Ok well i was riding my 1996 ktm 250 sx and it stalled after riding it for a little bit. When i went to kick it over it was locked up, and i thought great cyclinder is junk or the crank is seized but neither. After a while it started to move again. I figured i rip the motor down to see what was wrong, and the cylinder is perfect, piston looks fine, and the crank moves freely. the bike had plenty oil and coolant. When i pulled one of the powervalve covers off i saw that one of the screws had come out. Dont see how this would make it lock up seeing as it was running with the screw out? Motor has new a new crank bearing and the other side was fine minimal wear. The crank was recently out and checked, also minimal wear. Not sure what the problem is here.