C piston in B cylinder

[NM_KDX200]

I've got a brand-new C piston sitting on the shelf, but I have a B-cylinder in my '96 KDX200. How critical is the A/B/C tolerance? Think I can safely run the C?

FWIW, I actually have an A piston in the bike right now, since I ordered one before thinking to check....it's been in there a year which is why I was thinking of putting the new C in.

Thanks,

 

[jaguar]

I wouldn't do it. guys on this forum have gotten 2 years or more out of their piston so you shouldn't think of tossing your A piston just yet. Best to get a good feeler gauge and see if there is more play between piston and cylinder than is recommended (>.09mm). As long as your cylinder is in good shape then you shouldn't think of using anything other than a standard size piston. If your cylinder is thrashed then you can opt to put a steel sleeve in it or replate it or bore/replate it (to match your C piston).

 

[canyncarvr]

You need to know where you are before you know where to go.

The pro-x alpha designations are .01mm steps. That's less than 1/2 a thousandth inch! Not much to lose sleep over.

I'm running a 'B' piston in my 'C' cylinder. Ring gap and piston-to-cylinder measurements were well within spec.

A year isn't a big deal in most kdxs. As jag says, it's the measurement of the situation that will tell you what's up.

Your problems would be solved if you just sent your 'C' piston to me. Then you wouldn't have to worry about it no moh. Out of sight, out of mind!

Want my addy?
;)

 

[NM_KDX200]

>> A year isn't much....

I know, I know, but my first 2-stroke was a '76 RM-125 that I raced from '78-80 and old habits die hard. Let's see....new rings every other race, new piston every other rings, overbore every other piston....after that I rode exclusively 4-strokes until I got a '92 YZ-250 that I rode from '98-99. I could NOT believe it when I tore it down and found everything to NEW specs!!

I was just thinking more of replacing the smaller A with the bigger C (all Pro-X, by the way) for tighter clearances, not because it needs it or anything. Guess I'll just wait till this winter....

I'll spend my money on tires and chain/sprocket instead.

And finally, FWIW, I've been riding since 1975 and this KDX is the best bike I've ever had- bought it used from the 2nd owner, and I'm positive the first owner must've had the suspension worked on because it's fantastic.