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I've got my 89 kdx 200 I recently acquired up and running and was able to track down from the guy I bought it off of the guy he bought it off of and it seems just before the guy I got it from bought it it was rebuilt with a 0.020 wiseco piston and replated some mild port work annd the head was milled bt he didn't remember how much good news!so when I got this thing home I originally did a compression test and as it sat got 155psi,I then squirted a little amsoil down the plug hole since it had been sitting the guy said and it went to 185psi.I then used a borescope to look inside and it looked brand new with a quarter sized spot of carbon on the piston.well I've been tuning and riding the piss outta this bike and did another compression test tonight while cold again with the same snap on gauge as I used before and got 200psi.that's without a squirt of oil or anything in the cylinder which seems a little high to me when the books call for like 118-185psi.the only thing I can see to explain the jump would be the rings setting fully?I can't see the milling not showing up on the test before unless the motor was so fresh the rings hadn't seated yet correct?I did a plug chop and its spot on with the jetting and I ended up using a CGL jet needle 2nd to bottom clip with the 45/158 and the bike hauls ass and is a beast for 200cc's.on the trails and river this thing will stay with and even embarass my bros rm 250 (the few times its been out) unless you go for a straight line run the he's a few bikes ahead.

the only thing I can see to explain the jump would be the rings setting fully?

Yes. +1 more time on the flog your motor to break it in method. Follow kawi's instructions in the manual, you'll get their 185max

Isn't the motor supposed to be at operating temp when taking a compression test?

no...not really.....it will only vary just a few psi. ......example...176 cold...178 warm.

also....budget.....you need to hold the throttle wide open also....i dont know if you done that?

kdxmaniac wrote:no...not really.....it will only vary just a few psi. ......example...176 cold...178 warm.

also....budget.....you need to hold the throttle wide open also....i dont know if you done that?

absolutely!and I've never heard of it mattering on it being warmed up.

fuzzy wrote:

the only thing I can see to explain the jump would be the rings setting fully?

Yes. +1 more time on the flog your motor to break it in method. Follow kawi's instructions in the manual, you'll get their 185max

I am in no way condoning or advocating the break in metho you're describing.I did what I always do for a beak in and that's to very the throttle never pinning it and just run through its rpms and gears gradually varying the rpms constantly.

:[/quote]I am in no way condoning or advocating the break in metho you're describing.I did what I always do for a beak in and that's to very the throttle never pinning it and just run through its rpms and gears gradually varying the rpms constantly.[/quote]


your doing the breakin the right way.......i think fuzzywuzzy is refering to the wrong method just to say what will happen to your rings.....or at least i hope!

There is so much evidence that your rings set better when you ride it like you stole to break it in that to say this is wrong is... well wrong!

ok.....im going to clear something up again>> if you take a fresh engine, and just take it and dog it.....NOT GOOD! you can get to much heat in the rings and take the tension out of them. not to mention, you dont have oil soaked into the cylinder yet..........anyway, you do it however you want.

And we do. Once the bike is warmed up... all bets are off.

good for you! you make me proud.