Glixal GY6 100cc Big Bore Cylinder Kit 50mm for 139QMB/139QMA — Complete Piston, Rings & Gaskets

The Glixal GY6 100cc 50mm Big Bore Cylinder Kit is a complete high-performance replacement cylinder kit designed to upgrade compatible 139QMB/139QMA GY6 engines from 49–50cc to a 100cc 50mm bore.

This kit supplies everything needed to rebuild or big-bore a GY6-style 139QMB/139QMA 4-stroke engine commonly found on many Chinese scooters and small ATVs. Components are sized and packaged for a straightforward swap: the kit includes the 50mm cylinder, piston with rings, piston pin and clips, gaskets, valve oil seals, studs and exhaust hardware. Before purchasing, verify your engine model to ensure fitment with GY6 139QMB series engines.

Will this cylinder kit fit my scooter or ATV?

Compatibility is limited to GY6 139QMB and 139QMA 4-stroke engines; it fits many Chinese scooter and ATV models but not all GY6 variants. Confirm your engine code or consult your vehicle manual to match the 139QMB/139QMA designation. Using this kit on non-compatible engines can cause fitment problems.

• Designed specifically for GY6 139QMB/139QMA engines
• Commonly compatible with JONWAY, JMSTAR, ROKETA, SUNL, TANK, PEACE, TAOTAO
• Not for unrelated engine types—verify model before buying

How does the 50mm big bore improve performance?

Increasing bore size to 50mm raises displacement to approximately 100cc, which typically delivers stronger mid-range torque and higher potential top speed compared with standard 49–50cc configurations. Performance gains depend on carburetion, exhaust, and final gearing—additional tuning is often required to realize the full effect.

• 50mm inner cylinder diameter for larger displacement
• Piston and rings matched to the bore for proper sealing
• Recommended to tune carburetor and exhaust after installation

What parts are included and what should I inspect before installation?

The kit arrives with a full set of parts needed for a rebuild or upgrade, so you won’t need separate hardware for a standard swap. Before starting the job, inspect all gaskets, studs, and the piston for shipping damage, and check that the cylinder seat and head surface are clean and flat for reliable sealing.

• Includes cylinder, piston, rings, piston pin and clips
• Contains gaskets, valve oil seals, tensioner and exhaust gaskets
• Comes with intake/exhaust studs and exhaust nut for assembly

Is special machining or tools required to install this kit?

Most installations are standard engine-rebuild procedures and do not require custom machining if the engine case is in good condition. Basic mechanical tools and torque specifications for the GY6 platform are sufficient; however, check bore and crankcase alignment and replace any worn bearings or seals discovered during disassembly.

• Standard hand tools and torque wrench recommended
• Inspect and replace bearings or seals as needed
• No custom machining expected for correct 139QMB/139QMA fit

Who is this for: Riders and mechanics who want a reliable, plug-and-play big-bore upgrade for GY6 139QMB/139QMA 4-stroke scooters and small ATVs. It’s intended for users comfortable with engine rebuilds or professional installers seeking a complete replacement kit that consolidates all necessary components to increase displacement and refresh worn cylinder components.