Harley-Davidson FLSTF Fat Boy K&N Air Intake System - RK-3909-1

Harley-Davidson
2012 - FLSTF Fat Boy
2012 - FLSTFB Fat Boy Lo
2012 - FLSTN Softail Deluxe/Heritage/Nostalgia
2011 - FLSTC Heritage Softail Classic
2011 - FLSTF Fat Boy
2011 - FLSTFB Fat Boy Lo
2011 - FLSTN Softail Deluxe/Heritage/Nostalgia
2011 - FLSTSB Cross Bones
2011 - FXCWC Rocker C
2011 - FLTRX Road Glide Custom
2010 - FLSTC Heritage Softail Classic
2010 - FLSTF Fat Boy
2010 - FLSTFB Fat Boy Lo
2010 - FLSTN Softail Deluxe/Heritage/Nostalgia
2010 - FLSTSB Cross Bones
2010 - FXCWC Rocker C
2010 - FXSTC Softail Custom
2010 - FLTRX Road Glide Custom
2009 - FLSTC Heritage Softail Classic
2009 - FLSTF Fat Boy
2009 - FLSTN Softail Deluxe/Heritage/Nostalgia
2009 - FLSTSB Cross Bones
2009 - FXCW Rocker
2009 - FXCWC Rocker C
2009 - FXSTB Softail Night Train
2009 - FXSTC Softail Custom
2008 - FLSTC Heritage Softail Classic
2008 - FLSTF Fat Boy
2008 - FLSTN Softail Deluxe/Heritage/Nostalgia
2008 - FLSTSB Cross Bones
2008 - FXCW Rocker
2008 - FXCWC Rocker C
2008 - FXSTB Softail Night Train
2008 - FXSTC Softail Custom
2007 - FLHR Road King
2007 - FLHTC Electra Glide Classic
2007 - FLHTCU Electra Glide Ultra Classic
2007 - FLHX Street Glide
2007 - FXD Dyna Super Glide
2007 - FXDB Dyna Street Bob
2007 - FXDC Dyna Super Glide Custom
2007 - FXDL Dyna Low Rider
2007 - FXDWG Dyna Wide Glide
2007 - FLSTC Heritage Softail Classic
2007 - FLSTF Fat Boy
2007 - FLSTN Softail Deluxe/Heritage/Nostalgia
2007 - FLSTSC Softail Springer Classic
2007 - FXST Softail
2007 - FXSTB Softail Night Train
2007 - FXSTC Softail Custom
2007 - FXSTD Softail Deuce
2007 - FLHRC Road King Classic
2007 - FLHRS Road King Custom
2007 - FLHT Electra Glide
2007 - FLTR Road Glide
2006 - FLHR Road King
2006 - FLHTC Electra Glide Classic
2006 - FLHTCU Electra Glide Ultra Classic
2006 - FLHX Street Glide
2006 - FXD Dyna Super Glide
2006 - FXDB Dyna Street Bob
2006 - FXDC Dyna Super Glide Custom
2006 - FXDL Dyna Low Rider
2006 - FXDWG Dyna Wide Glide
2006 - FLST Heritage Softail
2006 - FLSTC Heritage Softail Classic
2006 - FLSTF Fat Boy
2006 - FLSTN Softail Deluxe/Heritage/Nostalgia
2006 - FLSTSC Softail Springer Classic
2006 - FXST Softail
2006 - FXSTB Softail Night Train
2006 - FXSTD Softail Deuce
2006 - FXSTS Softail Springer
2006 - FLHRC Road King Classic
2006 - FLHRS Road King Custom
2006 - FLHT Electra Glide
2006 - FLTR Road Glide
2005 - FLHR Road King
2005 - FLHTC Electra Glide Classic
2005 - FLHTCU Electra Glide Ultra Classic
2005 - FXD Dyna Super Glide
2005 - FXDC Dyna Super Glide Custom
2005 - FXDL Dyna Low Rider
2005 - FXDWG Dyna Wide Glide
2005 - FXDX Dyna Super Glide Sport
2005 - FLSTC Heritage Softail Classic
2005 - FLSTF Fat Boy
2005 - FLSTN Softail Deluxe/Heritage/Nostalgia
2005 - FLSTSC Softail Springer Classic
2005 - FXST Softail
2005 - FXSTB Softail Night Train
2005 - FXSTD Softail Deuce
2005 - FXSTS Softail Springer
2005 - FLHRC Road King Classic
2005 - FLHRS Road King Custom
2005 - FLHT Electra Glide
2005 - FLTR Road Glide
2004 - FLHR Road King
2004 - FLHTC Electra Glide Classic
2004 - FLHTCU Electra Glide Ultra Classic
2004 - FXD Dyna Super Glide
2004 - FXDL Dyna Low Rider
2004 - FXDWG Dyna Wide Glide
2004 - FXDX Dyna Super Glide Sport
2004 - FLSTC Heritage Softail Classic
2004 - FLSTF Fat Boy
2004 - FXST Softail
2004 - FXSTB Softail Night Train
2004 - FXSTD Softail Deuce
2004 - FXSTS Softail Springer
2004 - FLHRC Road King Classic
2004 - FLHRS Road King Custom
2004 - FLHT Electra Glide
2004 - FLTR Road Glide
2003 - FLHR Road King
2003 - FLHTC Electra Glide Classic
2003 - FLHTCU Electra Glide Ultra Classic
2003 - FXD Dyna Super Glide
2003 - FXDL Dyna Low Rider
2003 - FXDWG Dyna Wide Glide
2003 - FXDX Dyna Super Glide Sport
2003 - FXDXT Dyna Super Glide T-Sport
2003 - FLSTC Heritage Softail Classic
2003 - FLSTF Fat Boy
2003 - FLSTS Heritage Softail Springer
2003 - FXST Softail
2003 - FXSTB Softail Night Train
2003 - FXSTD Softail Deuce
2003 - FXSTS Softail Springer
2003 - FLHRC Road King Classic
2003 - FLHT Electra Glide
2003 - FLTR Road Glide
2002 - FLHR Road King
2002 - FLHTC Electra Glide Classic
2002 - FLHTCU Electra Glide Ultra Classic
2002 - FXD Dyna Super Glide
2002 - FXDL Dyna Low Rider
2002 - FXDWG Dyna Wide Glide
2002 - FXDX Dyna Super Glide Sport
2002 - FXDXT Dyna Super Glide T-Sport
2002 - FLSTC Heritage Softail Classic
2002 - FLSTF Fat Boy
2002 - FLSTS Heritage Softail Springer
2002 - FXST Softail
2002 - FXSTB Softail Night Train
2002 - FXSTD Softail Deuce
2002 - FXSTS Softail Springer
2002 - FLHRC Road King Classic
2002 - FLHT Electra Glide
2002 - FLTR Road Glide
2001 - FLHR Road King
2001 - FLHTC Electra Glide Classic
2001 - FXD Dyna Super Glide
2001 - FXDL Dyna Low Rider
2001 - FXDWG Dyna Wide Glide
2001 - FXDX Dyna Super Glide Sport
2001 - FXDXT Dyna Super Glide T-Sport
2001 - FLSTC Heritage Softail Classic
2001 - FLSTF Fat Boy
2001 - FLSTS Heritage Softail Springer
2001 - FXST Softail
2001 - FXSTB Softail Night Train
2001 - FXSTD Softail Deuce
2001 - FXSTS Softail Springer
2001 - FLHT Electra Glide
2001 - FLTR Road Glide
2000 - FLHR Road King
2000 - FLHTC Electra Glide Classic
2000 - FXD Dyna Super Glide
2000 - FXDL Dyna Low Rider
2000 - FXDS Dyna Convertible
2000 - FXDWG Dyna Wide Glide
2000 - FXDX Dyna Super Glide Sport
2000 - FLSTC Heritage Softail Classic
2000 - FLSTF Fat Boy
2000 - FLSTS Heritage Softail Springer
2000 - FXST Softail
2000 - FXSTB Softail Night Train
2000 - FXSTD Softail Deuce
2000 - FXSTS Softail Springer
2000 - FLHT Electra Glide
2000 - FLTR Road Glide
1999 - FLHR Road King
1999 - FLHTC Electra Glide Classic
1999 - FXD Dyna Super Glide
1999 - FXDL Dyna Low Rider
1999 - FXDS Dyna Convertible
1999 - FXDWG Dyna Wide Glide
1999 - FXDX Dyna Super Glide Sport
1999 - FLHT Electra Glide
1999 - FLTR Road Glide

Product Specifications

Estimated Horsepower Gain 6.05 HP @ 5206 RPM
Air Filter Color Red
Air Filter Height 1.625 in (41 mm)
Air Filter Inside Diameter 6.188 in (157 mm)
Air Filter Material Cotton Gauze
Air Filter Outlet Shape Not Flanged
Air Filter Shape Round
CARB EO Number D-269-35/55
Clamp Material No Clamps Required
Clamp Style No Clamps Required
Clamps Included No Clamps Included
Color Red
Filter Material Cotton Gauze
Inlet Diameter 2.25 in (57 mm)
Mounting Hardware Included Yes
Neck Flange 2.25 in (57 mm)
Overall Height 1.688 in (43 mm)
Product Box Height 4.88 in (124 mm)
Product Box Length 11.75 in (298 mm)
Product Box Width 9.5 in (241 mm)
Product Style Motorcycle Intake System
Replacement Filter E-3972
Size 7 Inch
Street Legal In All US States See Application Link Above
Style Oval
Top Material/Finish Black Powder Coated
Top Style Metal
TUV Approved (Europe) No
Weight 3.3 lb (1.5 kg)
Horsepower gains based on similar vehicle dynamometer test. Results will vary.

Designed to increase horsepower & torque
Dyno-tuned velocity stack
Washable and reusable
Excellent air filtration
K&N's RK Series was developed to get more horsepower from your Twin Cam Harley-Davidson engine. Built around the legendary K&N High-Flow Air Filter, the this RK Series assembly includes an innovative powder coated billet aluminum back plate that eliminates external breathers and features a built-in, dyno-tuned velocity stack. The result is a significant airflow increase to the engine without sacrificing filtration. This RK Series assembly retains a factory appearance by utilizing the stock air cleaner cover.

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