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Hey guys I bought a 2013 crf150rb about a month ago.  When I first got the bike it was really hard to kick over and had a ton of compression.  I had to stand it up and jump down with all my weight to get it running, my dad even had trouble kicking it but I just assumed it was normal because the guy I bought it off of told me it has a high compression piston. Well it's been a month and I prolly put about 5 hours on it and now the compression has dropped a lot to the point where I can kick it over pretty easily which I thought was the way they were support to be. It still has compression but not near what it had before. I know these bikes have compression releaser things on the cam and I was told that it had a hot cam put in it so I figured the person who performed the job messed the compression release thing up causing it to have so much compression. Could that of happened and me riding it caused it too fix itself now having less compression or did I blow something in the topend? It still starts up and runs with plenty of power that's why I don't think it's a topend problem. I'm sure hoping it was the compression release. And could somebody please give me an idea of how hard they should be to kick over? Now after it lost compression I can push it down with my arm but barely, I have to use all my strength but I can easily kick it over but u have to do it fast to start it, is that normal or should it be a pain in the ass too start like before? Thanks and sorry for such a long post!

 

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I might add, 

on a 4-stroke, performing a leakdown test gives more of an indication of the state of compression/cylinder sealing than a regular compression test.

 

Not knowing your previous 4-stroke ownership experience, 4T MX engines become hard to start when the valvetrain is out-of-adjustment or worn.

The intakes valves may have tightened up to the point they're being held off the seats / loosing compression.

Edited by mlatour

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