Beefed Up Final Drive Gear Set For GY6 Engines With 2.555 To 1 Ratio 18T 46T Upgrade For 139QMB 139QMA 147QMD Scooters Mopeds Go Karts 49cc 50cc 80cc 100cc Performance Transmission Upgrade

GY6 Scooters 2.555:1 Final Drive Gear Set Upgrade
✔️ 2.555:1 final drive ratio; fits 139QMB/139QMA/147QMD

This upgrade is a complete final drive gear set designed for GY6-based engines used in scooters, mopeds, go-karts, and ATVs. It replaces the stock gears to boost top speed and provide a more usable RPM range when paired with a big bore kit or performance transmission.

✅ 2.555:1 final drive ratio for higher top speed and improved cruising RPM
✅ Replaces stock final drive gear and front counter shaft
✅ Fits most Chinese 139QMB/139QMA/147QMD engines in scooters, mopeds, go-karts
✅ Requires pressing gears off the shaft and counting teeth before install (18T/46T variants)

💡 What is a final drive gear set for gy6 engines and why upgrade it?

Handy overview for riders considering gearing upgrades:

• Enhanced 2.555:1 final drive ratio improves top speed while keeping rpm in a usable range
• Works well with big bore kits and performance transmissions for a steady ride
• Fits common gy6 families like 139QMB, 139QMA, and 147QMD

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