Look guys this engine doesn't go on a full scale airplane.....something did indeed go through the engine..a chunk from inside the engine like a chunk of glow plug or part of the bearings...perhaps something like a pebble of sand...if the engine isn't under warranty...and you were making power before you tore it down..clean it re install it and fly it..make sure the piston goes back in the sleve the same way it came out...in other words don't turn the piston around......once you stop making power or dead stick alot I'd replace the engine..after all...piston, piston sleve, and both bearings is a rebuild...whats left? case and crankshaft...IMHO might as well buy new for 150 bucks