The Namura NA-50091-CK Top End Kit is designed for select Polaris 900 twin-cylinder engines, including the RZR 900, RZR 900 S, RZR 900 Trail, and Ranger XP 900. This complete kit includes the piston, piston rings, wrist pin, wrist pin clips, top-end bearing, and gasket kit for a comprehensive upper-engine rebuild. The kit features a 92.97 mm piston with a +0.02 oversize configuration and is engineered for reliable fitment and durable performance.
Namura uses a hypereutectic casting process to provide increased silicon content, controlled expansion, improved wear resistance, and the ability to withstand elevated cylinder temperatures. The piston skirts feature a MOS2 coating made from Teflon and molybdenum. 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 piston head helps reflect combustion heat and reduce carbon buildup, supporting piston protection and consistent engine performance. An anodized dome further improves heat resistance and durability, making this top-end component well suited for demanding recreational, utility, and off-road applications. The Namura NA-50091-CK kit is a practical replacement solution for restoring compression and refreshing the top end of compatible Polaris engines.
Fitment: 2015-2016 Polaris RZR 900; 2015-2016 Polaris RZR 900 S; 2016 Polaris RZR 900 Trail; 2013-2017 Polaris Ranger XP 900. Verify the vehicle model, year, engine configuration, and required oversize before installation.
Features:
- Complete top-end kit includes piston, rings, wrist pin, clips, top-end bearing, and gasket kit
- 92.97 mm piston with +0.02 oversize configuration for compatible Polaris 900 twin-cylinder engines
- MOS2 Teflon and molybdenum-coated skirts help reduce friction, improve heat transfer, and limit 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, enhanced wear resistance, and improved high-temperature capability
- Fits select 2013-2017 Polaris RZR 900 and Ranger XP 900 models
Fitment:
2013 Polaris Ranger XP 900
2014 Polaris Ranger XP 900
2015 Polaris Ranger XP 900
2015 Polaris RZR 900
2015 Polaris RZR 900 S
2016 Polaris Ranger XP 900
2016 Polaris RZR 900
2016 Polaris RZR 900 S
2016 Polaris RZR 900 Trail
2017 Polaris Ranger Crew XP 1000
2017 Polaris Ranger Crew XP 900
2017 Polaris Ranger XP 900
2017 Polaris RZR 900
2017 Polaris RZR 900 S
2018 Polaris Ranger Crew XP 900
2018 Polaris Ranger XP 900
2018 Polaris RZR 1000 RS1
2018 Polaris RZR 900
2018 Polaris RZR 900 S