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  1. #1

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    Apr 2010
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    How to adjust the low speed screws?

    Morning,
    I just rebuilt a GP1200R and rebuilt the carbs. I put T handles on lows and highs. I also removed chokes put a/m arrestors on.

    As per a previous thread, I have put 110 lows speeds and set the low speed screws to 1 and 1/8 turns out.

    On the trailer, I have high idle speed and the idle speed is varying up down. When I rev it doesn't return to idle speed either.

    I assume the lows are too lean. However, short of pulling the stinger or becoming the rubber man does anyone have a cunning tip to adjust the low speeds in the boat?


  2. #2
    gaz1's Avatar
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    Jan 2008
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    Did you follow all the re-jetting specs,the highs and lows,springs etc.?Did you pressure test the engine and did make sure you don't have any air leaks?My re-jetted carbs ended up being 1 1/2 turns out on the lows but i don't think another 1/8 of a turn will cure it.1/8 incriments are fine tuning adjustments so i think it could be a leak.It's only 10 mins to take the exhaust off anyway(when you've done it 100 times).

  3. #3

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    Apr 2010
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    Jetting specs

    Quote Originally Posted by gaz1 View Post
    Did you follow all the re-jetting specs,the highs and lows,springs etc.?Did you pressure test the engine and did make sure you don't have any air leaks?My re-jetted carbs ended up being 1 1/2 turns out on the lows but i don't think another 1/8 of a turn will cure it.1/8 incriments are fine tuning adjustments so i think it could be a leak.It's only 10 mins to take the exhaust off anyway(when you've done it 100 times).
    It is cold here at the moment (about 10deg C), I might wind out the low speeds to 1.5 turns and see what it runs like.

    Yes I replaced n/s with 1.5 and 95g springs replaced filters armitures etc in all carbs. Highs are 135 with 1 and 1/2 turns out although haven't been on the water yet.

    I pressure tested the block (not with carbs/reeds attached) - it could be a leak on the inlet tract

    I found the stinger to be a PITA (has a jetworks mod) to get lined up and installed and it took me about 45 mins when I did it...it did take only 10 mins to remove though

  4. #4
    Moderator DrewNJ's Avatar
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    Dec 2005
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    assuming that your throttle cable isn't getting hung up and is adjusted properly it sounds like you have an air leak so time to double check your work and pull the carbs again.
    Also, the low screws are tough to reach like you said. You are either pulling the stinger or relocating the CDI box and battery.

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