Pre-filter or not on EFI 990

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by knobbyjoe, Jan 10, 2013.

  1. knobbyjoe

    knobbyjoe knobbyjoe

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    To pre-filter or not on EFI 2008 990 Adventure<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:p></o:p>
    <o:p></o:p>
    Yes I have search and been reading about replacing the snorkel with a pre-filter. But have not been able to figure out the consequences to the A/F mix with EFI. I want to keep the bike stock only trying to protected the engine and give the air box filter a chance.<o:p></o:p>
    <o:p></o:p>
    The story: Just disassembled the bike for the first valve check at 15,000. There is too much dust and grit in the air box and a little bit inside the fuel injector side of the air filter. The filter was dirty and obviously past due to be replaced. I did notice a loss of pep while passing at speed.<o:p></o:p>
    <o:p> </o:p>
    The question: If I run the pre-filter will I have adverse performance or loss of gas mileage? Or is it just plug and play and won't even know I have a pre-filter installed?<o:p></o:p>
    <o:p> </o:p>
    Thanks Knowledgably gurus of the air/fuel mystical world <o:p></o:p>
    #1
  2. DSM8

    DSM8 Where fun goes to die....

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    Short answer is do it.

    The benefits outweigh any disadvantage like loss of deep water crossings etc (like really deep).

    I did it to mine and consider it a necessity if you do any sort of off road and dusty riding.

    And no I didnt bother to remap afterwards either. But if you do it will be better from what I hear (I went to carbs).
    #2
  3. KTMADV

    KTMADV Hammer Down

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    I have a 2007 ktm 990 adventure with a home made filter and its not bad and bike runs great.

    Look up ktm 990 pre filter on advrider. I have pictures.
    #3
  4. knobbyjoe

    knobbyjoe knobbyjoe

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    KTMADV,
    I want to, but "Home made Filter?" A link please. Are you saying you are the person that modified your pre-filter. Please the suspense. Tell me what you think. Some had questions about that and didn't get a final conclusion. Thanks KJ
    #4
  5. KTMADV

    KTMADV Hammer Down

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    What I meant to say was I used a Harley Davisdon pre filter and bolts with the back plate. I just cut out the air box and snorkle and made a little bottom plate and put it togeather.

    I like it because you just use water to clean it or if you use oil on it you just use a K@N cleaner plus oil. If you use the oil it attracts more dust.. The filter does not move from the base plate because it has a lip on it. Here is a link of my pre filter very easy and cheap to do. Not bad on the dyno either

    http://advrider.com/forums/showthread.php?t=837678
    #5
  6. knobbyjoe

    knobbyjoe knobbyjoe

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    KTMADV,
    I have read that several times. Looks good. Looks like I'd need to order some parts. When you get the time would you mind listing the parts and where to order?
    Thanks KJ
    #6
  7. KTMADV

    KTMADV Hammer Down

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    I think the parts came off a 2000 Harley Davidson FLH Touring FLHPI police air breather with parts. I would have to take my filter off and go to my Harley Davidson shop to get the right part #s to post. You just have to make the little black plate that goes in the snorkel.


    Its all very easy to do. It only took my three hours from start to finish to make plus a 12 pack of Newcastle beer.
    #7
  8. catalina38

    catalina38 Long timer

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    I did a few long rides (6000 miles) with identical 2010 990R's same exhaust, stock R map with the unifilter prefilter on one and the other with stock snorkle. They got nearly identical gas mileage, no noticeable difference in performance. The bike with the prefilter required it to be cleaned several times during those rides but kept the main filter cleaner longer. After the 6000 miles the more frequent maintenance became a PITA. More work overall for not much benefit. After this first hand experience I decided not to install one and he was going to remove it at the next filter replacement. YMMV.
    #8
  9. Hondo

    Hondo What if it's a Samsquamch?

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    I replaced the snorkel with a Uni prefilter (wetted with No Toil) & it is wrapped with a filterskin.

    No remap, runs great - 2011 990 Adventure.
    #9
  10. Apple Jam

    Apple Jam Forest Flyer

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    I put the UNI prefilter on 2 years ago. Stock filter still in place.
    I had nothing to compare with,
    but it did not seem faster/better, nor any mileage difference.
    Intake sounded slightly noisier in a good way,
    but the hassle factor of needing more cleaning, more often, is not really worth it.
    I will either remove it or clean it, and not re-oil it.
    #10
  11. 950TRANSALP

    950TRANSALP Been here awhile

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    get a bunch of " filter skins " and swap them out when dirty . 1 to 2k mi. .
    this keeps the Uni clean .
    #11
  12. laramie LC4

    laramie LC4 crash test dummy!

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    hahahah! nice avitair 950transalp, where ya get it? :evil looks a lot like my old one. :lol3

    back on topic, i just put a filter skin over the snorkle. not sure how much it is helping since i haven't checked it yet (only got a few 100 miles on it), but it's got to be better than nothing.

    laramie :beer
    #12
  13. 950TRANSALP

    950TRANSALP Been here awhile

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    Did you oil the skin ?

    if that was your graphic thanks !
    #13
  14. laramie LC4

    laramie LC4 crash test dummy!

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    nope. just stuck it over the top. i have always been told to leave the skin dry so that the dirt doesn't stick. anything that gets through will get trapped by the oil and foam, or in this case the paper.

    laramie :beer
    #14
  15. Brown Town

    Brown Town Been here awhile

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    I'm looking at my snorkel right now :evil and the angle of it looks very different than the angle of the UNI filter. Will it fit? (Bring on the innuendos.)

    Any wet weather concerns for the UNI vs. snorkel?
    #15
  16. zeegman

    zeegman Been here awhile

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    #16
  17. Brown Town

    Brown Town Been here awhile

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    Ok I just installed the UNI and it's being bent back slightly by all the cables, is this normal?

    Also, I found a large cable off to the left folded back on itself with two separate connectors that isn't connected to anything. The larger connector is booted and the smaller one isn't. HELP!
    :kboom
    #17
  18. zeegman

    zeegman Been here awhile

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  19. Brown Town

    Brown Town Been here awhile

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    [​IMG]
    #19
  20. Brown Town

    Brown Town Been here awhile

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    The two connectors on the blue towels were tucked up front where their cables originate. They're actually routed towards the rear on the left side of the frame where they are fastened and then double back to the front but are connected to nothing. :huh
    #20