Ive got an 09 CRF250r that is not running right. I can get it started on the choke and by kicking it and doing all sorts of things with the throttle. Ive fought this for the last 6 months as im trying to get it ready to sell, and I want to sell it honestly running. It has spark. New OEM spark plug. Valves are in spec, and have never zeroed a valve. Timing is on. Repeat, timing is on. I have put a carb off of a running CRF and put it on it, and doesn't make a difference. I pulled the top end off and inspected it. No scarring on cylinder, and head tests out good. I tried compression testing it with a kit, but the kit is hard to tighten down in the spark plug port because of the long neck going to the spark plug. I got a reading of 30psi, but I believe I couldn't get a good seal on it. When I put it back together after inspecting the top end, I made sure rings were set right, and I poured some oil down on the piston as the manual states. The bike started up ok for a few seconds, but then would not run off choke, and eventually would not run on choke as it warmed up. Just wondering if I am fighting low compression due to a piston/ rings problem? Any help would be appreciated.