The NCY Big Valve Cylinder Head allows the cylinder in your Genuine or GY6 scooter engine breathe better! Specifications: Intake valve size: 27.5 Exhaust valve size: 23.5 Fits Genuine 150cc or GY6 scooter engines Compatibility: This part is compatible with engines with the following engine codes: 157QMJ 161QMK 152QMI 1P61QMK YN1P57QMJ 1P52FMI 154FMI JJ157QMJ 1P57QMJ BN157QMJ BN161QMK-A Other QMJ, QMK, and QMI models Don't see your engine listed? If the engine code includes "QM" or "FM" this part is compatible with your vehicle. Additional Recommendations: We suggest the following add-ons to complete your NCY cylinder head purchase: NCY 61mm cylinder assembly NCY Racing Valves for GY6 engines NCY 8mm Exhaust Pipe Studs NCY Exhaust Pipe Nuts Made in Taiwan.