I just bought a 04 crf250x, The bike has a new crank, piston, cylinder and cam chain. The problem is that it will not start. The valves were supposedly adjusted. I have removed carb and cleaned. It will not start with button or kick start. It will start when pushed off. Runs great until it gets hot then it starts to sputter and then cuts off. I can then push start again in a few minutes. I am assuming the problem is the values but i didn't want to do valve job if not needed. checked the valves exhaust .012, intake ls .004 right side almost no gap.