I have an 08 rmz250 that I bought recently. The guy said it stopped running and smoked real bad before it stopped. I replaced the head and transferred the three good valves into it and replaced the bad exhaust valve. I lapped them all and put new valve seals and hot cams. I had the clynder professionally honed and the same man got a pro x piston specifically for the new bore size. All new gaskets. The bike runs great but smokes bad after it warms up and is going through oil pretty quick. I don't see any oil in the intake port but there is obviously some in the exhaust port but not on the valve stems. This is the second cylinder I've had on it and second piston. I've torn the motor down three times now. The oil screens were covered in nasty dirt but I thought I tore the cases down an cleaned everything well. I'm lost.