1981 CM 400C Tracker Build

callmesb

It's a jungle man...gotta swing.
Okay, I'm overdue to start this. I've been bombing a bunch of other folks' threads with questions, so maybe I can generate some dialogue in my own thread.

Here's where the bike stood when I bought it in 1995. It remained like this until I started cutting in April of last year. This isn't my photo, but the bike looked exactly the same, excellent condition and all.

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I first removed the side covers, removed the seat, removed the front and rear fenders, removed the chain guard, took out the air box, and removed the carbs for cleaning. After that I swapped in some DCC Mx bars for the goofy stock bars.

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Next I sawed and ground off the rear of the stamped frame behind the suspension, and got rid of the bugle exhaust. Picture below is an original mock up using a single seat and a raw steel fender. I've since decided (tentatively) to try and use a KZ900 rear cowl for the tail/fender, and will custom fab a seat from the original seat pan.

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Here's where the bike stood as of last week. I removed the headlight and gauges since the last shot, relocated the ignition to beneath the tank, removed the electronics bracket and moved some of the wiring, and ground off unnecessary welds/brackets on the frame (like the rear foot peg brackets).

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This week, I received a few shipments of items to help square away the front end. A new speedo, fork gaiters, headlight brackets (courtesy of DCC). Fork seals (courtesy of Bike Bandit). Pipe wrap, high-temp silicone coating spray, and steel zip ties (through Amazon). And a tach-drive plug (courtesy of DTT member CrazyPJ).

I have some work to do today, starting with the fork seals, then the wiring (ugh).

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Last week, I got my carb back from a buddy who had it over the winter to clean it up. It was dumping gas and also bogging down during acceleration at the end of last season. So, I removed it and gave it to my friend for service.

Well, I kinda dropped the ball on ordering the needed replacement gaskets last fall, so it sat at my buddies...in pieces. When I finally got back in touch, the carb tubes had been lost, so another set was ordered. I owe him a case of beer for dealing with my indecisiveness.

The carb looked like this when I started last week. It took me a while to get it back together using my Clymer's manual, but I think it's done properly. I still have to put gas in it and give it the official test.

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Here is some inspiration I've been using. Not a lot of CM400s that I've seen handled gracefully in the style I like, so my reference is mostly from other bike styles.

A nice rear-end solution to my same basic frame shape (from the DTT thread http://www.dotheton.com/forum/index.php?topic=31377.20 ):

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A CM build that was using a KZ900 tailpiece, as I'd like to do (from DTT thread http://www.dotheton.com/forum/index.php?topic=9699.0 ) This build has evolved away from this solution since this photo was taken.

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Great use of a KZ900 tail and Supertrapp on a Motohangar build. Great stance. I'd be using riser bars, instead of clip-ons, though.

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A look close to what I'd like to achieve (BMW engine aside):

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A Classified Moto build that has a nice tank, tail and seat solution to a Virago dipped cruiser frame:

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Here's a nice frame mod to a CM400 that I am considering:

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Swivel said:
"high-temp silicone coating spray",.....What's this stuff.and what's it for?

It says for sealing and protecting exhaust wraps.


Swivel said:
You should linish your fork tubes to get the seal to work right and also they will then look like brand new.....
PM me if you want to know how to linish them right....

I am going to rebuild the forks today. I have a Clymer's with instructions, but maybe that isn't the best approach? The tubes and sliders are both in really nice condition and will clean up nicely with just a cotton cloth, so outside of the rebuild, I wasn't going put much time into them.


Swivel said:
You should read all the threads on this site about Firestone tires before shelling out all the bucks.....

I've heard the whispers about the Firestones. I'm okay with a better set of tires, but I'd really like to find that perfect balance between performance and style, and I'd like to avoid "sport bike" tires. I'm always appreciative of suggestions.


Swivel said:
You need to gently stretch the rubber diaprams on the carb slides up to the daylight and check for pinhole sized holes.A pinhole size hole will upset how it runs.....Refit the airbox if you ever want it to run right and fast again.Honda CV carbs without the OEM airbox frustrate the best pro tuners.....Forget the beer can pod restriction nonsense...

I'm I ----- I this close to ditching the shitty Keihin carbs for a set of Mikuni VM30s. They clog every year, and are miserable to adjust. Also, the air box is long gone, so pod filters and Mac 2-1 (or custom 2-1 with a collector) exhaust is probably in the near future.


Swivel said:
Comstar wheels look great when painted VHT gloss black spraycan epoxy.....

I have a set of front and rear CB750 hubs that I plan to lace up to 18" rear and 19" front rims. Wanna buy a pair of Comstars? ;) Referring back to my question from the thread I bombed, since other CMs of the same frame type and year-range came with factory 18" rear and 19" front, is it a wildly bad idea to put the same on my CM 400C? I'd probably swap in new rear shocks, but change the height to keep the swing arm angle from changing drastically.
 
Personally it sounds like you've got a pretty good idea of what you want to build and ride. I say go for it. As for the carbs With the right amount of time and effort put forth, there is no reason they shouldn't work.
 
Some progress to report... I rebuilt the forks and got them back on.

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I added gaiters and some athletic tape to the tops to add some visual heft.

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I also installed a new speedo and headlight brackets courtesy of DCC.

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I purchased a tailpiece from a KZ900 and tried out a few different mockups. I'm leaning towards the middle position.

Forward
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Middle
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Rearward
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Some new progress. I finally brought in some help, and also invested in some long-overdue parts. I'll post as it progresses. For now, here's the stripped frame which will be having a new tail welded on, and some new spoked rims, freshly sandblasted and painted.
 

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With the scrambler theme in your build and that dip in your frame it immediately made me think of some classic scramblers seats...
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Even ducati was thinking it ;)..
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Might save you a lot of fabrication on a sub frame.

Psy

Sent from my SM-G903W using Tapatalk
 
Or like this...
 

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Awesome build! My cb400 had the same headlight bucket, and I was far happier after upgrading to something closer to the scrambler aesthetic:

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Another trick is mounting that same bucket upside down:

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Sent from my iPhone using DO THE TON
 
Some progress...got new wheels and shoes on her, got the new tank situated and mocked it up and then welded a new tail on. Next will come the battery box and electronics.
 

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