sounds like a stereotypical sieze. You ran it too hot, the engine starts to sieze, so it cuts out. Just as it's siezing it's hot enough to combust the new gasoline charge without the spark-plug firing. Backfires and quits till the piston has time to cool and shrink. Check the plug to make sure it's not all white and blistered. You might be running too lean or you might just have pushed it too much. Hope that helps.