Namura NA-50070K Top End Kit for 2002–2003 Polaris Sportsman 700 4x4, 79.95 mm Standard Bore

The Namura NA-50070K Top End Kit is designed for rebuilding the top end of select Polaris Sportsman 700 4x4 models with a Nikasil cylinder and 79.95 mm standard-bore piston. This complete kit includes the piston, piston rings, wrist pin, retaining clips, top-end bearing, and gasket kit, providing the essential components needed for a reliable engine refresh.

Built with Namura performance-focused materials and manufacturing processes, the piston features MOS2, or Teflon and molybdenum, coated skirts. The rolled-on coating creates a durable bond while helping reduce friction, improve heat transfer, and minimize the risk of cold seizures. The hypereutectic casting process adds silicon for controlled expansion, increased wear resistance, and improved durability under elevated cylinder temperatures.

Additional piston features include machined smooth heads to help reflect combustion heat and reduce carbon buildup, along with anodized domes that improve heat resistance and durability. These design details help protect the piston crown and support consistent performance during demanding riding conditions. The kit is intended for use with the original-equipment Nikasil cylinder configuration and standard bore.

Fitment includes the 2002 Polaris Sportsman 700 4x4 and 2003 Polaris Sportsman 700 4x4. Verify the vehicle year, model, cylinder type, and standard-bore application before installation. Manufacturer part number NA-50070K and vendor part number 186-5070 identify this Namura top-end replacement kit.

Features:

• Complete top-end kit includes piston, rings, wrist pin, retaining clips, top-end bearing, and gasket kit
• 79.95 mm standard-bore piston designed for Nikasil cylinder applications
• MOS2 Teflon and 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, increased wear resistance, and improved high-temperature performance
• Fits 2002 Polaris Sportsman 700 4x4 and 2003 Polaris Sportsman 700 4x4
• Brand: Namura; manufacturer part number: NA-50070K; vendor part number: 186-5070