Topic: CB400F road race project

[HondaCB400F]

My new project is to build a cheap race bike so I don't risk crashing my nice (and valuable) NSR250 that I would love to continue riding on track days but don't want to risk anymore.  I've always had 400F's around here and have several parts bikes and lots of parts, so it's a no brainer for me to put one of these together.  Actually I would have done this years ago had I known there was such a thing as "track days" and you didn't have to be a full fledged racer dude to get on a road course.

The starting point is a Varnish blue '75 that a friend bought on Ebay at least 8 years ago.  He found a nice non-running, no-title bike.  We had it running in no time but he was stuck because he never bothered to find the title.  I still liked it though because at the time you could put a set of carbs on ebay and get around $100 for them and it had a halfway decent tank.  I had never found a decent Varnish blue tank but my first 4 cylinder bike was a Varnish blue 400.  We put it together with parts I had and got it running, but he never tried to find the owner that had the title or get a new title for it.  The bike was parked for a long time and I eventually bought it to get the tank and the other good parts from it like the muffler, NOS bars and switches, original Bridgestone Super Speed front tire, and working footpeg that stays folded when you need to kickstart it.  

Tonight I pulled it out of the garage and started stripping off everything that I don't need for the track.  Off came the rear fender, lights, airbox, all wiring, inner fender, sidecovers, and speedo cable.  A friend rode by and saw me working in the driveway and stopped to talk so that's all I got done.  It was neat having a KZ1000 next to my 400 - that sure shows you how small these bikes are!

Here are the pics so far:

Before:



In progress 07/27/09:



Craig

[HondaCB400F]

Tonight I removed the gauges, front fender, and handlebars.  Since I haven't figured out what to do with my bar placement yet, I flipped them upside down and end for end and they really aren't half bad as mini clubmans.  Due to the front master cylinder/lever combo though, I can't have them pulled back the way I want because it hits the fork.  Maybe somebody has tried this before and has some advice.  Pics to be posted later.

Craig

[FREQUENCY 24.7]

sounds like you and i are on the same path. i too am building a track bike out of a 400 4. i will keep an eye on the progress and interject if i know the answers!

[HondaCB400F]

Where are you located?  And what do you think you're doing to yours?  (engine mods, exhaust, bars, tires, seat, etc)

I was making great progress till work caught up with me.  I'll be back on it again tomorrow and Saturday though.

Craig

[HondaCB400F]

Tonight's progress:







Added a set of "drag bars" I already had (want to use clip ons when I weld up a set of rear sets), removed seat lock which I had forgotten about, and removed the exhaust.  I have a blacked-out header and (I think) Jardine muffler that I ran on a street bike a LONG time ago.  That pipe sounds sooooooooooo sweet I have to use it on this thing.

Craig

[Ecosse]

sure gonna follow this one. love these bikes!

btw: if y'all wanna unload 400f bars i'm listening...

[FREQUENCY 24.7]

Where are you located?  And what do you think you're doing to yours?  (engine mods, exhaust, bars, tires, seat, etc)

I was making great progress till work caught up with me.  I'll be back on it again tomorrow and Saturday though.

Craig

im in louisville ky, im running a modern yosh exhaust mated to the stock headers, billet clip ons, a ducati solo race seat, billet rearsets, brembo front radial master cylinder with ebc brake pads, and the removal of nearly everything possible including the starter, center stand, chain guard, fenders, lower exhaust mount, rear passenger pegs, etc.

As far as engine goes, I just moved my needles up a notch to compensate for the exhaust. I have very low miles on my bike and dont think im going internal for awhile. For the life of me, I cant get pod filters to run right, Ive been told 110 main jets but havent tried them yet, so far the only thing she likes is the stock airbox and filter! take it off her and she will run like old people #$%*.









looks like your on the right track, i cant bring myself to remove all the lights just yet, i still drive it on the street, but perhaps soon.

[HondaCB400F]

That's a sweet looking 400 you have.  Any Honda 4 will take a puke if you even remove the air filter, let alone the box.   

Does anybody have jetting/needle setting recommendations for the various combos on a 400/4, especially open carbs with a pipe and stock header?

Thanks,
Craig

[FREQUENCY 24.7]

That's a sweet looking 400 you have.  Any Honda 4 will take a puke if you even remove the air filter, let alone the box.   

Does anybody have jetting/needle setting recommendations for the various combos on a 400/4, especially open carbs with a pipe and stock header?

Thanks,
Craig

ditto, i cant find definitive answers on that either.

[tsflstb]

Good luck with the jetting.  I actually had to raise the needles when going from a dirty air filter to a clean one.

You can take 50 lbs. off the stock bike easily and really surprise a lot of modern sportbikes.  Losing that weight makes even the stock suspension work a lot better on the track.  With the 6 speed, you can add a couple of teeth to the rear sprocket to accelerate faster and still have plenty of top end.  I'd keep the engine pretty much stock until it's worn out.  If I had it to do again, I would have laced up some 17" wheels instead of 18".  Then you can run 125 or 250 GP slicks.  The Bridgestone BT45s have worked well at the track for me, but I'm no Valentino Rossi out there.  Really the stock bike is very capable at an intermediate pace without too much modification.

I probably went a little overboard on mine, now I feel like you and your NSR.  I'm debating selling it for something more "crashable". 

[HondaCB400F]

Wow, that is a SWEET looking 400!  And on the track too.....that gets me pumped up to finish mine!

For stock rims, what size tires do you recommend?  And where are you guys finding those cool exhausts that look like the old Yosh pipes??

Thanks for the post.
Craig

[Ecosse]

check out 400FOURstore.com

[Industrial Rat400f Killer]

check out 400FOURstore.com

Yes there is very many great things there. I lightened my bike as much as I could, put on Hagon shocks and added the preload adjusters from the 400 store. I've never taken it to a track but I out corner most of my buddies with 500-750's. They pull ahead on long straights though.
I have stock header, harley sportster stock muffler and pods. The low rpms are unresponsive but once I'm in the power band it's performs pretty good.

[HondaCB400F]

Tonight I tried to fit a FZ600 wheel - nice looking rim with a newish tire and dual discs.  No go - the hub is too wide.  Bummer

So then I took my favorite 400F exhaust off of the first 400 I got and cleaned it up and repainted it.  While I was waiting for the hi temp paint to dry, I started hacking at a junky seat I had but all I got done was get the cover off.  The paint was dry enough to put the header and pipe on the bike.  Then I switched the nice blue tank for a different, well used '75/76 one in need of paint.  When I started this project I remembered that I had the tank on the shelf so I already bought some yellow and clear Krylon thinking I'd use it.  Problem was when I dug it out tonight, it had more dents and bondo on it than the worst beater car on frat row would at our college.  It was also missing the petcock, just like the blue tank and a spare red one I have.  The deal breaker was that it was kind of crusty inside and I just don't want to mess with problems like that now.  So I grabbed an extra '77 tank I had that was perfect inside, had a petcock on it, and isn't a real gem on the outside.  Race bikes aren't supposed to be perfect!!

Tomorrow I'm going to try to do the small battery/one wire/toggle switch race electrical system and a carb swap so this thing will come to life.  I can't wait to hear this baby fire up!





If anybody knows what kind of pipe that is please let me know.  I think a long time ago I decided it was a Jardine, but I don't remember how I came to that conclusion.

Craig