NAMURA NA-50003K Standard Bore Top End Kit for Polaris 300 Two-Stroke Models
NAMURA NA-50003K Standard Bore Top End Kit for Polaris 300 Two-Stroke Models
NAMURA NA-50003K Standard Bore Top End Kit for Polaris 300 Two-Stroke Models
NAMURA NA-50003K Standard Bore Top End Kit for Polaris 300 Two-Stroke Models

NAMURA NA-50003K Standard Bore Top End Kit for Polaris 300 Two-Stroke Models

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The NAMURA NA-50003K Standard Bore Top End Kit is designed to restore top-end performance and provide dependable service for select Polaris 300 two-stroke applications. This kit includes a piston, piston rings, wrist pin, wrist-pin clips, top-end bearing, and gasket kit for a complete upper-engine rebuild. The standard-bore piston measures approximately 2.93 inches and is engineered for a precise fit in compatible cylinders.

Features: MOS2 (Teflon/Molybdenum) coated skirts use a rolled-on application process that creates a durable bond while helping reduce friction, improve heat transfer, and minimize the risk of cold seizures. Machined smooth heads help reflect combustion heat and reduce carbon buildup, supporting piston protection and efficient engine operation. Anodized domes improve heat resistance and durability, while the hypereutectic casting process provides increased silicon content for controlled expansion, enhanced wear resistance, and improved performance at elevated cylinder temperatures.

This NAMURA top-end kit fits 1996–1999 Polaris Xpress 300 models and 1996–1999 Polaris Xplorer 300 4X4 models. Verify the vehicle year, model, cylinder condition, and required bore specification before installation. The manufacturer part number is NA-50003K, and the vendor part number is 186-5003.

Features:

  • Complete top-end kit includes piston, rings, wrist pin, clips, top-end bearing, and gasket kit
  • Standard-bore piston with an approximate 2.93-inch diameter for compatible Polaris 300 two-stroke 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 piston dome increases heat resistance and durability
  • Hypereutectic casting process provides controlled expansion and enhanced wear resistance
  • Fits 1996–1999 Polaris Xpress 300 and 1996–1999 Polaris Xplorer 300 4X4 models
  • Brand: NAMURA; manufacturer part number: NA-50003K; vendor part number: 186-5003

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