47mm Piston Rings Pin Set For 70cc 90cc Pit Bike ATV Quad This piston ring and pin set is designed for use with 47mm cylinder bores commonly found in 70cc and 90cc pit bikes, ATVs, and.The set includes piston rings and a wrist pin compatible with standard 47mm piston configurations.It supports engine rebuilds or performance by providing internal components suited for small displacement two-stroke or four-stroke engines.The parts are engineered to maintain proper compression and fit within standard tolerances for smooth.