Universal Parts 47mm 72cc Big Bore Cylinder Kit - 139QMB

Give your compatible 139QMB scooter a bigger-displacement foundation for your next off-road build. This Universal Parts 47mm cylinder kit upgrades a matching 50cc four-stroke engine to 72cc and brings together the cylinder, piston, rings and installation gaskets in one convenient kit.

This product is intended for off-road use only. This product is not intended for use on public roads or land.

Key Features

• 72cc upgrade: Increase displacement on compatible 139QMB-based 50cc four-stroke engines.
• Matched top-end components: Includes the cylinder, piston, rings, piston pin and circlips.
• Included gaskets: Head and base gaskets are supplied for the top-end installation.
• Finned cylinder: External cooling fins suit the air-cooled engine layout.
• Defined fit-check dimensions: A 47mm bore, 52.7mm sleeve outer diameter and 13mm wrist pin help you plan your build.

Technical Specifications

• Brand: Universal Parts
• Part number: 151-255
• Engine application: Compatible 139QMB-based four-stroke engines
• Upgrade displacement: 72cc
• Cylinder bore: 47mm
• Cylinder sleeve outer diameter: 52.7mm
• Wrist pin diameter: 13mm
• Total piston height: 34.4mm
• Compression height: 17.25mm, measured from the wrist-pin hole center to the top edge of the piston
• Kit contents: Cylinder, piston, rings, piston pin, circlips, head gasket and base gasket

Compatibility

For matching Chinese scooter 139QMB-based 50cc / 80cc engine applications using the following engine codes. This kit provides a 72cc configuration; verify existing components on previously modified engines.

Installation note: You may need to modify your engine case to accommodate the cylinder's 52.7mm sleeve outer diameter.

Check the engine code stamped on your scooter before ordering. Engines marked with a listed code may use this kit, but verify sleeve clearance, wrist-pin diameter and piston dimensions against your engine. A code containing “QM” or “FM” alone is not enough to confirm fitment.

• 47mm bore upgrades compatible 139QMB 50cc four-stroke engines to 72cc
• Includes cylinder, piston, rings, piston pin and circlips
• Includes head gasket and base gasket
• Finned air-cooled cylinder
• Engine case modification may be required for the 52.7mm sleeve

Brand: Universal Parts; Part number: 151-255; Application: compatible 139QMB-based four-stroke engines; Upgrade displacement: 72cc; Bore: 47mm; Sleeve outer diameter: 52.7mm; Wrist pin: 13mm; Total piston height: 34.4mm; Compression height: 17.25mm; Includes: cylinder, piston, rings, piston pin, circlips, head gasket, base gasket; Engine case modification may be required; Off-road use only

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