The Namura NA-50003-4K Top End Kit is designed for select Polaris 300 two-stroke applications requiring a 75.47 mm piston with a +1.00 mm oversize fit. This comprehensive kit includes the piston, piston rings, wrist pin, wrist-pin clips, top-end bearing, and gasket kit for a convenient top-end rebuild. It fits the 1996–1999 Polaris Xpress 300 and 1996–1999 Polaris Xplorer 300 4X4.
Performance-focused construction helps support reliable operation in demanding powersports applications. The piston uses a hypereutectic casting process with increased silicon content to help reduce expansion, improve wear resistance, and withstand higher cylinder temperatures. The MOS2 Teflon/molybdenum-coated skirts are applied through a rolled-on process that creates a strong bond while helping reduce friction, improve heat transfer, and minimize the risk of cold seizures.
The machined smooth head is designed to reflect combustion heat and help reduce carbon buildup, protecting the piston crown during operation. An anodized dome improves heat resistance and durability, while the included rings, wrist pin, clips, bearing, and gasket components provide the essential parts needed for installation. Verify the cylinder bore, oversize requirement, engine configuration, and model year before ordering to ensure proper fitment.
Features:
- Complete Top End Kit: Includes piston, rings, wrist pin, wrist-pin clips, top-end bearing, and gasket kit
- MOS2-Coated Skirts: Rolled-on Teflon/molybdenum coating helps strengthen the bond, reduce friction, improve heat transfer, and help prevent cold seizures
- Machined Smooth Head: Reflects combustion heat and helps reduce carbon buildup to protect the piston
- Anodized Dome: Improves heat resistance and durability compared with non-anodized piston domes
- Hypereutectic Construction: Increased silicon content helps reduce expansion, improve wear resistance, and withstand higher cylinder temperatures
- Fitment: Fits 1996–1999 Polaris Xpress 300 and 1996–1999 Polaris Xplorer 300 4X4 models
- Size: 75.47 mm piston with +1.00 mm oversize specification
- Brand: Namura
- Manufacturer Part Number: NA-50003-4K
- Vendor Part Number: 186-50034
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