TB 160cc Bore Kit with New large valve (23.5/30mm) Race Head and Mikuni VM 26mm Carb kit. For 124/140/146cc engines with a 57mm stroke (GPX, Jailing type engines). Must have 13mm Piston pin. Includes an all aluminum ceramic coated skirtless cylinder, piston kit, head gasket kit, and a 28mm carb kit. No case boring required.