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
Features
- Designed to increase horsepower & torque
- Dyno-tuned velocity stack
- Washable and reusable
- Excellent air filtration
Specifications
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Estimated Horsepower Gain: 10.76 HP @ 5206 RPM
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Air Filter Height: 2.188 in (56 mm)
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Overall Height: 2.188 in (56 mm)
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Inlet Diameter: 2.25 in (57 mm)
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Weight: 3.3 lb (1.5 kg)
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Top Material: Black Powder Coated
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Air Filter Material: Cotton Gauze
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CARB EO Number: D-269-35/55
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Replacement Filter: E-3980
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Top Style: Metal
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Warranty: No-Hassle Lifetime Limited
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Air Filter Color: Red
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Color / Finish: Red Filter, Metal Top
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Oil Included: Yes
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Street Legal In All US States: Not legal for sale or use in California on any pollution controlled motor vehicle. NOTE: Some specific models and years may be legal in CA. Check the CARB status on your parts at knfilters.com
