The Namura NA-40004-6 piston kit is designed for select Yamaha 660 powersports applications, including the YFM660FG Grizzly 4WD with independent rear suspension and the YXR660F Rhino 660. This oversize piston measures 101.47 mm and is intended for engines prepared for a 1.50 mm oversize piston. With a 9.2:1 compression ratio, it is engineered to provide a reliable replacement solution for applicable rebuilt or bored cylinders.
This Namura piston kit is compatible with 2002–2008 Yamaha YFM660FG Grizzly 4WD models with IRS and 2004–2006 Yamaha YXR660F Rhino 660 models. Confirm the cylinder bore, piston clearance, compression requirements, and application details before installation. The piston must be matched with the appropriate components for the prepared cylinder and installed according to the manufacturer’s service procedures.
Important: The Namura NA-40004-6 piston kit will not accept OEM rings, and the included or compatible rings will not work with an OEM piston. Do not combine this piston with original-equipment rings or use OEM pistons with rings intended for this kit. Manufacturer part number: NA-40004-6. Vendor part number: 187-400046.
Features:
- Size: 101.47 mm oversize piston for a 1.50 mm overbore application
- Model: Yamaha YFM660FG Grizzly 4WD with IRS and Yamaha YXR660F Rhino 660
- Compression Ratio: 9.2:1
- Brand: Namura
- Manufacturer Part Number: NA-40004-6
- Vendor Part Number: 187-400046
- Fitment: 2002–2008 Yamaha YFM660FG Grizzly 4WD with IRS and 2004–2006 Yamaha YXR660F Rhino 660
- Compatibility: Does not accept OEM piston rings, and the supplied or compatible rings will not work with an OEM piston
Fitment:
2001 Yamaha YFM660R Raptor
2002 Yamaha YFM660FG Grizzly 4WD [IRS]
2002 Yamaha YFM660R Raptor
2003 Yamaha YFM660FG Grizzly 4WD [IRS]
2003 Yamaha YFM660R Raptor
2004 Yamaha YFM660FG Grizzly 4WD [IRS]
2004 Yamaha YFM660R Raptor
2004 Yamaha YXR660F Rhino 660
2005 Yamaha YFM660FG Grizzly 4WD [IRS]
2005 Yamaha YFM660R Raptor
2005 Yamaha YXR660F Rhino 660
2006 Yamaha YFM660FG Grizzly 4WD [IRS]
2006 Yamaha YXR660F Rhino 660
2007 Yamaha YFM660FG Grizzly 4WD [IRS]
2007 Yamaha YXR660F Rhino 660
2008 Yamaha YFM660FG Grizzly 4WD [IRS]