Hey guys, a friend of mine has a ninja .21 that has 4 gallons on it. He just replaced the bearings, put a new rod in it and sealed it up again yet it seems to have an air leak somewhere and we cant figure out were its coming from. The motor will just ramndomly die for no aparent reason. He is running stock head shimming, O.S. P3 glow plug with 30% Sidewinder and it comes of the track at around 280 or so. Can anyone shed some light on the probable cause of our frustration. Thanks