There is water in the gas pumps at our local gas pumps. A Lot of people with snow blowers have Jerry cans full of gas stored inside their sheds usually in the warm. The water is still mixed with gas & goes directly into the blower tank. If you left the Jerry can outside the water will freeze & sink to the bottom.
He has taken apart the carb on these engines & seen ice in the bowl. This will cause the engine to buck & spit & it tore up the piston head. I would double check the plug, valve, & the carb for broken or missing parts. If your cylinder wall is OK how could it be a piece of ring ?? I hope your problem isn't too serious as I have the same engine....
A doubtful ol' trucker
