I never blame an engine for anything, it's always me that is at fault when an engine misbehaves. At 11.24 to 1 compression ratio my 1.50 commands respect. Of course C&H Ignition has turned it into a ***** cat. My newly rebuilt Enya .80 kicked back Wednesday and rid itself of both nuts and the prop, luckily I found it all still in the neighborhood. A backfire is an exhaust system explosion caused by an overly rich exhaust on deceleration on older carb equipped engines. Gasoline powered Farmall tractors were especially good at backfiring.