Product Description
This 40mm bore top-end rebuild kit is designed as an aftermarket replacement for many 50cc two-stroke mini dirt bike engines.
It includes a cylinder head, cylinder barrel, piston assembly, rings, pin, circlips, and gaskets—providing all essential components to restore compression and improve overall engine performance.
The kit follows a PW50-style 40mm top-end configuration, making it suitable for engines that use similar layout and dimensions.
Features
• Complete top-end rebuild kit with cylinder, piston, rings, and gaskets
• Aftermarket replacement for 40mm-bore 50cc two-stroke engines
• High-quality aluminium alloy construction with precision machining
• Standard 40mm piston size for reliable compression
• Ideal for restoring worn, seized, or low-power engines
• PW50-style design for engines using similar top-end dimensions
Specifications
Piston
• Diameter: approx. 40 mm
• Height: approx. 50.21 mm
Piston Pin
• Length: approx. 33.08 mm
• Diameter: approx. 9.99 mm
Compatibility
Suitable for many 50cc two-stroke mini dirt bikes and small recreational engines that use a 40mm PW50-style top-end layout.
Fitment varies between engine manufacturers—please confirm dimensions with your existing components before purchasing.
This is an aftermarket replacement component, not an OEM part.
Package Includes
• 1 × Cylinder head
• 1 × Cylinder barrel (40mm bore)
• 1 × 40mm piston
• 2 × Piston rings
• 1 × Piston pin
• 2 × Circlips
• 1 × Base gasket
• 1 × Head gasket
Shipping
Shipped from Melbourne, Australia.
Next-business-day dispatch for stocked items.
