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

    --
    Posted using the http://www.motorcycleforumz.com interface, at author's request
    Articles individually checked for conformance to usenet standards
    Topic URL: http://www.motorcycleforumz.com/Tech-XJ750-Pilot-Mixture-Adjustment-ftopict136385.html
    Visit Topic URL to contact author (reg. req'd). Report abuse: http://www.motorcycleforumz.com/eform.php?p=7483224
     
    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



    stageleft Wrote:
    > 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
    >
    > --
    > Posted using the http://www.motorcycleforumz.com interface, at author'
    > request
    > Articles individually checked for conformance to usenet standards
    > Topic URL: http://tinyurl.com/oyc62
    > Visit Topic URL to contact author (reg. req'd). Report abuse
    > http://www.motorcycleforumz.com/eform.php?p=748322



    --
    baz666
     
    baz666, Jul 29, 2006
    #2
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  3. stageleft

    FB Guest

    Why are you responding to threads that are a year old?

    baz666 wrote:
    > the factory setting of the pilot mixture screws is usually about 1 turn
    > out from bottom.


    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

    Re: Why are you responding to threads that are a year old?

    On 29 Jul 2006 19:45:06 -0700, "FB" <> wrote:

    >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?


    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
    --
    '73 CB450K
    '82 CB900F (x2)
    '04 FSC600 (SWMBO)
     
    Scott, Jul 30, 2006
    #4
  5. stageleft

    FB Guest

    Re: Why are you responding to threads that are a year old?

    Scott wrote:

    > 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.


    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

    Re: Why are you responding to threads that are a year old?

    "FB" <> wrote in message
    news:...
    >
    > Scott wrote:
    >
    >> 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.

    >
    > 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

    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    :eek:)


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

    HRMayo

    Joined:
    Mar 4, 2015
    Messages:
    1
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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:
    Jun 2, 2017
    Messages:
    1
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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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