2008 Crf 250 Problem

okay so i was getting alot of blowby. it wasnt leaking any oil so i guessed it was burning it. the first thing i thought i would try would be to replace the rings. so i replaced the rings, head gasket, cylinder gasket and piston clips. i put everything back together and i am hearing a weird noise. it alomst sounds like the cam chain is slapping the case. the timing is right and the valve gap is perfect. it also seems as though the cam chain is tight. the rings are also installed right. everything is torqued down properly. i have tried everything i can possibly think to try. any suggestions where to go from here?

Take out the center bolt for the timing chain tensioner so you can get to the screw inside. Take a small screwdriver and turn the screw inside there to relieve the tension. Then just pull the screwdriver out. you should here it snap and that's all you need to do to adjust it. SFire it up and see if the noise is still there. You should have replaced the piston if it has some significant hours on it, they wear also. They do use some oil so don't think that it's unusal that it's burning it.

i checked all the specs on the piston and it was fine. it was burning nearly a quart of oil a weekend.

The exhaust valve guides are prone to go bad on all of the CRF250's and 450's but a quart a weekend is a lot of oil to burn. Sounds like there's more going on. How much do you drain out of the breather over flow tube that's down by the front sprocket?

not too often.

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