Turn your 49cc/50cc scooter into a high-performance machine with the NCY 88cc Big Bore Kit. This 52mm cast iron cylinder is designed for riders who demand the maximum displacement possible from the 139QMB platform. Engineered for durability and high-heat tolerance, this kit provides a massive boost in torque and top-end speed.
This kit fits nearly all 4-stroke 50cc (QMB139 / GY6 50) scooter engines. Below are the most popular compatible models:
CRITICAL INSTALLATION NOTE: This is a 52mm kit. Most 139QMB engine cases require machining or cutting to fit the larger cylinder skirt. We highly recommend using the NCY Engine Bore Tool Order part number 1400-1001 if you do not have access to a machine shop.
*Not legal for use in California on pollution-controlled vehicles. For off-road/track use only.
NCY GY6 50/139QMB 52mm Cast Iron Cylinder Kit w/o head
