The NAMURA NA-50005K Top End Kit is a complete standard-bore replacement kit designed for select Polaris 500 sport ATV applications. This kit includes a piston, piston rings, wrist pin, wrist-pin clips, top-end bearing, and gasket kit for a comprehensive upper-engine refresh. It is engineered for compatibility with 2006–2007 Polaris Outlaw 500 models and 2003–2007 Polaris Predator 500 models, helping simplify installation and restore dependable top-end performance.
The piston uses NAMURA’s MOS2, or Teflon/molybdenum, coated skirts. This rolled-on coating process creates a strong bond while helping reduce friction, improve heat transfer, and minimize the risk of cold seizures during operation. The machined smooth head reflects combustion heat and helps limit carbon buildup, supporting piston protection and efficient engine performance. An anodized dome adds heat resistance and durability, while the hypereutectic casting process provides increased silicon content for controlled expansion, improved wear resistance, and reliable operation at elevated cylinder temperatures.
With an 11:1 compression ratio and standard-bore design, the NAMURA NA-50005K is intended for a direct top-end service application when the cylinder remains within standard specifications. Always verify cylinder condition, piston clearance, compression requirements, and model-specific service information before installation. The kit is identified by manufacturer part number NA-50005K and vendor part number 186-5005.
Features:
- Complete top-end kit includes piston, rings, wrist pin, clips, top-end bearing, and gasket kit
- Standard-bore piston with an 11:1 compression ratio for compatible Polaris 500 ATV applications
- MOS2 Teflon/molybdenum coated skirts help reduce friction, improve heat transfer, and minimize cold-seizure risk
- Machined smooth piston head helps reflect combustion heat and reduce carbon buildup
- Anodized dome improves heat resistance and piston durability
- Hypereutectic casting process provides controlled expansion, added wear resistance, and improved high-temperature performance
- Fitment: 2006–2007 Polaris Outlaw 500 and 2003–2007 Polaris Predator 500
- Brand: NAMURA; Manufacturer part number: NA-50005K; Vendor part number: 186-5005
Fitment:
2003 Polaris Predator 500
2004 Polaris Predator 500
2005 Polaris Predator 500
2006 Polaris Outlaw 500
2006 Polaris Predator 500
2007 Polaris Outlaw 500
2007 Polaris Predator 500