Restore reliable top-end performance with the Namura NA-40008K Top End Kit. Designed for select Yamaha Kodiak and Grizzly ATV models, this 84.42 mm standard-bore kit includes the essential components needed for a complete top-end service, including a piston, piston rings, wrist pin, retaining clips, top-end bearing, and gasket kit. The 11:1 compression configuration is engineered for compatible Yamaha engines and provides a practical replacement solution for worn or damaged original components.
The Namura piston features MOS2, a Teflon and molybdenum coating applied to the skirts through a rolled-on process. This coating is designed to improve bonding strength, increase heat transfer, reduce friction, and help minimize the risk of cold seizure during operation. The machined smooth head helps reflect combustion heat and reduce carbon buildup, supporting piston protection and consistent engine performance.
An anodized dome increases heat resistance and durability, while the hypereutectic casting process adds silicon to help control expansion and improve wear resistance under elevated cylinder temperatures. These features make the Namura NA-40008K a dependable choice for rebuilding the top end of compatible Yamaha ATV engines. Verify the model, year, bore specification, and compression ratio before installation.
Fitment: 2007-2008 Yamaha YFM400FG Grizzly 4WD with IRS; 2000-2006 Yamaha YFM400FA Kodiak 4WD with SRA; and 2003 Yamaha YFM400A Kodiak 2WD with SRA. Manufacturer part number: NA-40008K. Vendor part number: 186-4008.
Features:
- Complete top-end kit includes piston, rings, wrist pin, retaining clips, top-end bearing, and gasket kit
- 84.42 mm standard-bore piston with an 11:1 compression configuration
- MOS2 Teflon and molybdenum coated piston 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 piston dome improves heat resistance and durability
- Hypereutectic casting process provides controlled expansion and increased wear resistance
- Fits select Yamaha YFM400 Kodiak and YFM400FG Grizzly ATV models
- Brand: Namura; manufacturer part number: NA-40008K; vendor part number: 186-4008
Fitment:
2000 Yamaha YFM400A Kodiak 2WD [SRA]
2000 Yamaha YFM400FA Kodiak 4WD [SRA]
2001 Yamaha YFM400A Kodiak 2WD [SRA]
2001 Yamaha YFM400FA Kodiak 4WD [SRA]
2002 Yamaha YFM400A Kodiak 2WD [SRA]
2002 Yamaha YFM400FA Kodiak 4WD [SRA]
2003 Yamaha YFM400A Kodiak 2WD [SRA]
2003 Yamaha YFM400FA Kodiak 4WD [SRA]
2004 Yamaha YFM400A Kodiak 2WD [SRA]
2004 Yamaha YFM400FA Kodiak 4WD [SRA]
2005 Yamaha YFM400FA Kodiak 4WD [SRA]
2006 Yamaha YFM400FA Kodiak 4WD [SRA]
2007 Yamaha YFM400FG Grizzly 4WD [IRS]
2008 Yamaha YFM400FG Grizzly 4WD [IRS]