GY6 NCY Performance Cylinder Head - QMJ157

Want your GY6 to breathe better? The NCY Big Valve Cylinder Head increases airflow with larger valves — unlocking stronger throttle response and more efficient power. It’s a clean, bolt-on upgrade for common GY6-based 150cc engines and Genuine scooters that use a compatible motor.

The Details

A big-valve head allows the engine to move more air in and out of the combustion chamber — helping boost torque and top-end breathing. This NCY cylinder head uses quality valves and ports that complement popular performance upgrades like big-bore kits and exhaust systems. The result is a motor that runs smoother and responds quicker when you crack the throttle.

Perfect for riders looking to step up performance without jumping into a full race build. NCY has a long history of proven, Taiwan-made quality — so you know you’re getting a part built to last.

Specifications

• Intake valve size: 27.5 mm
• Exhaust valve size: 23.5 mm
• Designed for GY6/Genuine 150cc engines

Compatibility Overview

Compatible with engines using the following codes:

157QMJ, 161QMK, 152QMI, 1P61QMK, YN1P57QMJ, 1P52FMI, 154FMI, JJ157QMJ, 1P57QMJ, BN157QMJ, BN161QMK-A and similar QMJ / QMK / QMI motors.

Important Things to Note

• If your engine code includes “QM” or “FM”, this head is generally compatible.
• Performance heads work best with upgraded cylinders and exhaust — stock components can limit gains.
• Variations in Genuine scooters mean you should always verify your specific engine code before ordering.
• Performance parts are intended for off-road / closed course use where applicable.

Not sure about fitment? Send us your engine code — we’ll confirm compatibility before you buy.

What's Included

• NCY Big Valve Cylinder Head Assembly
• Pre-installed valves and springs
• Ready for installation onto compatible GY6/Genuine engines

You’ll reuse your existing camshaft or upgrade to a performance cam to take full advantage of the airflow gains.