Please note that I also posted this same question in the XR80-200 forum. My neighbor bought a used 2001 XR200. We recently replaced the piston and rings and reinstalled everything. However, once we got the valve cover and all other parts back in place, the bike would not kick over. We removed the valve cover and double checked to ensure that we were on TDC and put everything back together again. Still no luck...it seems when we tighten the cap bolts down on the valve cover, it locks up the cam. We also referred to the manual and the cam is installed with the lobes facing down, as it appears to be in the manual. Any thoughts on why this might be happening? Is it possible that the cam chain is too tight/loose? Is it possible that the cap bolts are too tight? We are planning on pulling the motor out and taking everything apart again to check everything, but I figured I would check here first to see if anyone has any insight. Thanks in advance for any assistance!