47mm 70cc Cylinder Block Kit For RS4 RS SX SM 50cc D50B0 2-Stroke Motorcycle This cylinder block kit is designed for use with RS4 RS SX SM 50cc D50B0 2-stroke engines.It features a 47mm bore and increases engine displacement to 70cc, providing improved performance over stock configurations.The kit includes all necessary components for installation, such as the cylinder, piston, rings, wrist pin, and associated hardware.Constructed from materials, it supports under standard riding conditions.This part is intended as a direct replacement or upgrade for compatible 2-stroke motorcycle models.