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Has anyone tried using a RU-2970 K&N air filter?

Discussion in 'The Garage' started by oldgeek, Oct 16, 2011.

  1. oldgeek

    oldgeek XS400 Enthusiast

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    I have been researching air filters since mikesxs is out of the 57mm ones that fit my carbs.

    I came across the dimensions for the RU-2970. I believe it might just fit in the small space directly off of the carbs.
    It is a dual inlet, single filter. The inlets are 60mm and the center to center is 106mm.
    The center to center i measured on my carbs is about 110mm

    I originally wanted to use the stock rubber inlet tubes, and put filters on the ends of them, but on closer inspection the tubes are in poor condition.
     
  2. oldgeek

    oldgeek XS400 Enthusiast

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    Well, I took the chance and ordered it. The filter came in, and as you can see it seems to fit fine. I found one on Amazon, for $30.09 including shipping, which I think is a great deal for any K&N filter. The filter will definitely flow more air than just about any other setup, not that it matters in my application. I think it looks pretty good overall. I also got the rotor cover in, and made the gasket for it...progress is slow! (the kitchen repairs are finished!)

    [​IMG]
    [​IMG]
    [​IMG]
     
  3. bcware

    bcware Well-read Top Contributor

    Awesome. I may have to go this route myself. Is there room for a crank case breather under this filter?
     
  4. drewpy

    drewpy Excess twin Top Contributor

    that's cool, i did see that before and wondered if it fitted!
     
  5. oldgeek

    oldgeek XS400 Enthusiast

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    I think so.

    [​IMG]
    [​IMG]

    Obviously, i had to move all wiring out of the way to get it in there.:laugh:
     
    Brit In Czech likes this.
  6. Awesome, I've been wanted to take another route instead of using 2 pods. A single unit is more what I wanted. Great find, thanks a ton.

    Posted via Mobile
     
  7. cudacrazy73

    cudacrazy73 XS400 New Member

    I know this is an old thread, and Im new so sorry. but where is your battery then?
     
  8. Lasse

    Lasse XS400 New Member

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    After reading this thread, i bought this airfilter too, and i am very pleased with it

    I found a alternative battery and gave it a new location :)
    After cutting away a bit of plastic.
    [​IMG]

    [​IMG]

    I cut away 6 mm of the airfilter rubber mountings. This way the lip inside the filters will sit flush with the carburetor intake. :thumbsup:
    [​IMG]
     
  9. jvdavidson

    jvdavidson '78 XS400-2E

    Lasse, just out of curiousity, what are the specs on that battery - can't quite read it. I've been looking at doing just that with my battery but was not sure if those type batteries could handle the current draw of headlights + ignition + turnsignal + tail light etc...

    Gotta see Denmark one of these days - a few years ago I learned my last name (Davidson) was originally Davidsen (obviously Danish) but Elis Island botched it when my ancestors came to the U.S.

    Cheers!

    - James
     
  10. levdir

    levdir Rounded bolt brigade

    I'm running a 1.5 aH 12v AGM battery even smaller than that one and have had no problems, but my bike is kick only. I actually removed the starter relay in the process of wiring in the terminals for the battery. If you want to retain e-start it will be difficult to keep a battery like that healthy.
     
  11. xschris

    xschris XS400 Guru Top Contributor

    The biggest thing with the smaller batteries is the charge cycle of it. These bikes put out 14.5-7 volts at 5k rpm's. A lot of the little batteries can't take that much and get fried after a while. My 80 has a 1.2ah sealed acid battery that I have been using for 3 years in this bike and 2 years in one of my razz's with about 6k miles total and still holds 12.6v after sitting for weeks. It sat all last winter (in a warm dry basement) without any charge and still had 12.5v come spring. Not bad for a $9 battery. :laugh:
     
  12. rugbywarrior89

    rugbywarrior89 Need more time...

    I was wondering, since there is a ton of air flow from that type of filter, could you fill in every other "notch" (for lack of a better term) with some type of filler like maybe JB weld or RTV or something? I would think that would cut down quite a bit on airflow. Thoughts?
     
  13. xschris

    xschris XS400 Guru Top Contributor

    Sure you could but your better of going stock or jetting to match.
     
  14. Lasse

    Lasse XS400 New Member

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    HereĀ“s the specs on the battery
    http://ultracell.net/datasheets/UL2.4-12.pdf

    It's 2.4AH capacity and i have no problems with powerloss (kick start only)


    A last name ending with "-sen" sounds very danish i agree, that's also the case with my own last name :)
     
  15. Normand

    Normand XS400 Member

    After some years, how is it going with the air filter? Did you rejet or keep your cabrs stock? Do you recommend it?
     
  16. Unkle Crusty

    Unkle Crusty XS400 Enthusiast

    I am doing the same kind of thing. But I just cut out the front of the air box, so the battery can stay in the same place. Have two EMGO filters to pick up next time I am on the mainland. I will check to see how much water gets sprayed around the filters. If too much I will change to the double foam type filter. They should not mind touching the frame, located just above the filters. I have 4 1/8 inches from the carbs to the filter box. I will use a longer piece of rubber tubing for the crank vent and locate it elsewhere on the air box. Later I may change to a small filter directly to the crank casing. If there is room. I have main jets in 117.2 122.5 125 127.5 130 and 140.
    First test will be with the 125 in each carb. Mine is a DOHC motor. 83 Seca.

    Unkle Crusty
     
  17. GFAlexandru

    GFAlexandru Two Wheels One Life

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    Hello,
    My name is Alex, I know this is an old topic but I hope someone will find this post and help me

    I've recently bought an 1981 XS400 Special 4G5 and I've mounted K&N RU-2970 air filter on it.
    Did you guys rejet the carbs ?
    Can you please tell me what modifications should I make to run well ?
    Sorry for my bad english...
    Thank you !
     
  18. Doug Smith

    Doug Smith XS400 Member

    xschris likes this.
  19. xschris

    xschris XS400 Guru Top Contributor

    For most people's motors OEM is best.
     
    Doug Smith likes this.

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