Restore top-end performance with the Namura NA-50015-4K Top End Kit. Designed with a 39.98 mm +1.00 mm piston and an 11:1 compression ratio, this kit includes the essential components needed for a reliable piston replacement, including the piston, rings, wrist pin, wrist-pin clips, top-end bearing, and gasket kit. The kit is engineered for proper fitment and dependable service in compatible Polaris Outlaw 50 applications.
The Namura piston uses a hypereutectic casting process that increases silicon content to help control expansion, improve wear resistance, and withstand elevated cylinder temperatures. Its MOS2, or Teflon/molybdenum, coated skirts use a rolled-on application process that creates a bond reported to be significantly stronger than spray-on coatings. This coating helps reduce friction, improve heat transfer, and minimize the risk of cold seizures during operation.
Additional piston design features support durability and combustion efficiency. The machined smooth head helps reflect combustion heat and reduce carbon buildup, while the anodized dome improves heat resistance and strength compared with non-anodized piston designs. These features help protect the piston in demanding riding conditions and support consistent engine performance.
This Namura top-end kit fits 2008 through 2017 Polaris Outlaw 50 models. Verify the model year, piston specification, and required oversize before installation. Manufacturer part number: NA-50015-4K. Vendor part number: 186-50154.
Features:
- Complete top-end kit: Includes piston, rings, wrist pin, wrist-pin clips, top-end bearing, and gasket kit
- 39.98 mm +1.00 mm piston: Provides the specified oversize configuration for compatible Polaris Outlaw 50 applications
- 11:1 compression ratio: Designed for the specified engine configuration
- MOS2-coated skirts: Rolled-on Teflon/molybdenum coating helps reduce friction, improve heat transfer, and minimize cold-seizure risk
- Machined smooth head: Helps reflect combustion heat and reduce carbon buildup on the piston
- Anodized dome: Improves heat resistance and durability compared with non-anodized piston designs
- Hypereutectic casting: Increased silicon content helps control expansion, resist wear, and withstand higher cylinder temperatures
- Fitment: Fits 2008-2017 Polaris Outlaw 50 models
Fitment:
2007 Polaris Predator 50
2008 Polaris Outlaw 50
2009 Polaris Outlaw 50
2010 Polaris Outlaw 50
2011 Polaris Outlaw 50
2012 Polaris Outlaw 50
2013 Polaris Outlaw 50
2014 Polaris Outlaw 50
2015 Polaris Outlaw 50
2016 Polaris Outlaw 50
2017 Polaris Outlaw 50
2018 Polaris Outlaw 50