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  1. #1
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    Default Accelerator pump adjustment

    We are talking of course about fine tuning the volume and timing of the pump squirt intended to cover the lack of fuel during a "braaaap" moment.

    This adjustment has been covered
    Instruction sheets, discussions, videos etc
    This is the adjustment at idle with a warm motor...
    Done after all other jetting and timing variables have been sorted out.
    And, of course, the only way to know if you've truly killed the "brap stumble" is a proper road test.

    The things I see that varies is peoples understanding of the word "brap"
    I know what I think it means...
    S&S uses the word "blip" and the wording "abruptly cranked fully open"
    Mikuni makes no mention of throttle technique

    In practice, while getting the initial "curb" setting...
    I see some people doing a weird double pump,
    Some do a slight, quick quarter turn of the throttle,
    Some are kind of lazy about it,
    And yet others an abrupt WOT!
    These all lead to drastically different initial settings.

    What say you, my internet friends?
    How exactly do you twist the wick during this adjustment?

  2. #2
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    Default

    I go by road test since anything else isn't a road test. I start with near no squirt then slowly increase pump stroke.

    Old "agricultural" engine designs ain't two strokes or crotch rockets so I don't harshly snap the throttle anyway, just roll it on quickly as normal.

  3. #3
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    Default

    I've wondered about this myself

  4. #4
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    If you road test each adjustment you can't go wrong.

    That's why dyno tuning exists. Dynos simulate operational loads. Any setting can be tested under conditions simulating real world use and behavior measured.

    Manufacturer literature is plentiful and a good resource for initial settings.
    Last edited by farmall; 10-12-2019 at 11:10 AM.

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