NCY 88cc Big Bore Kit (52mm) - 139QMB / GY6 50

NCY 52mm 88cc Big Bore Kit - Extreme Power for QMB139 Engines

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.

Performance Highlights

• Maximum Displacement: Increases your engine to a true 88cc for superior hill climbing and acceleration.
• Cast Iron Durability: Provides excellent longevity and reliability for daily commuting.
• Precision Honing: Optimized cylinder walls for reduced friction and improved ring seating.
• Professional Grade: The preferred choice for "screamer" builds across the scooter racing community.

Detailed Model Fitment

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.

Recommended Support Mods

• Big Valve Head: Use with the NCY 50mm Big Valve Head for optimal flow.
• Crankcase Pressure: Install an NCY Decompression Tube to manage increased engine pressure.
• Jetting: Carburetor re-jetting is required (Typically #85-#95 Main Jet depending on altitude).

*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

This product is not intended for use on public roads or land.

Agility 50, Like 50, Super 8 50, People 50 (4T). ATM50-A1, Pony 50, Thunder, VIP Future Champion. Cali Classic 50, Havana 50, PCH 50, SYM Fiddle II 50. Maddog 50 (Gen I-V), Wolf RX-50, Wolf Lucky, Islander.