So help me with my carb prob...

Discussion in 'OT Driven' started by Otter, Oct 3, 2007.

  1. Otter

    Otter New Member

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    Well, I bought a 2002 Harley Sportster to cruise on when I'm not riding the CBR. The only problems is the jetting must be just a tad bit off...but I can't seem to figure it out.

    Every once in a while, it just sounds like it has the slightest miss in it. Just like a psfft! from the breather...it has Screamin Eagle pipes and intake and was jetted by the dealer all before I got it. I'm not sure which jet is off...It seems to be the worst whenj I get off the interstate or sitting at a stop light for a long time.

    How do which one to replace or adjust...I hate messing with carbs...
     
  2. Coottie

    Coottie BOOMER......SOONER OT Supporter

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    Maybe it would be better to let a mechanic mess with it then. :shrug:
     
  3. 00600

    00600 New Member

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    It's a Harley, they ALL do that.

    "Ka-thump, Ka-thump, pop, Ka-thump, Ka-thump, Ka-thump, pop, Ka-thump, pop"
     
  4. DamonS

    DamonS Flyin' High Again

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    Jetting is best determined by a bog (feels like it loses power) at certain RPM's. I'm not convinced by what you describe that it's jetting.

    Personally, it sounds more like a broken or cracked intake manifold or even the manifold gasket is bad (cracked, missing or otherwise). You can try to track it down by simply spraying WD-40 on the intake manifolds, if the problem goes away, then voila!, replace boots and you're set..

    the only other thing (based on your quick description) would be that if you have 2 carb's, then they could be out of sync.. A dealer could sync them up quickly.. I caution against doing it yourself as this is something best done professionally.. out of sync carbs, cause premature engine issues.


    If you get a backfire (and i know that HD is known for them), then its in the exhaust.
     
  5. xbishopx

    xbishopx deusexaethera is a fucking idiot.

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    if its at cruising speeds when your air fuel ratio is leanest, id say the carb needs to be cleaned out, the jets are probably fine if its ONLY cutting out while at a steady throttle.

    is it a constant velocity carb?
     
  6. Ludeykrus

    Ludeykrus New Member

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    But if it's backfiring through the carbs, it would indicate a rich condition, correct? I think you're assuming it's backfiring through the exhaust...could be wrong though!
     
  7. 00600

    00600 New Member

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    Usually backfiring through the exhaust is caused by a rich condition, backfiring through the carb is caused by a lean condition or ignition timing.
     
  8. Junkie

    Junkie re-tarded OT Supporter

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    you can certainly get the exhaust to pop from a lean condition
     
  9. 00600

    00600 New Member

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    Yup, that's why I always move toward the rich side first when I'm tuning (keeps from melting pistons too), 2-4 steps richer, if it slows down/bogs then I go leaner.

    Still doesn't change the fact that the majority of exhaust backfires are caused by rich conditions/exhaust leaks.
     

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