WH 150cc Piston

🔧 Princess Piston (57.4mm)

📦 Part Number: MIWH150-3007

🏍️ Piston Assembly · Includes Gudgeon Pin & Circlips · For 153QMI Engines

Fits QJ153QMI Engine · Keeway ARN 125, F-act 125, Matrix 125, RY8 125, RX9 LEONE & Similar Models

This is the Princess Piston (57.4mm), part number MIWH150-3007. It is designed for the new engine type 153QMI, a modified version of the standard GY6 engine 152QMI. This piston assembly includes the piston body, gudgeon pin (piston pin), and circlips, making it an ideal choice for engine rebuilding or performance restoration.

The 153QMI engine is an optimized upgrade based on the original GY6 platform, offering improved heat dissipation and reliability. This piston is manufactured from high-quality aluminum alloy with a piston diameter of 57.0mm, paired with a 15mm precision piston pin to ensure excellent fit accuracy and wear resistance, effectively restoring engine power. This is the perfect replacement when the original piston suffers from wear, scoring, or heavy carbon buildup in the ring grooves.

Compatible Engine Model: QJ153QMI (Modified GY6 engine, upgraded version of standard GY6 152QMI)

Compatible Vehicles:

• Keeway ARN 125
• Keeway F-act 125
• Keeway Matrix 125
• Keeway RY8 125
• Keeway RX9 LEONE
• Other GY6 series vehicles equipped with QJ153QMI engines

• 153QMI Specific Design: 57.0mm piston diameter specifically designed for 153QMI modified engines, ensuring perfect fitment.
• High-Quality Aluminum Piston: Made from high-strength aluminum alloy with lightweight construction, high strength, low thermal expansion, and precise fit with cylinder walls.
• Precision-Machined Ring Grooves: Ring grooves are precision-machined to ensure smooth piston ring movement and excellent sealing performance.
• Precision Piston Pin: The piston pin is heat-treated and precision-ground with 15mm diameter and 42.5mm length for high strength and wear resistance.
• Included Circlips: Circlips are provided to securely retain the piston pin, preventing it from coming loose.
• OEM Specification Standards: Manufactured to original dimensions and parameters for perfect fitment.

🔧 Installation Guide

1. Ensure the engine is completely cooled and clean carbon deposits from the ring grooves before installation.
2. When installing the piston pin, ensure the circlips are fully seated in the circlip grooves and check they are secure.
3. When installing the piston, ensure the arrow or marking on the piston faces the exhaust side (or follow the original orientation).
4. Apply a small amount of engine oil to the piston skirt before installation to prevent dry start-up.
5. If installing with piston rings, use a piston ring compressor tool to avoid damaging the cylinder wall. Piston ring size is 1.0mm + 1.0mm + 2.0mm — rings are sold separately.
6. After installation, manually rotate the crankshaft to confirm smooth piston movement without binding.
7. It is recommended to replace piston rings simultaneously for optimal fitment.

Proper break-in is essential after installing a new piston to achieve optimal piston ring-to-cylinder wall seating:

• Break-In Period: Recommended 500-800 km (300-500 miles).
• RPM Control: Avoid prolonged high RPM operation during break-in; keep RPM below 70% of maximum.
• Load Control: Avoid hard acceleration, heavy loads, and steep hill climbing during break-in.
• Oil Change: Change oil after the first 200-300 km (120-180 miles), and again after the break-in period is complete.
• Oil Quality: Use high-quality mineral oil during break-in; switch to synthetic oil after break-in.

⚠️ Important Notice: This product is the Princess Piston (57.4mm), part number MIWH150-3007. Specifically designed for QJ153QMI engines (GY6 modified type) with 57.0mm piston diameter, 15mm piston pin diameter, and 42.5mm pin length. Fits Keeway ARN 125, F-act 125, Matrix 125, RY8 125, RX9 LEONE, and compatible models.
⚠️ Incompatibility Warning: This piston is NOT compatible with standard GY6 (152QMI) engines! Standard GY6 125cc pistons typically have a 52.4mm diameter and are not interchangeable. Please verify your engine model before purchasing.
Spec Confirmation: Before purchasing, verify your engine is the 153QMI model with a 57.0mm piston diameter.
Note: Piston rings are not included with this product. Please purchase a compatible piston ring set separately if needed (1.0mm + 1.0mm + 2.0mm). Piston installation involves critical engine components; professional installation is strongly recommended. Product images are for reference only; please refer to the actual product.