I traded for a 01 yz250f, we ride in the woods. It starts good cold and hot if it is shutdown with the stop button. If it stalls in tight spots it is hard to restart. It usually has to sit for awhile before it will restart. The valves are in spec. the bikes runs good and starts fairly easy as long as it is not stalled. I was told this was a cam problem with the earlier 250f's that yamaha had changed the cams on the later ones.