....let's use up some of that Buell XB silver paint that I had left over..




What else can I get into? Have some bits and pieces coming from 4into1, and got some o-rings from my local fasteners store so dug out the carbs and started getting organized to reassemble the bottom halves.

Before and after....


Tried some CRC heavy duty degreaser on the rear engine cases....wow....grime comes off quite easy with this stuff!





Also cleaned up and painted the engine brackets. Will have to scrape away some paint on that rear one for the battery ground connection on re-assembly.


And I think I need to replace the head gasket, so started carefully and slowly disassembling the first engine I'll have worked on....baby steps!


Dropped off my tank with the guy who painted my T500 tank. He's going to have his dent removal guys look at a couple of small dings in the tank---hoping to get them out without too much damage to the paint. Ideally, will save it and re-freshen it up a little.

And I have an OEM CB550 top triple and 400F seat cover coming my way too, so looking forward to continuing to build up the front end, and get my seat components to an upholsterer.
 

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