Namura NA-50090-BK Top End Kit for Polaris RZR XP 900, 92.96 mm, 10.6:1 Compression

Restore top-end performance with the Namura NA-50090-BK Top End Kit, designed for select Polaris RZR XP 900 twin-cylinder models. This complete kit includes pistons, piston rings, wrist pins, circlips, top-end bearings, and a gasket kit for a comprehensive engine refresh. The kit is manufactured by Namura and is identified by manufacturer part number NA-50090-BK and vendor part number 186-5090B.

Built for a 92.96 mm piston size and 10.6:1 compression ratio, this top-end kit is engineered to support reliable fitment and consistent performance when servicing compatible engines. The hypereutectic casting process increases silicon content to help reduce expansion, improve wear resistance, and withstand higher cylinder temperatures. Machined smooth piston heads help reflect combustion heat, reduce carbon buildup, and protect the piston crown during operation.

Namura’s MOS2 Teflon and 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. Anodized domes further improve heat resistance and durability, providing added protection under demanding riding conditions. Before installation, verify engine specifications and compare the existing components to ensure proper application.

Fitment includes the 2011 and 2012 Polaris RZR XP 900 and the 2011 and 2012 Polaris RZR XP 900 LE. Professional installation is recommended, with all engine components inspected and clearances confirmed according to the vehicle manufacturer’s service procedures.

Features:

• Complete top-end kit includes piston, rings, wrist pin, circlips, top-end bearing, and gasket kit
• 92.96 mm piston size with a 10.6:1 compression ratio for compatible Polaris RZR XP 900 engines
• MOS2 Teflon and molybdenum-coated skirts help reduce friction, improve heat transfer, and minimize cold-seizure risk
• Machined smooth piston heads help reflect combustion heat and reduce carbon buildup
• Anodized domes provide increased heat resistance and durability
• Hypereutectic casting process delivers reduced expansion, improved wear resistance, and enhanced high-temperature performance
• Fitment: 2011 Polaris RZR XP 900, 2012 Polaris RZR XP 900, 2011 Polaris RZR XP 900 LE, and 2012 Polaris RZR XP 900 LE