Complete 72cc Iron cylinder & Head kit!!!This works with most Chinese 50cc 4-stroke 139QMB engines. Pump up that weak engine to a respectable 72cc displacement, on a budget. This kit is not indended to make your scoot a screaming race-machine. It is intended to get you that extra power you need to keep pace and stay safe on the roads.Most chinese 50cc’s only put down around 1.5hp to the ground (hardly enough to safely transport yourself without ending up like Frogger).Increase the reliability & power of your scoot today!! NOTE: Remove your valve from your scooter’s head and meaure the full length of the valve stem. Some scooters like Znen(Wolf Brand, GMW, Bintelli, etc), Kymco 50cc 4T(Agility), some newer TaoTao and other 50cc 4-stroke scooters may have valve stem length over 64mm. For these applications use part #1100-1326 Type 1 Rocker Arm assembly.