• 47mm Performance Big Bore Cylinder Kit (80cc Upgrade) for GY6 50cc 139QMB 4-Stroke Scooter ATV - goofitmoto
  • 47mm Performance Big Bore Cylinder Kit (80cc Upgrade) for GY6 50cc 139QMB 4-Stroke Scooter ATV - goofitmoto
  • 47mm Performance Big Bore Cylinder Kit (80cc Upgrade) for GY6 50cc 139QMB 4-Stroke Scooter ATV - goofitmoto
  • 47mm Performance Big Bore Cylinder Kit (80cc Upgrade) for GY6 50cc 139QMB 4-Stroke Scooter ATV - goofitmoto
  • 47mm Performance Big Bore Cylinder Kit (80cc Upgrade) for GY6 50cc 139QMB 4-Stroke Scooter ATV - goofitmoto
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GOOFIT

47mm Performance Big Bore Cylinder Kit (80cc Upgrade) for GY6 50cc 139QMB 4-Stroke Scooter ATV

47mm Performance Big Bore Cylinder Kit (80cc Upgrade) for GY6 50cc 139QMB 4-Stroke Scooter ATV

$37.99
$37.99
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Product Overview

Unlock hidden power in your GY6 engine with the GOOFIT 47mm Big Bore Cylinder Kit. Designed to upgrade standard 49cc/50cc units to 80cc, this kit is the perfect balance of performance and reliability. Crafted from high-strength aluminum alloy with a wear-resistant coating, it provides an immediate boost in torque and acceleration without the need for complex engine modifications.

Product Compatibility

A universal top-end upgrade for 4-stroke GY6 horizontal engines.

Engine Platform Upgrade Potential Fitment Type
GY6 49cc / 50cc Upgrades to 80cc Standard 139QMB / 139QMA
GY6 60cc / 80cc Direct Replacement Maintenance & Repair
Compatible Vehicles ATVs, Scooters, Mopeds, Karts TaoTao, Peace Sports, Wolf, Ice Bear

Specifications

Attribute Details
Cylinder Inner Diameter 47mm / 1.85"
Piston Pin Outer Diameter 13mm / 0.51"
Engine Type 4-Stroke GY6 (139QMB)
Material High-Strength Aluminum Alloy
Coating Premium Wear-Resistant Hardened Layer

Key Features

  • Instant Performance Upgrade: Efficiently increases your displacement to 80cc, providing the extra power needed for hills, passengers, and higher cruising speeds.
  • Thermal-Stable Construction: Made of premium aluminum alloy that dissipates heat faster than stock cast iron, ensuring stable performance during long-distance rides.
  • Wear-Resistant Hardened Bore: The inner cylinder wall features a specialized coating that reduces friction and extends the life of the piston rings and cylinder.
  • Quick & Simple Installation: Engineered as a "Bolt-On" solution, this kit requires no machining or complex modifications to your original crankcase.
  • Comprehensive Accessory Pack: Includes everything for a professional seal: cylinders, pistons, rings, valve seals, and a full set of gaskets, bolts, and exhaust nuts.
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Fitment FAQ

Will this part fit my specific model and year?

This cylinder piston kit is intended for A universal top-end upgrade for 4-stroke GY6 horizontal engines .; Engine Platform; Upgrade Potential; Fitment Type; GY6 49cc / 50cc; Upgrades to 80cc; Standard 139QMB / 139QMA. Key physical/spec details from the product data include Cylinder Inner Diameter: 47mm / 1.85", Piston Pin Outer Diameter: 13mm / 0.51", 47mm. Use the compatibility table and product photos together before ordering.

Do I need to match the OEM part number?

Yes. If your original part has a stamped OEM or manufacturer number, match that number first before ordering. For this cylinder piston kit, also compare the bore diameter, piston-pin size, gasket pattern, stud spacing, engine code, stroke type, and cylinder height. This is especially important for GY6 GY6 models because similar model names can use different parts by year or trim.

What models or situations does this part not fit?

Do not order this cylinder piston kit for machines outside the listed compatibility, or for units with different bore sizes, piston-pin diameters, stroke lengths, stud spacing, or gasket patterns. Do not rely only on the model name or engine size.

What should I check before ordering?

Before ordering, compare your original part with the photos and check the bore diameter, piston-pin size, gasket pattern, stud spacing, engine code, stroke type, and cylinder height. Recheck listed specs such as Cylinder Inner Diameter: 47mm / 1.85", Piston Pin Outer Diameter: 13mm / 0.51", 47mm. If any connector, mounting point, size, or year detail is different, confirm fitment before installation.