Originally Posted by
toofless
if you had the air filter off and the gap on the slider was very little then there is an air leak check the head bolts make sure the carby is tight and tha back plate is tight how old is the motor?was it new or used ? the only way a motor can run wild is if there is an air leak or the throttle is wide open or near it
Air leak could come from the fuel tank/lines as well. Bubbles in the fuel line will lean your engine out pretty fiercely.