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2000 Harley still backfires

Discussion in 'Motorcycle Tech Talk' started by fr68, Sep 8, 2010.

  1. fr68

    fr68 Member

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    Last fall my bike had the same problem, overhauled carb, still a problem, rejetted and problem was corrected. Was unable to ride until now and problem is back. It backfires under light acceleration, especially when first taking off or tipping into throttle at cruising speeds. Also when setting still and reving it up slowly it's not smooth and backfires thru carb.

    Thanks
    fr68, Sep 8, 2010
    #1
  3. kenfuzed

    kenfuzed Administrator Staff Member

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    Try backing out the mixture screw (or EZ-Just) 1/8th turn.
    kenfuzed, Sep 8, 2010
    #2
  4. yin

    yin New Member

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    I had an issue with my carb sneezing also. I noticed it happened when my idle was set too low. The carb would load up and poof. I like my idle low so I was just easy on the throttle. It's not so much of an issue now with the new breather set up Im running with. Sometimes it will sneeze (usually on a cold start), but very seldom.

    Im no tech, but its just something I noticed. And I know Im well under the shop manuals recommended idle rpm. I would set the idle to spec and it seemed to stop, but I didnt like the sound of it and it felt like it was too high.
    I like the shake rattle and roll.
    yin, Sep 8, 2010
    #3
  5. chucktx

    chucktx Moderator Staff Member

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    a too low of an idle will destroy your engine......lack of oil to the upper end...........set at factory specs. to make it last a while..............
    chucktx, Sep 8, 2010
    #4
  6. cowboy

    cowboy Moderator Staff Member

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    yep chuck is right on that , these newer engines are not like the old shovel or pan's
    cowboy, Sep 8, 2010
    #5
  7. yin

    yin New Member

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    Dang. Ill have to tell the guys at work.
    Seems its a wide spread trend here.
    Everyones idle is set way low.
    yin, Sep 8, 2010
    #6
  8. fr68

    fr68 Member

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    Have curb idle set way up, thinking that was the root cause to start out with and have adjusted mixture screw to different settings at least a half dozen times, road testing each time and stopping to make ajustments with no success. Note: Performance at wide open throttle is great
    fr68, Sep 9, 2010
    #7
  9. chucktx

    chucktx Moderator Staff Member

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    check for vacuum leaks...........
    chucktx, Sep 9, 2010
    #8
  10. cowboy

    cowboy Moderator Staff Member

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    fr68 what year & model bike are we talking about here ? & what if any mod's have been made ie Pipes /open air clearner /cam's This info will help us all out trying to help you out
    The twin cams need to idel around 1 k
    cowboy, Sep 9, 2010
    #9
  11. fr68

    fr68 Member

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    cowboy,

    it's a 2000 deuce with a keihin carb. Other than the screaming eagle air cleaner kit that was installed (air cleaner, carb rejet and exhaust baffles cut out, it's a stock bike. As noted, i overhauled the carb last fall, ended jetting it @ .50 and it run fine. Have checked it for vacuum leaks, none found. Idle speed is a little over 1k and as noted before, it coughs on tip in acceleration at highway speeds

    thanks
    fr68, Sep 9, 2010
    #10
  12. hotroadking

    hotroadking Super Moderator Staff Member

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    Sounds like a lean cough, this can be from improper jetting, improper setting of the Air mix screw or a leak.

    First check for any intake leaks - eliminate the possibilities is the goal.

    Take a propane torch and don't light it but get bike warmed up
    and open torch and hold around intake seals, see if idle changes,

    Propane works best because it won't make a mess.

    Check exhaust bolts make sure there are no leaks there, once
    you know it's sealed properly , then work on the carb settings.
    hotroadking, Sep 9, 2010
    #11
  13. Tomflhrci98

    Tomflhrci98 Active Member

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    Ya know, since this bike is 10 years old - ifn it was me - I would just go and change out the intake seals, carb seals, vacuum line to the VOEs and the line to the tank valve. Any of that can leak and sometimes it aint that easy to find leaks. These things are cheap insurance.

    You may want to get a Mighty Vac tool and check for leaks at the VOEs and Tank valve. Maybe one of those has failed.
    Tomflhrci98, Sep 10, 2010
    #12
  14. fr68

    fr68 Member

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    fr68, Sep 26, 2010
    #13

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