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Author Topic: Project two---a CB400F  (Read 2357 times)

Offline tattoo

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Project two---a CB400F
« on: Nov 08, 2017, 16:34:23 »
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!!









Offline CrabsAndCylinders

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Re: Project two---a CB400F
« Reply #1 on: Nov 09, 2017, 02:59:23 »
Alloy rims would be a nice upgrade.
Lighter, Quicker, Faster.
ZX-14, 900F x 2, 1100F, R100, CBR600, SR500, GT500, RZ350, KZ1000 x 2, Moto Guzzi Lemans lll, CBX550, RD 350, 750 SOHC police special, RG250, TL1000R, GT750, KTM Super Duke 1290 R, Harris/Z-1, Norton 750 Commando, Green 77 KZ650

Offline tattoo

  • Posts: 167
Re: Project two---a CB400F
« Reply #2 on: Nov 09, 2017, 18:09:15 »
Indeed they would be.

Maybe for phase 2.....


Offline WhyNot

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Re: Project two---a CB400F
« Reply #3 on: Nov 09, 2017, 20:35:27 »
interested in the seat mods......may pickup/copy some of you ideals......
2006 Harley Davidson Heritage Softail
1975 Honda CB750K5 needs carb work
1974 Honda CB350F2 needs tins painted (being lazy)
1972 Honda CB175K2 roller no engine
1972 Honda CB/CL350 Engines need roller
1972 Honda SL350K2 Frame for above engine
1972 Honda CB100K2 needs kicker shaft
1990 Mitsubishi MM needs engine rebuild
1984 Dodge D50 Beater DD since 1997

Offline tattoo

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Re: Project two---a CB400F
« Reply #4 on: Nov 10, 2017, 00:07:47 »
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!




Offline tattoo

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Re: Project two---a CB400F
« Reply #5 on: Nov 12, 2017, 15:08:30 »
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.

 

Offline WhyNot

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Re: Project two---a CB400F
« Reply #6 on: Nov 13, 2017, 06:40:53 »
Looks good so far to me.

I have an extra seat pan for my 750 hanging around.....guess I'll give a go.
2006 Harley Davidson Heritage Softail
1975 Honda CB750K5 needs carb work
1974 Honda CB350F2 needs tins painted (being lazy)
1972 Honda CB175K2 roller no engine
1972 Honda CB/CL350 Engines need roller
1972 Honda SL350K2 Frame for above engine
1972 Honda CB100K2 needs kicker shaft
1990 Mitsubishi MM needs engine rebuild
1984 Dodge D50 Beater DD since 1997

Offline coyote13

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Re: Project two---a CB400F
« Reply #7 on: Nov 13, 2017, 11:25:30 »

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.
Half the fun's in the get there...

Offline tattoo

  • Posts: 167
Re: Project two---a CB400F
« Reply #8 on: Nov 13, 2017, 13:03:07 »
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!!!



Online irk miller

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Project two---a CB400F
« Reply #9 on: Nov 13, 2017, 13:18:47 »
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


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