The Namura NA-40005-4 piston kit is designed for select Yamaha Grizzly 350 ATV applications and features an 83.95 mm piston size with a +1.00 mm oversize specification. This replacement piston kit supports engine rebuilding and cylinder service when the original cylinder requires boring to accommodate the oversize piston.
Fitment: Fits 2007–2014 Yamaha YFM350FG Grizzly 4WD with SRA, and 2007–2008 Yamaha YFM350G Grizzly 2WD with SRA. Confirm the year, model, cylinder bore requirements, and service specifications before installation.
This Namura piston kit is manufactured for compatible Yamaha Grizzly 350 engines and is identified by manufacturer part number NA-40005-4 and vendor part number 187-400054. The kit is intended for applications requiring the specified +1.00 mm piston size. Proper cylinder measurement, machining, piston-to-cylinder clearance, and assembly procedures are essential for reliable engine operation.
Important: This piston kit will not accept OEM piston rings, and the included or corresponding rings are not compatible with an OEM piston. Use the correct Namura ring set for this piston and follow the applicable Yamaha and Namura installation instructions.
Features:
- Brand: Namura
- Manufacturer Part Number: NA-40005-4
- Vendor Part Number: 187-400054
- Piston Size: 83.95 mm
- Oversize: +1.00 mm
- Application: Yamaha Grizzly 350 ATV engine rebuilds
- Fitment: 2007–2014 Yamaha YFM350FG Grizzly 4WD with SRA
- Fitment: 2007–2008 Yamaha YFM350G Grizzly 2WD with SRA
- Compatibility: Will not accept OEM piston rings, and the rings will not work with an OEM piston
Fitment:
1987 Yamaha Bw350
1987 Yamaha YFM200DX Moto-4
1987 Yamaha YFM225 Moto-4
1987 Yamaha YFM350ER Moto-4
1987 Yamaha YFM350FW Big Bear 4WD [SRA]
1987 Yamaha YFM350X Warrior
1988 Yamaha Bw350
1988 Yamaha YFM200DX Moto-4
1988 Yamaha YFM225 Moto-4
1988 Yamaha YFM350ER Moto-4
1988 Yamaha YFM350FW Big Bear 4WD [SRA]
1988 Yamaha YFM350X Warrior
1989 Yamaha YFM200DX Moto-4
1989 Yamaha YFM250 Moto-4
1989 Yamaha YFM350ER Moto-4
1989 Yamaha YFM350FW Big Bear 4WD [SRA]
1989 Yamaha YFM350X Warrior
1990 Yamaha YFM250 Moto-4
1990 Yamaha YFM350ER Moto-4
1990 Yamaha YFM350FW Big Bear 4WD [SRA]
1990 Yamaha YFM350X Warrior
1991 Yamaha YFM250 Moto-4
1991 Yamaha YFM350ER Moto-4
1991 Yamaha YFM350FW Big Bear 4WD [SRA]
1991 Yamaha YFM350X Warrior
1992 Yamaha YFM350ER Moto-4
1992 Yamaha YFM350FW Big Bear 4WD [SRA]
1992 Yamaha YFM350X Warrior
1993 Yamaha YFM350ER Moto-4
1993 Yamaha YFM350FW Big Bear 4WD [SRA]
1993 Yamaha YFM350X Warrior
1994 Yamaha YFM350ER Moto-4
1994 Yamaha YFM350FW Big Bear 4WD [SRA]
1994 Yamaha YFM350X Warrior
1995 Yamaha YFM350ER Moto-4
1995 Yamaha YFM350FW Big Bear 4WD [SRA]
1995 Yamaha YFM350FX Wolverine 4WD [SRA]
1995 Yamaha YFM350X Warrior
1996 Yamaha YFM350FW Big Bear 4WD [SRA]
1996 Yamaha YFM350FX Wolverine 4WD [SRA]
1996 Yamaha YFM350U Big Bear 2WD [SRA]
1996 Yamaha YFM350X Warrior
1997 Yamaha YFM350FW Big Bear 4WD [SRA]
1997 Yamaha YFM350FX Wolverine 4WD [SRA]
1997 Yamaha YFM350U Big Bear 2WD [SRA]
1997 Yamaha YFM350X Warrior
1998 Yamaha YFM350FW Big Bear 4WD [SRA]
1998 Yamaha YFM350FX Wolverine 4WD [SRA]
1998 Yamaha YFM350U Big Bear 2WD [SRA]
1998 Yamaha YFM350X Warrior
1999 Yamaha YFM350FX Wolverine 4WD [SRA]
1999 Yamaha YFM350X Warrior
2000 Yamaha YFM350FX Wolverine 4WD [SRA]
2000 Yamaha YFM350X Warrior
2001 Yamaha YFM350FX Wolverine 4WD [SRA]
2001 Yamaha YFM350X Warrior
2002 Yamaha YFM350FX Wolverine 4WD [SRA]
2002 Yamaha YFM350X Warrior
2003 Yamaha YFM350FX Wolverine 4WD [SRA]
2003 Yamaha YFM350X Warrior
2004 Yamaha YFM350FA Bruin 4WD [SRA]
2004 Yamaha YFM350FX Wolverine 4WD [SRA]
2004 Yamaha YFM350R Raptor
2004 Yamaha YFM350X Warrior
2005 Yamaha YFM350FA Bruin 4WD [SRA]
2005 Yamaha YFM350FX Wolverine 4WD [SRA]
2005 Yamaha YFM350R Raptor
2006 Yamaha YFM350FA Bruin 4WD [SRA]
2006 Yamaha YFM350R Raptor
2007 Yamaha YFM350FG Grizzly 4WD [SRA]
2007 Yamaha YFM350FGI Grizzly 4WD [IRS]
2007 Yamaha YFM350G Grizzly 2WD [SRA]
2007 Yamaha YFM350R Raptor
2008 Yamaha YFM350FG Grizzly 4WD [SRA]
2008 Yamaha YFM350FGI Grizzly 4WD [IRS]
2008 Yamaha YFM350G Grizzly 2WD [SRA]
2008 Yamaha YFM350R Raptor
2009 Yamaha YFM350FG Grizzly 4WD [SRA]
2009 Yamaha YFM350FGI Grizzly 4WD [IRS]
2009 Yamaha YFM350G Grizzly 2WD [SRA]
2009 Yamaha YFM350R Raptor
2010 Yamaha YFM350FG Grizzly 4WD [SRA]
2010 Yamaha YFM350FGI Grizzly 4WD [IRS]
2010 Yamaha YFM350G Grizzly 2WD [SRA]
2010 Yamaha YFM350R Raptor
2011 Yamaha YFM350FG Grizzly 4WD [SRA]
2011 Yamaha YFM350FGI Grizzly 4WD [IRS]
2011 Yamaha YFM350G Grizzly 2WD [SRA]
2011 Yamaha YFM350R Raptor
2012 Yamaha YFM350FG Grizzly 4WD [SRA]
2012 Yamaha YFM350FGI Grizzly 4WD [IRS]
2012 Yamaha YFM350G Grizzly 2WD [SRA]
2012 Yamaha YFM350R Raptor
2013 Yamaha YFM350FG Grizzly 4WD [SRA]
2013 Yamaha YFM350R Raptor
2014 Yamaha YFM350FG Grizzly 4WD [SRA]