80cc (47mm) REPLACEMENT PISTON KIT

FOR QMB139 / 139QMB 4-STROKE BIG BORE ENGINES

DIRECT REPLACEMENT FOR 47mm BIG BORE CYLINDER KITS

Restore compression and engine performance with this complete 47mm replacement piston kit for QMB139 4-stroke 47mm big bore cylinder kits. Designed as a direct replacement for worn or damaged pistons, this kit includes everything needed to refresh the piston assembly during an engine rebuild or top-end service.

⭐ FEATURES

• Brand New Replacement Piston Kit
• Designed for 47mm Big Bore Cylinder Kits
• Fits QMB139 / 139QMB 4-Stroke Engines
• High-Strength Lightweight Aluminum Piston
• Precision Machined for Proper Fit
• Excellent Heat Dissipation
• Restores Compression
• Improves Engine Performance
• Ideal for Top-End Rebuilds
• OEM-Style Replacement
• Durable Cast Ring Set
• Ready for Installation

KIT INCLUDES

✔ 47mm Piston

✔ Complete Piston Ring Set

✔ 13mm Wrist Pin

✔ (2) Wrist Pin Circlips

Everything Needed to Replace Your Existing Piston Assembly

SPECIFICATIONS

Engine Type

• QMB139 / 139QMB
• Air-Cooled
• Single Cylinder
• 4-Stroke

Piston Diameter

• 47mm

Wrist Pin Diameter

• 13mm

Overall Piston Height

• 34.1mm

Material

• High-Strength Aluminum Alloy

Ring Material

• Cast Iron / Steel

Engine Displacement

• Fits 47mm Big Bore Cylinders
• Approximately 72cc (Commonly Sold as 80cc)

PERFORMANCE BENEFITS

✔ Restores Lost Compression

✔ Improves Engine Starting

✔ Better Throttle Response

✔ Smoother Engine Operation

✔ Reduced Blow-By

✔ Improved Oil Control

✔ Excellent Replacement for Worn Pistons

✔ Precision Fit for Long Service Life

✔ Works with Stock Connecting Rod

FITMENT

Designed for 47mm Big Bore QMB139 / 139QMB Cylinder Kits

Fits many Chinese scooters including:

• TaoTao
• Ice Bear
• Wolf Brand Scooters
• Jonway
• JMStar
• Roketa
• SUNL
• Tank
• Peace Sports
• Gator
• BMS
• Baja
• Dongfang
• Znen
• Redcat
• Kazuma
• NST
• Puma
• Eagle
• Lifan (QMB139 Models)
• Many Other Chinese Scooters Equipped with QMB139 Engines

IMPORTANT FITMENT INFORMATION

⚠ This piston is designed ONLY for 47mm Big Bore Cylinder Kits.

It will NOT fit:

• Stock 39mm 50cc Cylinders
• 44mm 60cc Cylinder Kits
• 50mm Big Bore Kits
• GY6 125cc Engines
• GY6 150cc Engines
• Minarelli 2-Stroke Engines
• Honda Ruckus
• Honda Metropolitan

Always measure your existing piston before purchasing.

Compare:

• Piston Diameter
• Wrist Pin Diameter
• Overall Piston Height
• Ring Groove Design

Please review all photos and specifications before ordering.

INSTALLATION NOTES

• Verify piston ring end gap before installation.
• Install piston with the directional arrow facing the exhaust port.
• Lubricate piston, rings, wrist pin, and cylinder with clean engine oil during assembly.
• Install circlips securely in their grooves.
• Stagger ring end gaps according to manufacturer recommendations.
• Always use new gaskets when rebuilding the top end.
• Break in the engine properly after installation.

BREAK-IN RECOMMENDATIONS

For maximum engine life:

• Vary engine RPM during the first 100 miles.
• Avoid sustained full throttle during break-in.
• Change engine oil after the first 100–150 miles.
• Recheck valve adjustment after the initial break-in period.

WHY REPLACE YOUR PISTON?

Over time, pistons and piston rings wear from heat, friction, and normal engine operation. Replacing the piston assembly can help:

• Restore engine compression
• Improve power and acceleration
• Reduce oil consumption
• Improve fuel efficiency
• Reduce piston slap and engine noise
• Extend overall engine life

QUALITY PARTS • FAST SHIPPING • EXPERT SUPPORT

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