my 80 has been fouling out lately. i think the mix got to much gas left and it died one day tried kicking notihng. pulled the plug cleaned it kicked it. started up ran for about 2 minutes and died. tried kicking again nothing. after a few kicks it let off alot of pressure out the exhaust. fouled spark plug again cleaned made sure there was spark. did again ran for a sec and died. same thing again. any ideas also whats the gap suppose to be on the plug?