Jul 9, 2007
Alright my buddy with an 02 CR 125 just came back from an wrist injury, got on his bike and did a few laps around his track and he says that after a few laps there was pretty much zero top end power, he thought he blew the top end.

Well he took it up here where we did some checking on it. The obvious stuff like bad spark plug, carb problems, clogged airfilter were all checked. Those looked all relitively good execpt for a slightly gunked up pilot jet which shouldnt effect top end power.

Then we checked some more advanced stuff. We pulled the pipe off and checked out the exhaust (RC) valve. Other then some shot gaskets and grommet, nothing. The valve moved fine. The Piston and ring looked in tact from looking in threw the exhaust port and there was no splatter or any kind of debris in the cylinder that would indicate a hole in the piston. We dont have a compression guage yet, Im looking around for a decent one, but it sure feels like its got decent compression when it kicks over.

The next guess was the reeds, they are fine also! So now Im thinking ignition? Any thoughts on this problem? Personally I didnt get to ride it to check it out, I wish I did but he insisted that we didnt ride it because he figured it had major engine issues and it would cause big $$ damage if we did! So now Ive got a half dissasembled CR 125 in the garage.


Apr 28, 2006
i think it is your ignition, does your friend wash it with a high pressure hose, i'v seen ignition wires ripped off from a pressure washer, just check around, pull ur gas tank and check it out
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