The NAMURA NA-50003-6K Top End Kit is designed for select Polaris 300 two-stroke applications and provides the essential components needed for a dependable top-end rebuild. This kit includes a piston, piston rings, wrist pin, wrist-pin clips, top-end bearing, and gasket kit for convenient installation and service.
The piston features MOS2, or Teflon/molybdenum, coated skirts applied through a rolled-on process. This coating creates a strong bond while helping improve heat transfer, reduce friction, and minimize the risk of cold seizures. Machined smooth heads help reflect combustion heat and reduce carbon buildup, supporting piston protection and consistent engine performance. The anodized dome improves heat resistance and durability, while the hypereutectic casting process increases silicon content for controlled expansion, enhanced wear resistance, and improved performance under elevated cylinder temperatures.
This NAMURA top-end kit is sized at 75.97 mm with a +1.50 mm overbore specification and is intended for compatible replacement-cylinder applications. It fits 1996–1999 Polaris Xpress 300 models and 1996–1999 Polaris Xplorer 300 4X4 models. Verify the existing cylinder bore, piston clearance, and engine configuration before installation to ensure proper fitment and reliable operation.
Features:
- Complete top-end kit includes piston, rings, wrist pin, wrist-pin clips, top-end bearing, and gasket kit
- 75.97 mm piston size with a +1.50 mm overbore specification
- MOS2 Teflon/molybdenum coated skirts help reduce friction, improve heat transfer, and minimize cold-seizure risk
- Machined smooth piston heads help reflect combustion heat and reduce carbon buildup
- Anodized piston domes provide increased heat resistance and durability
- Hypereutectic casting process supports controlled expansion and improved wear resistance
- Fits 1996–1999 Polaris Xpress 300 and 1996–1999 Polaris Xplorer 300 4X4 two-stroke models
- Brand: NAMURA
- Manufacturer part number: NA-50003-6K
- Vendor part number: 186-50036
Fitment:
1996 Polaris Xplorer 300 4X4
1996 Polaris Xpress 300
1997 Polaris Xplorer 300 4X4
1997 Polaris Xpress 300
1998 Polaris Xplorer 300 4X4
1998 Polaris Xpress 300
1999 Polaris Xplorer 300 4X4
1999 Polaris Xpress 300