Hello, hopefully someone here can help. I have a 2009 kfx50. I ran fine and then one day I just would not start. nothing not even with starting fluid. I noticed the oil was very low and thought the rings went bad. I took it apart and everything looked fine so I put a new set or rings on. still no good. I did a compression test and it had 100 psi on the 3 rd or 4th stroke. I then got a new whole top end even valves. replaced everything and still only get 100 psi. if I put a little oil in the cylinder it goes up to about 150 psi but then goes back to 100. I thought we might have messed up the timing so I was playing with the cam but nothing changed. I was surprised when I took the cam right out so the valves would not open and my compression only went up to 25psi I would have thought I could get the maximum if there was no way for the air to get out of the cylinder. when I was setting everything back up I had the flywheel set to the T and I had the cam set at TDC so there was just a little play in the rocker. I kept trying it with the tensioner cap off thinking it should not matter since the only way for air to escape is from the plug or the valves. can someone help. I have spent to much money on this thing already. I should add that it has great spark and the carb works.