This ATV motorcycle starter overrunning clutch is compatible with Max 500, 650, 800, 800R, and 1000R EFI LTD STD 4X4 and 6X6 engines.Compatible models include: HD8 (2017–2021) HD10 (2017–2021) Rro T HD10 (2017–2021) Max HD10 (2017–2021) 6X6 HD10 DPS (2021) DPS (2021) 500 (2008–2009) 500 EFI (2010) 500 EFI STD (2012–2013) 800 (2008) 800 X (2008) 800R EFI (2011) 800R EFI X (2009) 800R EFI STD (2009–2010) 800R EFI Xxc (2010–2011) 1000R EFI (2015) 500 4X4 (2007) 500 STD 4X4 (2007) 500 (2008) 500 STD (2008) 500 EFI (2009–2013) 650 4X4 (2006–2007) 650 (2008) 650 STD (2008) 650 STD 4X4 (2006–2007) 650 EFI (2009–2011) 650 EFI 6X6 (2015) 650 EFI (2009–2012) 800 STD 4X4 (2006–2007) 800 (2008) 800 STD (2008) 800 4X4 (2006–2008) 800R EFI (2009) 800R EFI (2009–2011) 1000 EFI (2013–2015) 1000 EFI 6X6 (2015) Max 500 STD 4X4 (2007–2008) Max 500 4X4 (2007) Max 500 (2008) Max 500 EFI (2009) Max 500 EFI (2009–2013) Max 650 (2006/2008) Max 650 STD (2008/2010) Max 650 4X4 (2006–2007) Max 650 STD 4X4 (2006–2007) Max 650 EFI (2009–2012, 2016–2017) Max 650 EFI (2009) Max 800 LTD (2008/2012) Max 800 STD (2008) Max 800 STD 4X4 (2006) Max 800 (2008) Max 800 4X4 (2006) Max 800R EFI (2009–2011) Max 800R EFI (2009) Max 800R EFI Ltd (2009–2011) Max 1000 EFI LTD (2013–2015) 800 (2011/2014–2017) 1000 (2011) LTD 1000 (2012–2015) Max 1000 (2014–2015) MAX Turbo (2021) Max 1000 (2013–2016) Trail 800R EFI (2018–2021) Trail 1000 EFI (2018–2019) Trail 1000R EFI (2018–2019) Sport Max 1000R (2019–2020) Function: Prevents reverse resistance damage to the motor.During engine startup, the starter motor drives the overrunning clutch to rotate, generating sufficient force to turn the crankshaft and initiate piston movement.Package includes: 1 x Motorcycle One Way Bearing Starter.This product is a direct replacement for parts and does not include installation instructions.