Restore top-end performance with the NAMURA Top End Kit, Part Number NA-40011-2K. This 84.95 mm, +0.50 mm oversize kit features an 11:1 compression ratio and is designed for select Yamaha 450 ATV and UTV applications. The complete kit includes a piston, piston rings, wrist pin, circlips, top-end bearing, and gasket kit for a convenient engine rebuild solution.
The piston uses a hypereutectic casting process that increases silicon content to help reduce expansion and improve wear resistance under elevated cylinder temperatures. The MOS2, or Teflon/Molybdenum, coated skirts are applied using a rolled-on process that creates a stronger bond than conventional spray-on coatings. This coating helps improve heat transfer, reduce friction, and minimize the risk of cold seizures. Machined smooth heads help reflect combustion heat and reduce carbon buildup, while anodized domes provide improved heat resistance and durability.
Fitment includes 2011–2014 Yamaha YFM450FGP Grizzly 4WD EPS with IRS, 2006–2009 Yamaha YXR450F Rhino 450, and 2007–2008 Yamaha YFM450FG Grizzly 4WD with IRS. Verify the engine model, bore requirement, compression ratio, and application before installation. The manufacturer is NAMURA, and the vendor part number is NA-40011-2K.
Features:
- Complete top-end kit: Includes piston, piston rings, wrist pin, circlips, top-end bearing, and gasket kit
- Application: 84.95 mm, +0.50 mm oversize piston with an 11:1 compression ratio for select Yamaha 450 ATV and UTV engines
- MOS2-coated skirts: Rolled-on Teflon/Molybdenum coating helps improve heat transfer, reduce friction, and minimize cold-seizure risk
- Machined smooth head: Helps reflect combustion heat and reduce carbon buildup on the piston crown
- Anodized dome: Improves heat resistance and piston durability
- Hypereutectic construction: Higher silicon content helps reduce expansion and improve wear resistance at elevated cylinder temperatures
- Fitment: Fits select 2006–2009 Yamaha YXR450F Rhino 450 and 2007–2014 Yamaha YFM450FG and YFM450FGP Grizzly 450 models with IRS
Fitment:
2003 Yamaha YFM450FA Kodiak 4WD [IRS]
2004 Yamaha YFM450FA Kodiak 4WD [IRS]
2005 Yamaha YFM450FA Kodiak 4WD [IRS]
2006 Yamaha YFM450FA Kodiak 4WD [IRS]
2006 Yamaha YFM450FX Wolverine 4WD [SRA]
2006 Yamaha YXR450F Rhino 450
2007 Yamaha YFM450FG Grizzly 4WD [IRS]
2007 Yamaha YFM450FX Wolverine 4WD [SRA]
2007 Yamaha YXR450F Rhino 450
2008 Yamaha YFM450FG Grizzly 4WD [IRS]
2008 Yamaha YFM450FX Wolverine 4WD [SRA]
2008 Yamaha YXR450F Rhino 450
2009 Yamaha YFM450FG Grizzly 4WD [IRS]
2009 Yamaha YFM450FX Wolverine 4WD [SRA]
2009 Yamaha YXR450F Rhino 450
2010 Yamaha YFM450FG Grizzly 4WD [IRS]
2010 Yamaha YFM450FX Wolverine 4WD [SRA]
2011 Yamaha YFM450FG Grizzly 4WD [IRS]
2011 Yamaha YFM450FGP Grizzly 4WD EPS [IRS]
2012 Yamaha YFM450FG Grizzly 4WD [IRS]
2012 Yamaha YFM450FGP Grizzly 4WD EPS [IRS]
2013 Yamaha YFM450FG Grizzly 4WD [IRS]
2013 Yamaha YFM450FGP Grizzly 4WD EPS [IRS]
2014 Yamaha YFM450FG Grizzly 4WD [IRS]
2014 Yamaha YFM450FGP Grizzly 4WD EPS [IRS]