Naraku 47mm Performance Piston Kit – QMB139 – #NK100.63

Naraku 47mm Performance Piston Kit is a high-quality replacement piston designed for QMB139 50cc/49cc 4-stroke engines equipped with a 47mm big bore cylinder. This kit restores lost compression and ensures smooth engine operation — ideal for rebuilds, repairs, or routine maintenance on your performance setup.

When paired with a stock 41.4mm stroke crankshaft, this piston provides a total displacement of 72.8cc, delivering a noticeable increase in power and throttle response while maintaining everyday reliability.

Features:

• Genuine Naraku performance replacement piston kit

• Designed for 47mm big bore cylinders (72cc conversion)

• Precision-machined aluminum piston for durability and heat dissipation

• Restores compression and maintains OEM-level reliability

• Ideal for rebuilds and performance upgrades

Specifications:

• Bore Size: 47mm

• Wrist Pin Diameter: 13mm

• Piston Height: Approx. 36mm

• Compression Height: 20mm (center of wrist pin to piston crown)

• Works with stock 41.4mm stroke crankshaft (72.8cc total displacement)

• Compatible with QMB139/GY6 50cc 4-stroke engines

Includes:

• Piston

• Piston Rings

• Wrist Pin

• Circlips (x2)

Compatibility:

• QMB139 50cc / 49cc 4-stroke engines

• GY6-based scooters