Oct 29, 2007

I'm a new member here with a problem. I scored a CR125 off a mate about a year ago and burn't a hole in the top of the piston cuz of my fuel mix... (Too Rich) Anyway, 400$ later... New Piston/Ring,... I get the bitch to start. Took her for a ride and notice that I wasnt getting the best power out of it, and felt different to ride. Definately feels compression related, I can't kick-start it either. I only noticed today that iv'e been running it with the choke twisted out by about 2mm's. That wouldnt cause my bike to choke down while im riding it? Or could it be the explanation for this?

Ever since I fixed her back up, She's been leakin oil out the top. It's as tight as **** but.

Is there a seal in the bottom of the engine within the cases that has something to do with compression?

Would running my bike with the choke on cause all the oil to leak from the end of the exhaust and thru the topend of the bike's engine?

Thanks heaps for the help guys. Catch. :ride:


Jan 14, 2007
Too rich of a mixture wouldn't cause put a hole in the top of the piston. What spark plug was in it at the time. You could have an air leak some where causing a lean condition.


Aug 24, 2007
If your riding around with the choke on it'll definitely make it run like crap. It'll be sputtering and bogging, should also foul a plug relatively soon.

Oil coming out he top? I don't what that means. :coocoo:


Jun 22, 2007
You have to make sure it's the proper torque on the cylinder... if it's too tight it can blow the gasket (causing leakage). Like hot125mod said running too rich won't cause it to burn a hole in the top of the piston... I'd check jetting, air leaks etc. And the choke... haha yeah that wouldn't help.

PS - Did you break in the new top end? And yes, there is crank seals... those could cause you some trouble.
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