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  1. #1
    superramjet's Avatar
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    Accel. Pumps Bypass

    I'm have trouble with the accel pump on a gp1200r and would like to just bypass it instead of buying parts to fix it. Does anybody have a link to the proper jetting? I've searched but can't find it. Thanks in advance. Tom


  2. #2
    All hail the Chief! fullboogie's Avatar
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    SRJ,

    First tell us what mods you have on the ski. There's a generally accepted set of jetting, n/s, and adjuster screw specs, but it's for someone who's done the "first round" of mods - like free flow, flame arrestors, D plate, and maybe a prop.

  3. #3
    Moderator RX951's Avatar
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    Rejetting for Flame Arrestors Stock Jetting Rejet

    Most of the people running stock carbs that disable the accelerator pump will typically have these mods below.

    These few mods can be all or some such as these below:

    Compression bump est. 140-150 psi
    D-plate (Catalytic convertor Removal)
    Free Flow

    The jetting is
    1.5 N&S "dull spring"
    110 pilot
    120 mains
    Accelerator pump disabled on stock carbs with aftermarket F/A's.

    Prok F/A's are what I run.

    Stock jetting is N&S 1.2 / pilot 95 / mains 117.5

    I would also consider filling the carb manifold channels to help increase the carb's signal for each carb.
    http://www.greenhulk.net/forums/show...=carb+manifold
    Last edited by RX951; 02-27-2007 at 07:46 PM.

  4. #4
    superramjet's Avatar
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    Sorry for that lack of info. I figured it out though. I didn't realize there was check valves inside the elbows right before the squirt nozzles. Mine were gummed up from sitting. I was just going to elimate the whole setup on a stock gpr I'm selling but don't need to now.


    Thanks for taking the time to post the infomation, i've saved it and will probably use it on the next one.

  5. #5
    Autosport's Avatar
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    Why do people remove the accelerator pump? isn't it there for a purpose?

    The only time you don't really need it is in race aplication when you're holding full throtle 99.9% of the time, but I don't understand why you would remove it on the average recreational ski?

  6. #6
    yz450f's Avatar
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    because it doesent really help that much and it is prone to gettin stuck and costing money to replace every year
    so its better and cheaper to remove it and re jet to compensate for the removal

  7. #7

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    Quote Originally Posted by Autosport View Post
    Why do people remove the accelerator pump? isn't it there for a purpose?

    The only time you don't really need it is in race aplication when you're holding full throtle 99.9% of the time, but I don't understand why you would remove it on the average recreational ski?
    The OEM jetting is pretty lean in the midrange, if your cruising around 4k-5k rpms for an extended period....it can cause an engine seizure.

    That is why people remove it

  8. #8
    Moderator OsideBill's Avatar
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    Quote Originally Posted by superramjet View Post
    I'm have trouble with the accel pump on a gp1200r and would like to just bypass it instead of buying parts to fix it. Does anybody have a link to the proper jetting? I've searched but can't find it. Thanks in advance. Tom
    http://greenhulk.net/forums/showthread.php?t=70129

  9. #9
    WATER WOODY's Avatar
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    Yamaha actually leaned the mid out for a reason and added the acc pump.Even though its a 2 stroke,it still has to pass a certain emission test(federal).Yamaha's GP1200R motor was tested and tests were taken in the mid range as an 'average' throttle position.This is how Yamaha made it work.

    Sounds crazy? its true.

  10. #10
    Moderator beerdart's Avatar
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    Quote Originally Posted by WATER WOODY View Post
    Yamaha actually leaned the mid out for a reason and added the acc pump.Even though its a 2 stroke,it still has to pass a certain emission test(federal).Yamaha's GP1200R motor was tested and tests were taken in the mid range as an 'average' throttle position.This is how Yamaha made it work.

    Sounds crazy? its true.
    Come on you are pulling the Wool over my eyes.

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