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K&N RK-3910-1 Intake System-Harley Davidson

Custom Assemblies > Intake System-Harley Davidson
Rating Star 1 Rating Star 2 Rating Star 3 Rating Star 4 Rating Star 5   4.9 out of 5 stars   22 Customer Reviews
  • 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 Gain10.76 HP @ 5206 RPM
Replacement FilterE-3980
Air Filter ColorRed
Air Filter MaterialCotton Gauze
Product StyleMotorcycle Intake System
Size9 Inch
Air Filter ShapeOval
Air Filter Height2.188 in (56 mm)
Air Filter Outlet ShapeRound
CARB EO NumberD-269-35/55
Street Legal In All US StatesSee Application Link Above
TUV Approved (Europe)No
Inlet Diameter2.25 in (57 mm)
Overall Height2.188 in (56 mm)
Top StyleMetal
Top MaterialBlack Powder Coated
Clamps IncludedNo Clamps Included
Clamp StyleNo Clamps Required
Clamp MaterialNo Clamps Required
Weight3.3 lb (1.5 kg)
Product Box Height4.88 in (124 mm)
Product Box Length11.75 in (298 mm)
Product Box Width9.5 in (241 mm)
Couplers IncludedNone
Mounting Hardware IncludedYes
Neck Flange2.25 in (57 mm)
Horsepower gains based on similar vehicle dynamometer test. Results will vary.

K&N RK-3910-1 Intake System-Harley Davidson Product Reviews

Monday, December 18, 2017 - Part RK-3910-1
Well Packaged as it had some distance to travel. Did exactly what you said it would, easy to fit even for a office worker. Impressed I Be.

Vince Gardner
Geraldine, New Zealand
Monday, November 6, 2017 - Part RK-3910-1
Installed K-3910-1 on my 2007 Road King Classic, Install was relatively easy. Instructions were adequate, could use a bit more detail. My old Screaming Eagle air intake had lines coming out of the breather bolts back into the throttle body. No explanation of this type of set-up. Would have been helpful to know why K&N uses the set up they do. When replacing the stock AC cover, the design of the filter, which has a plastic circular ring to space it, The plastic cracked with a few turns of the AC Cover bolt. Does not effect anything, but a bit unnerving to hear a loud crack. Also, Instructions do not specify if the filter should be oiled at installation. The filter fits great, works just as it states and a power gain can be felt. Highly recommend the product.

Demetrius Barkoukis
Franklin square, New York
Friday, September 15, 2017 - Part RK-3910-1
This high flow intake system was very easy to install and has made a marked improvement in my bike's performance.

Brian Dallas
London, Canada
Wednesday, May 24, 2017 - Part RK-3910-1
This purchase went superbly from beginning to end. The order was easy to do online. I got to watch my package make it's way across the continent to me.....incredibly fast. I opened the box, bolted it on with no issues. It was a perfect fit and easy to mount with excellent instructions and all the pictures I needed. As for performance.....we tuned the bike to the new air intake and the dyno numbers were up almost 14 HP. I'm really VERY satisfied.

Phil Miller
Glen Robertson, Canada
Monday, May 1, 2017 - Part RK-3910-1
I bought this hoping too fit to my HD softail heritage flstci 2008. Whilst trying too fit it, it quickly became apparent it would not fit after one of the locating holes pulled out. I took photo's of the damage and sent them to you. A technician named David contacted me, and to cut a long story short, I have now sent it back and I am awaiting a refund . I have no problems with anyone at K&N, service excellent from the girls who answer the phone to the correspondence with David. It's just a shame it did not fit. therefore loss off one star.

Derek Clarke
Southampton, United Kingdom
Wednesday, December 7, 2016 - Part RK-3910-1
Awesome Product. Finally got that sock out of my intake.

Chad Brown
Irondale, Alabama
Friday, November 11, 2016 - Part RK-3910-1
Wonderful product, sold by a wonderful company. I orders the wrong air filter for my 2006 Road King. I contacted the company and they made immediate actions for me to return the wrong air filter. Their salesman even helped me get the correct filter ordered. I love doing business with this company!

Mustang, Oklahoma