Want an easy, reliable way to turn your 150cc GY6 into a true performer? The NCY 61mm Big Bore Cylinder Kit bumps displacement to **171.3cc** — giving Genuine Buddy 150/170i scooters and GY6-based 125/150cc bikes a stronger pull everywhere in the rev range, without needing to cut or modify the engine cases. The Details NCY’s 61mm cylinder is the only drop-in big-bore kit of its size available in the U.S. (as far as we know). With a smaller outer cylinder skirt diameter of 62.99 mm — compared to the common 65 mm — it clears your engine cases with no machining required. The kit also includes a precision lightweight piston designed to reduce rotating mass, helping the engine rev quicker and improve overall ride feel. Combined with performance upgrades like a big-valve head or free-flowing exhaust, you’ll get a noticeable bump in acceleration and torque where you actually ride everyday. Specifications Designed for Genuine + GY6 125/150cc engines Outer Cylinder Skirt Diameter: 62.99 mm 54mm stud spacing Bore Size: 61mm Displacement: 171.3 cc (approx.) Piston, rings, wrist pin, and clips included Base gasket + head gasket included Does not include head assembly Compatibility Overview Compatible with Genuine scooters and most GY6-based 125/150cc engines with the following codes: 157QMJ, 161QMK, 152QMI, 1P61QMK, YN1P57QMJ, 1P52FMI, 154FMI, JJ157QMJ, 1P57QMJ, BN157QMJ, BN161QMK-A and similar QMJ / QMK / QMI engines. Important Things to Note If your engine code includes “QM” or “FM”, this kit is generally compatible. Works best when combined with a performance head and exhaust for optimal airflow. This kit upgrades the cylinder only — your stock head must be reused or upgraded. Performance parts are intended for off-road / closed-course use where applicable. Not sure about fitment? Send us your engine code and we’ll verify compatibility before you order. What's Included 61mm NCY Cylinder (171.3 cc) Lightweight piston Piston rings Wrist pin + circlips Base gasket + head gasket Ready to install onto compatible GY6/Genuine engines — no case cutting required.
