YBR125 motorcycle cylinder assembly, cylinder diameter 54MM, size parameters and YBR125 engine completely match, directly replace the original cylinder, no processing crankcase interface; Including cylinder block, piston, piston ring, piston pin, one-time complete cylinder core components, save the trouble of decentralized procurement; The inner wall of the cylinder is honed, and the piston and cylinder wall are matched with precise clearance. With high-quality piston ring, the cylinder seal and compression ratio are guaranteed, and the power output is strong. The cylinder body is made of aluminum alloy and integrates multiple heat dissipation fins to quickly export the heat of the combustion chamber, avoid high temperature cylinder pulling and prolong the service life. The piston is made of wear-resistant aluminum alloy, and the piston ring is chrome plated, which has strong abrasion resistance and carbon deposition resistance, and is suitable for long-term high-load cycling.