Greetings All, my son just got a bike. The engine is a two stroke, identical to the two strokes that Im seeing on the pics here and other sites. I'm want to determine the engine size so that I can get replacement piston and rings, and / or cylinder if needed. All I can tell you now is the piston's diameter is about 1 13/16 " . The guy he bought it from said it's an 80 CC but I want to be sure of the size before I buy any parts. Is there any thing else I can give that would help determine the engine size. Any help would be much appreciated