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. The RK-3910-1 comes with a larger air filter and longer spacers than the RK-3909-1.

This Part Fits:

Year	Make	Model	Submodel
1999-2007	Harley-Davidson	FLHR Road King	Base
2007	Harley-Davidson	FLHRC Road King Classic	Base
2002-2006	Harley-Davidson	FLHRCI Road King Classic	Base
2003-2006	Harley-Davidson	FLHRI Road King	Base
2004-2007	Harley-Davidson	FLHRS Road King Custom	Base
2004-2006	Harley-Davidson	FLHRSI Road King Custom	Base
1999-2007	Harley-Davidson	FLHT Electra Glide Standard	Base
1999-2005,2007	Harley-Davidson	FLHTC Electra Glide Classic	Base
2002-2006	Harley-Davidson	FLHTCI Electra Glide Classic	Base
2007	Harley-Davidson	FLHTCU Electra Glide Ultra Classic	Base
2002-2006	Harley-Davidson	FLHTCUI Electra Glide Ultra Classic	Base
2003-2006	Harley-Davidson	FLHTI Electra Glide Standard	Base
2006-2007	Harley-Davidson	FLHX Street Glide	Base
2006	Harley-Davidson	FLHXI Street Glide	Base
2006	Harley-Davidson	FLST Heritage Softail	Base
2000-2012	Harley-Davidson	FLSTC Heritage Softail Classic	Base
2002-2006	Harley-Davidson	FLSTCI Heritage Softail Classic	Base
2000-2012	Harley-Davidson	FLSTF Fat Boy	Base
2010-2012	Harley-Davidson	FLSTFB Fat Boy Lo	Base
2001-2006	Harley-Davidson	FLSTFI Fat Boy	Base
2006	Harley-Davidson	FLSTI Heritage Softail	Base
2005-2012	Harley-Davidson	FLSTN Softail Deluxe	Base
2005-2006	Harley-Davidson	FLSTNI Softail Deluxe	Base
2000-2003	Harley-Davidson	FLSTS Heritage Springer	Base
2005-2007	Harley-Davidson	FLSTSC Softail Springer Classic	Base
2005-2006	Harley-Davidson	FLSTSCI Softail Springer Classic	Base
2001-2003	Harley-Davidson	FLSTSI Heritage Springer	Base
1999-2002,2007	Harley-Davidson	FLTR Road Glide	Base
2002-2006	Harley-Davidson	FLTRI Road Glide	Base
2010-2011	Harley-Davidson	FLTRX Road Glide Custom	Base
2008-2009	Harley-Davidson	FXCW Rocker	Base
2008-2011	Harley-Davidson	FXCWC Rocker C	Base
1999-2007	Harley-Davidson	FXD Dyna Super Glide	Base
2007	Harley-Davidson	FXDB Street Bob	Base
2006	Harley-Davidson	FXDBI Street Bob	Base
2005,2007	Harley-Davidson	FXDC Super Glide Custom	Base
2005-2006	Harley-Davidson	FXDCI Super Glide Custom	Base
2004-2006	Harley-Davidson	FXDI Dyna Super Glide	Base
2006	Harley-Davidson	FXDI35 Dyna 35th Anniversary Super Glide	Base
1999-2005,2007	Harley-Davidson	FXDL Dyna Low Rider	Base
2004-2006	Harley-Davidson	FXDLI Dyna Low Rider	Base
1999-2000	Harley-Davidson	FXDS-Conv Dyna Convertible	Base
1999-2007	Harley-Davidson	FXDWG Dyna Wide Glide	Base
2004-2006	Harley-Davidson	FXDWGI Dyna Wide Glide	Base
1999-2004	Harley-Davidson	FXDX Dyna Super Glide Sport	Base
2004-2005	Harley-Davidson	FXDXI Dyna Super Glide Sport	Base
2001-2003	Harley-Davidson	FXDXT Dyna Super Glide T-Sport	Base
2000-2009	Harley-Davidson	FXST Softail Standard	Base
2000-2009	Harley-Davidson	FXSTB Night Train	Base
2001-2006	Harley-Davidson	FXSTBI Night Train	Base
2007-2010	Harley-Davidson	FXSTC Softail Custom	Base
2000-2007	Harley-Davidson	FXSTD Softail Deuce	Base
2001-2006	Harley-Davidson	FXSTDI Softail Deuce	Base
2001-2006	Harley-Davidson	FXSTI Softail Standard	Base
2000-2006	Harley-Davidson	FXSTS Springer Softail	Base
2001-2006	Harley-Davidson	FXSTSI Springer Softail	Base