KDXRIDER.NET

What are the tell tell signs for a worn top end?
Loss of compression and power?
My bike is fine, I’m just wondering if I should pull the RB trigger yet or should wait until it is really necessary to do the top end.
I have less than 1500 miles on the stock engine (200) on the 05 model.
I read somwhere that you needed to replace the stock piston after a year or so (I know it is strongly recommended on the 220). What about the 200?

Thanks
Wilf

Signs of a worn top end: Low compression, piston slap (rattle). There can be a lot of other things besides a worn top-end that could cause loss of power. You can always pull the jug and measure ring end-gap. You don't want to replace prematurely and waste money but you don't want the piston to hand-grenade either.

From my experience with other bikes, the factory recommended piston replacement intervals are for bikes that get raced hard every weekend.

Piston slap? Ha! You haven't much of a chance hearing such a thing on a KDX!! (that's a joke, son).

Be careful with compression readings. About the only way they mean anything is when they are compared to earlier tests on the same engine, using the same equipment and done by the same person (meaning, hopefully, done the same way).

Get compression readings on the same engine from four different people with their own testers and I guarantee you won't get the same readings.

Yeah...a compression reading of 50psi is a pretty good indication of SOME problem.

Although mileage doesn't tell the whole story, I doubt that 1500 miles is time for a rebuild.

At $150 or so, no reason to do it unnecessarily.

The 200 does not have the piston failure problems the 220 has (and has had for years).

Spend your money on your carby!! Heck, spend next year's rebuild, too..and get a DF3!!

...and NEXT year's on a shock revalve/rebuild.

..and the year after THAT for a set of KX forks! (wheel to follow).

You're up to...uh...about 2010?

Merry Christmas!!