ok, i have a yamaha xt125, 1982... it will kick over but will not stay running. it has spark, compression, i cleaned the whole carb out 3 times with carb cleaner and a wire brush... the lights work and horn and everyhting else, but when i kick start it, it will just die out or backfire... i had it running before for about 1 minute and hit the throttle and killed it... i have no clue whats wrong with it. please help! i also just put a new spark plug in..