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Supplier details checked 2026-09-23 · Test catalog
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The latest addition to K&N's RK Series was developed to get more horsepower from your Twin Cam Harley-Davidson engine. Provides a significant airflow increase to the engine without sacrificing filtration.
Intake System-Harley Davidson
Washable & Reusable Air Filter: Includes a High-Flow Air Filter that can go up to 100,000 miles before cleaning under normal highway driving conditions.
Designed to increase horsepower & torque
Dyno-tuned velocity stack
Excellent air filtration
Washable and reusable
Associated products: E-3972 Round Air Filter, 99-5000 Filter Care Service Kit Aerosol
K&N Red Intake System for Harley-Davidson
Air Intake System
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.
Air Cleaner Assembly
