Air leak: The rubber piece that holds my carb on, could it have been too loose? Or a case leak you mean? I haven't done a leak down test yet, trouble time finding some one with one. Fuel problem: Okay I was screwing around with the jets today so this is a strong possibility. And this did not happen during idle or low throttle, this occurred at near full throttle. I was going up in jet sizes. See I haven't wrapped my head around what happened or how it could even occur. But from what Ive read online so far my understanding is (the motor was in a lean condition and this made the plug so hot it was firing on its own?) So if the motor was lean, but I was going up in jet sizes... Thinking out-loud: Main jet was sucking too much fuel which made it lean? Float/Bowl fuel level incorrect? Thats all I got!..