Did more research on these engines, it is a 31cc Weedie engine, very similiar to a RYOBI. However, the cylinder hold down bolts (2) set at an angle, unlike the Ryobi that set at a right angle to the crankshaft. The venturi on the carb is about the same as the Ryobi. The crankshaft is very similiar to a Robi long shaft, but the rod journal is larger. The wrist pin is the same size as the Ryobi. It has a single wide ring. Thanks for any info. FLATHEAD