A9 Camshaft GY6 50cc (139QMB) - High-Lift Performance

A9 High-Lift Camshaft for GY6 50cc Engines

The A9 High-Lift Performance Camshaft is made for GY6 50cc (139QMB) scooters. It is built to raise engine output, especially at higher RPMs. Among GY6 50cc scooter parts, it targets mid-range power and top speed. It suits riders moving to big bore kits from 72cc up to 100cc, as its design supports better airflow and efficiency.

High-Lift Profile for Greater Power Output

This camshaft uses a strongly aggressive lift profile, rising above stock specifications, which makes it a popular pick among performance-minded riders. Pre-installed low-friction bearings help the shaft turn smoothly, and the hardened steel alloy body resists wear over long use. Together these traits support dependable running under demanding conditions.

Fitting and Compatibility

The A9 camshaft drops in as a replacement for the factory 139QMB camshaft and, in standard installations, does not require any machining of the cylinder head. It works with a broad range of 4-stroke 50cc Chinese scooters, giving riders many options for an engine upgrade.

Specifications

• Material: Hardened steel alloy
• Intake Lobe: 26.50mm (±0.05mm)
• Exhaust Lobe: 26.35mm (±0.05mm)
• Bearings: Pre-installed 16002/P6 rated ball bearings
• Certification: ISO 9001
• Includes: Complete camshaft with pre-installed bearings
• Fits: GY6 50cc 4-stroke engines with 139QMA or 139QMB heads, incl. 1P39QMB, YN139QMB, BN139QMB, 147QMD

Fitment

Compatible with:

• GY6 50cc 4-stroke engines with 139QMA or 139QMB heads (most Chinese 50cc scooters)
• 139QMA, 139QMB, 1P39QMB, 1P39QMA-2
• YN139QMB, JJ1P39QMB, 139FMA-2, BD1P39QMB
• BN139QMB, 147QMD
• Other QMA and QMB variants

How to choose: Compare the engine code cast into your engine (for example, 139QMB) with the codes above. Codes containing "QM" or "FM" are the most likely match.

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