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  1. #1
    OCFZR's Avatar
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    GK 1390 BB speed poll

    Just wandering what speeds/rpm's everyone is getting out of their Group K 1390's. I'm trying to tune mine to get in the upper 70's. Please specify what props/pumps you are ruuning as well as any other mods.

    Thank you!


  2. #2
    Hydrotoys's Avatar
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    Good question.

  3. #3
    eric1238's Avatar
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    1390

    I just got mine broke in and I am at 71.5 @7320 RPMs at about 780 ft and spinning the prop out of the hole BAD. I have the 05 pump with an out of the box 14/20 and am in need of a repitch BAD. I am like you , would LOVE to see 77 to 78.

  4. #4

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    What's happening,
    I have had my ski in the garage for the past three months and just this past weekend I got my first ride since I went to Seoul, Korea last April.
    The prop is spinning out of the hole, but once it kicks in it freaking flies. My firends XPL would get about one boat out of the hole then I would fly by him after about 3 seconds. My best speed was after I burned out all the old fuel and filled it halfway with fresh fuel. 75.5 mph My friends XPL GPS'ed at 63.2 mph which is the best speed I have seen for his stock ski.

    In addition to the GK I have a J-plate(unsgegged), Advent CDI, Riva 14/21 S/B prop, Wet Wolf AAT.

  5. #5

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    Oh yeh, I was turning 7120 rpms and the the air was about 84 degrees. The humididty was around 50%.

  6. #6
    GPRPITMAN's Avatar
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    Well 05 pump dynaflt prop at a 16-26 black jack carbs advent ignition with my own hull work boat ran 81.5 at 7720 in 90 percent humidity and 94 out side

  7. #7
    flyboy's Avatar
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    Quote Originally Posted by GPRPITMAN
    Well 05 pump dynaflt prop at a 16-26 black jack carbs advent ignition with my own hull work boat ran 81.5 at 7720 in 90 percent humidity and 94 out side
    your single pipe is turning a 16/26 at 7720?!?!?!?!

    you have the strongest GPR in the World!

  8. #8
    YudLuz2's Avatar
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    Quote Originally Posted by flyboy1300
    Quote Originally Posted by GPRPITMAN
    Well 05 pump dynaflt prop at a 16-26 black jack carbs advent ignition with my own hull work boat ran 81.5 at 7720 in 90 percent humidity and 94 out side
    your single pipe is turning a 16/26 at 7720?!?!?!?!

    you have the strongest GPR in the World!
    I think the boy is all Shook up. Probably thinking
    about the rpms that his triple pipe is turning.

  9. #9

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    Haha... He probably means 7220rpms ??? Even turning a 16/26 at 7200 is some major power.
    Thats an awesome mph for a single pipe.

  10. #10
    Moderator RX951's Avatar
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    single pipe 16/26 at 7720






    :P

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