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  1. #1
    Pwgsx's Avatar
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    Adjusting Accelerator Pump

    I have a 99 gsx limited with the following jetting:

    95 piolets
    165 mains
    2.3 N/S w/ the stock 95 gram spring
    1 1/2 on the low speed adusters
    1 turn out on the front high speed screw
    1 1/8 on the rear high speed screw


    How do I adjust the Acc Pump to half?? Do I screw the jam nut in or out?? And whats the easiest way to do this with the carbs on the ski??


  2. #2
    SURFnTURF's Avatar
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    Quote Originally Posted by Pwgsx View Post
    I have a 99 gsx limited with the following jetting:

    95 piolets
    165 mains
    2.3 N/S w/ the stock 95 gram spring
    1 1/2 on the low speed adusters
    1 turn out on the front high speed screw
    1 1/8 on the rear high speed screw


    How do I adjust the Acc Pump to half?? Do I screw the jam nut in or out?? And whats the easiest way to do this with the carbs on the ski??
    To start off your prop has to be stock with exactly 13-19 blades with a good wear ring .
    You are way too rich with your settings. You can't set up the carbys to use the acc pumps only by half (whats the point). Either its using them or not.
    If your not using them I have these. 92.5 lows set approx 1 1/2 turns out with 165 highs both closed with stock N/seat and spring.

    If you are using acc pumps 82.5 lows set approx 1 1/2 turns out with 165 highs both closed stock N/ seat and spring.

    Both set ups run without the internal fuel filters inside the carbys with prok airfilters.

    If you are feeling a little raunchy with a stock set up including proks i have used 162.5 highs and even 160 highs with fantastic midrange top end power but you live closer to the edge .Revs can be up near the limiter 7100-7140 but Going back to 165s you loose a little top end but i prefer to have this than nip a piston in a tight full noise hard turn.

  3. #3
    Pwgsx's Avatar
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    So I should dissable it completely?? Whats the easiest way to do that with the carbs on the ski??

    I had the MPEM remapped to a +2 on the timing and this was the jetting he said to do along with the acc pump to half. But the more I read they say to kill the pump totally.

  4. #4
    PEST!'s Avatar
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    jetting is very subjective. Everyone has a different idea of whats right. Best to learn how to set it up and do it your way. IMHO

  5. #5
    Pwgsx's Avatar
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    this is true, anyone have tips or ideas how to adjust this while on the ski??

  6. #6
    96XPSS's Avatar
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    I'm running 90 pilots, and adjusted my pump screw out probably 50% to give me perfect throttle response. Are you running any other mods like head or different prop?

    The accelerator pump on carbs is an excellent idea. Their reason for doing it was to meet emissions. But, in their greed, this made for an overly lean condition when out of the water. ALL stock carbed 951's will lean rev on the trailer, and ignorant owners don't know to simply pull the choke. I'd hate to think how many thousand engines were compromised because of this. Way to go BRP!

    So mine is jetted rich enough not to lean rev, and the pumps supply the perfect amount of additional fuel when needed...to make it launch like a rocket consistently, every time. Two strokes love to be rich on the bottom, and the idea with non-pumped carbs was to get it rich enough to make it launch hard. But...in this tuning setup, it would also foul plugs, especially if you had to idle in no-wake zones for a long period of time. The pump does away with this nusiance, and gives excellent fuel economy too.

    My XPL consumes the same rate of fuel as an RXP when running wot, and gets better fuel economy cruising below 5k.

  7. #7
    PEST!'s Avatar
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    If you do alot of running in no wake Zones then 85 pilots and pumps if no pump 95 pilots. There is no way to get 50 % on the pump. The squirters or nozels would need to be made smaller. Limit the stroke on the pump only shortens the length of time the squirt lasts.. The main jets need to be varied also to keep the over all jetting right for WFO since both jets effect the WFO setting. There are nice threads on carb settup at the top of this page

  8. #8
    mine if I remember correctly
    1 turn lows
    95 lows
    acc pump screw in 2 full turns to lessen its affect
    stock highs
    not sure on n/s but I think 2.5 with stock spring
    proks w o/w
    held that thing wot for 20 minutes, and hit hard off bottom with stock prop

  9. #9
    96XPSS's Avatar
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    I think you are backwards on the adjustment. You go out (ccw)to decrease the amount it pushes against the diaphram.

  10. #10
    Pwgsx's Avatar
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    Quote Originally Posted by 96XPSS View Post
    I think you are backwards on the adjustment. You go out (ccw)to decrease the amount it pushes against the diaphram.

    so the jam screw goes out to decrease the amount the acc's pumps diaphram is pushed in??

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