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K&N RK-3909-1 Intake System-Harley Davidson

Custom Assemblies > Intake System-Harley Davidson
  • 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. The RK-3910-1 comes with a larger air filter and longer spacers than the RK-3909-1.

[More Information on High-Flow Air Intake Systems for Harley-Davidson Motorcycles]

Product Specifications

Estimated Horsepower Gain6.05 HP @ 5206 RPM
Air Filter ColorRed
Air Filter Height1.625 in (41 mm)
Air Filter Inside Diameter6.188 in (157 mm)
Air Filter MaterialCotton Gauze
Air Filter Outlet ShapeNot Flanged
Air Filter ShapeRound
CARB EO NumberD-269-35/55
Clamp MaterialNo Clamps Required
Clamp StyleNo Clamps Required
Clamps IncludedNo Clamps Included
Filter MaterialCotton Gauze
Inlet Diameter2.25 in (57 mm)
Mounting Hardware IncludedYes
Neck Flange2.25 in (57 mm)
Overall Height1.688 in (43 mm)
Product Box Height4.88 in (124 mm)
Product Box Length11.75 in (298 mm)
Product Box Width9.5 in (241 mm)
Product StyleMotorcycle Intake System
Replacement FilterE-3972
Size7 Inch
Street Legal In All US StatesSee Application Link Above
Top Material/FinishBlack Powder Coated
Top StyleMetal
TUV Approved (Europe)No
Weight3.3 lb (1.5 kg)
Horsepower gains based on similar vehicle dynamometer test. Results will vary.

K&N RK-3909-1 Intake System-Harley Davidson Product Reviews