XJ750 Pilot Mixture Adjustment

Discussion in 'Motorbike Technical Discussion' started by stageleft, Jul 31, 2005.

  1. stageleft

    stageleft Guest

    I’ve recently bought an 83 XJ750 and am having considerable
    difficulity with carb adjustments - specifically 1 & 4 are doing fine,
    2 & 3 are running rich.

    I’ve had the carbs cleaned, replaced the needles and jets, had the
    carbs sync’d (vacum tube) twice, checked all the rubber boots for
    cracks, have made multiple float level adjustments and checked the
    levels against with what the manual says they should read on a tube,
    and while each adjustment nets some little bit of improvement I am
    quickly coming to the conclusion that the previous owner may have
    tinkered with the pilot mixture adjustment screws.

    Unfortunately the Haynes manual says little more than "these are
    pre-set" and "do not touch", and dealers mutter archane words about
    horrible and dire consequences when asked. I would like to know what
    the factory pre-set is so I can check to see if that is what they are
    set to but this information seems to have a higher classification than
    most mortal riders can hope to attain, even Mr. Google has been of no
    help to me.

    I have considered checking where 1 and/or 4 are set and seeing if 2 &
    3 are at least in the general neighbourhood - is this a workable plan?

    Does anyone know what the factory pre-set is?

    Thanks

    M
     
    stageleft, Jul 31, 2005
    #1
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  2. stageleft

    baz666 Guest

    the factory setting of the pilot mixture screws is usually about 1 tur
    out from bottom.
    That is too lean but used to pass emission regulations.
    The optimum setting for the XJ750 is between 2 and 2.5 turns out fro
    bottom.
    So pull out those little rubber caps and bottom each screw carefully
    There's a tiny spring in there so don't reef on it. Just gently botto
    it, then carefully turn each one out to between 2 and 2.5 turns. You'l
    like the result...
    thx,
    baz
     
    baz666, Jul 29, 2006
    #2
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  3. stageleft

    FB Guest

    Why are you responding to threads that are a year old? It's far too
    late to help the original poster, he;s never going to read your reply,
    so why bother answering an old thread?
     
    FB, Jul 30, 2006
    #3
  4. stageleft

    Scott Guest

    Generalize much? I still have articles I posted in 1999 earmarked in my
    newsreader. If someone posts a follow-up to one of them, I'll see it.

    In any case, a follow-up to an old article may still help *someone* who is
    searching the archives for information, if not the OP. As long as it's
    topical and relevant, why get your shorts into a knot? Frankly I find the
    belated responses a lot less annoying than your whining about them.

    -Scott
     
    Scott, Jul 30, 2006
    #4
  5. stageleft

    FB Guest

    I seriously doubt that reading late follow up posts to a thread that is
    even a month old ever does anybody any good.

    Threads that go on and on and on become more and more trollishly
    argumentative than informative, and they waste the time of people who
    are actually interested in helping the original person who had the
    TECHNICAL problem.

    When the OP *never* responds to any helpful advice whatever, all effort
    expended in trying to help him/her is wasted.

    So why dredge up old posts?
     
    FB, Jul 30, 2006
    #5
  6. stageleft

    Pete M Guest

     
    Pete M, Oct 14, 2006
    #6
  7. stageleft

    HRMayo

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    I'll be darned, here it is 2015 and your antique post helped me out on something I forgot.
    Thanks for posting!!
     
    HRMayo, Mar 4, 2015
    #7
  8. stageleft

    Sawyer

    Joined:
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    Now it's 2017 and the reply from 2006 helped me set the pilot mixture after a rebuild. 2 turns back is great!
     
    Sawyer, Jun 2, 2017
    #8
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