RK-3931 - K&N Custom Assemblies, Intake System-Harley Davidson direct from K&N

K&N RK-3931
Custom Assemblies > Intake System-Harley Davidson

Your Price: $242.03

Find a Local Dealer

In Stock & Ready to Ship! Free Ground Shipping!

K&N Air Cleaner Assemblies are designed to get more horsepower from your Harley-Davidson® motorcycle. These air cleaner assemblies replace the stock air filter and backplate with an oversized K&N Air Filter and custom aluminum backing plate. These assemblies utilizes the stock cover to maintain stock appearance. [MORE]

Available Information

Installation Instruction Sheet

Air Filter Test Data

Dyno Chart - 2008 Harley Davidson Dyna Street Bob 6.54HP Increase

News Story - Add 6.5 More Horsepower to Harley Davidson Dyna Models with K&N Custom Intake Assembly

RK-3931 Vehicle Applications

Part RK-3931 Product Specifications
Product Style: Motorcycle Intake System
Estimated Horsepower Gain: 6.54 HP @ 5100 RPM
Street Legal In All US States: No
TUV Approved (Europe): No
Air Filter Shape: Unique
Clamp Style: No Clamps Required
Color: Red
Filter Height: 2.125 in (54 mm)
Filter Material: Cotton Gauze
Neck Flange: 2.4 in (61 mm)
Overall Height: 2.5 in (64 mm)
Replacement Filter: E-3975
Size: 9 Inch
Top Material/Finish: Aluminum
Top Style: Metal
Total Height: 2.5 in (64 mm)
Weight: 3.1 lb (1.4 kg)
Product Box Length: 11.75 in (298 mm)
Product Box Width: 9.5 in (241 mm)
Product Box Height: 4.88 in (124 mm)

Horsepower gains based on similar vehicle dynamometer test. Results will vary.

Accessories

99-5050 - Filter Care Service Kit - Squeeze

E-3975 - Replacement Filter

Product Reviews Review part RK-3931

Coming from Southern Calif. as I do I have been a big fan of K&N air filters for a long time and today was no exception. I just finished installing the RK-3909 air cleaner/filter kit and I must say I was not only impressed with the hardware and the way everything went together and fit perfect but the step by step instructions (with photos) were great. You see writing instructions is something I know a little about as a retired aerospace Mfg. Engineer I wrote instructions for the guys making the parts as well as putting together of rockets and all types of aircraft.
2007 Harley Davidson 96ci Softail Model Nightrain
Well done and thank you,
Lee Champagne, Orcas, Washington

My 2008 Colorado Crew Cab was great - until you had to put your foot in it and pass someone. I had always heard good things about K&N and the benefits to horsepower and acceleration. The filter to fit my vehicle's 3.7 liter engine had not even been released yet, but I told my local dealer to order it as soon as it was available. The difference in performance was immediate. The acceleration is now everything that it should be, and is completely responsive to what I need it to do. I have become an advocate for K&N and recommend them anytime I get the chance. A friend didn't hesitate in taking my advice when it came to upgrading his new Harley Davidson Dyna Glide! Kudos on a job well done!!!
Gary Lewis, Memphis, Tennessee

Dear K&N:
I have been using K&N products since about 1974, and I love them! I have used the air filters in my Harley Davidsons over the years with tremendous results. I worked as a Harley mechanic in Battle Creek, Michigan and saw the benefits of the form-fitting air filters, particularly in motorcycles that were laid up over the winter months. The rains, dirt and mud on the outside of the filter did not penetrate the excellent filtration to the inside of the engine. I was often amazed at how clean the inside of engines were when a K&N filter (& my own PCV adaptation) were fitted. When I moved to Florida in 1979, I worked for both the Ft. Lauderdale and the Miami Harley Davidson franchises as a mechanic. Even with that treacherous sugar sand of southern Florida, the inside of engines was clean and grit free when fitted with K&N filters. I am now anxiously awaiting the release of the filter for my 2008 105th Anniversary Edition FLHTCU with fuel injection.

Keep up the good work, K&N, and hurry up with that new filter kit for my Ultra Classic!

Best wishes for a blessed and prosperous 2008.

Sincerely,
George Laws, Aubundale, Florida

K&N RK-3931 fits the following:

2013 HARLEY DAVIDSON FXDWG DYNA WIDE GLIDE 103 CI - All