180cc GY6 Big Bore Kit - 63mm Forged Piston
ITEM# TT-15719
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Description
180cc Big Bore Kit for GY6 125cc and 150cc Engines
This 63 mm forged piston big bore kit is built to raise the performance of supported GY6 125cc and 150cc four-stroke engines. Increasing the displacement to roughly 180cc gives you a stronger base for torque and acceleration. It belongs to our GY6 scooter parts range and can make a clear difference to how your engine performs.
Key Components
Everything needed for the upgrade comes in the box: a finned cylinder to help with cooling, a forged piston, piston rings, a wrist pin, retaining clips, and the gaskets required for fitting. The fins work to shed heat, which helps the engine hold steady performance. Together these parts should give you a clearly stronger power delivery.
Installation Requirements
Fitting this big bore kit means the crankcase must be modified, so it is more involved than a straight swap. You will need the correct tools, including an engine case boring tool, to do the job properly. Plan for the extra work needed to make room for the new cylinder and piston.
Specifications
- Engine application: Suits GY6 125cc / 150cc four-stroke engines; not intended for QMK or 169cc engines
- Bore: 63 mm
- Displacement: Roughly 180cc, varying with crankshaft stroke
- Outer sleeve diameter: 64.9 mm
- Cylinder height: 90 mm
- Wrist pin: 15 mm diameter × 48 mm length
- Cylinder-stud spacing: 54 × 54 mm center-to-center
- Fits: GY6 125cc and 150cc four-stroke starting engines (QMI/QMJ configurations) once the crankcase has been bored
Fitment
Fits:
- GY6 125cc and 150cc four-stroke starting engines (157QMJ, 152QMI, YN1P57QMJ, JJ157QMJ, 1P57QMJ, BN157QMJ, 1P52FMI, 154FMI and other QMI/QMJ configurations; GY6-A type)
- 54 × 54 mm cylinder-stud spacing, 15 mm wrist pin, and crankcase modification required
How to choose: Look at the engine code on the case. It needs to be a 125cc or 150cc GY6-A engine with 54 × 54 mm cylinder-stud spacing, and the case must be bored to accept the 64.9 mm sleeve.
Shop more: GY6 Scooter Parts · Chinese Scooter Parts · Scooter Big Bore & Cylinder Kits · Scooter Pistons & Piston Rings · Scooter Parts
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