K&N RK-3909-1 vs RK-3910-1 kit...HELP! - Harley Davidson Forums: Harley Davidson Motorcycle Forum
LinkBack Thread Tools Display Modes
post #1 of 4 (permalink) Old 12-12-2012, 12:43 PM Thread Starter
Senior Member
kg5ie's Avatar
Join Date: Sep 2012
Location: Weatherford, TX
Posts: 110
Images: 1
K&N RK-3909-1 vs RK-3910-1 kit...HELP!

OK, here is my conundrum. I found a EXCELLENT buy on both of these intake kits. But the sale ends tomorrow so I have to jump now. Both use the stock air cleaner cover.

But...one uses a 9" element the other uses a 7". The 9" element is also 5/8" taller than the 7" so that will move the cover out that much.

Has anyone who has used the larger kit found it uncomfortable in that interferes with your leg position while riding?????

Bill D.
2009 FLSTC
kg5ie is offline  
Sponsored Links
post #2 of 4 (permalink) Old 08-12-2013, 10:31 AM
Senior Member
nexttime's Avatar
Join Date: Feb 2013
Location: Bel Air
Posts: 124
nexttime is offline  
post #3 of 4 (permalink) Old 08-13-2013, 06:13 PM
pawpaw01's Avatar
Join Date: Nov 2009
Location: Odessa, Texas
Posts: 57
I had the 3909 kit and it is a fair improvement over the stock air cleaner. I have now installed the 3910 kit and it has a mildly thicker filter. I have not had any issues with knee placement or comfort. The 3909 kit will flow more than enough air for a mild build (like mine) but I had to have the thicker filter..... Good luck with either one you choose.
Remember, Ride Safe..

2008 FXSTC, V&H BSS, K&N AC kit, SE255 cams,
ThunderMax w/AT, Superbrace
Remember, Ride Safe...
pawpaw01 is offline  
post #4 of 4 (permalink) Old 08-14-2013, 01:53 PM
Join Date: Mar 2013
Location: Dallas
Posts: 394
As a side note, I just put the 3909-1 kit on my FXST. Dynoed it before and after, no
difference whatsoever (it has a jet kit in it already).
mattchalmers is offline  

Quick Reply

Register Now

In order to be able to post messages on the Harley Davidson Forums: Harley Davidson Motorcycle Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome