72cc big bore kit for 4 stroke scooters

OK for racing! This is a high quality big bore kit suitable for upgrading most aircooled 50cc 4 strokes based on Honda's old design. This includes 95% of Chinese 4 stroke 50cc scooters (designated QMB139 / 139QMB, QMA etc) and others. (brands may include Baotian, Solana, Arrow, Fierce, Forza, "Factory Built", Wolfboy, Qingqi, Kinroad etc). The 50% increase in engine size gives lots more power and torque to your scooter. Increases acceleration, top speed and hill climbing ability. Kit includes: Coated alloy big bore cylinder, 47mm bore for 72cc displacement S-Cut short alloy piston for minimum weight and friction drag Fly cut piston crown, suits upgrades to high lift cams/big valves Piston pin (12mm) Circlips Quality base and head gaskets quality piston ring set We recommend use with our pod filters for even more power. See the 'air cleaner' category of this mechanical parts section. Engines limited in RPM by CDI will need to be derestricted to realise full upgrade potential. Note that because of inconsistency in manufacturing of scooters in China, small differences in your engine's dimensions may mean adjustment of base gaskets, crank case etc are necessary to fit this kit, but only in rare cases. This kit must be fitted and the carburetor tuned by a technician or skilled person. Piston seizure or burnt valves are symptoms of poor carb tuning and claims regarding these kinds of problems will not be accepted. This increases engine size and power so that your bike may not be legally registered as a moped in New Zealand.