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  1. #1

    12F top speed issue???

    Hello there, new to the forum and also new to PWCs.

    I just purchased a pair of used 2005 STX-12Fs and everything is working great, but on both of them will only hit 40mph flat out on open water. Both of them have no problem hitting 7000rpm.

    After reading, and talking to some people I believe they should be topping out at a lot higher speed. I am wondering if anyone may have some advice or suggestions.

    Like I said, both of them seem to run exactly the same. The motors have not issues getting to 7000rpm. I checked the impellers, the one has some minor wear. They are both off "SLO" mode. and have around 90 hours of use.

    I don't now much about PWC but I'm assuming that if the engine is getting to speed the issue should be in the impeller? I also find it weird if there is an issue both of the skis are having exactly the same problem.


    Id love to hear what you guys have to say.


  2. #2
    Take the time to smile sirbreaksalot's Avatar
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    Ignore dash speed , try gps on your phone

  3. #3
    At current top speed the ski's speedo is reading 40mph and the gps is reading around 35-38mph. Still no where I feel like it should be.

  4. #4
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Check the rideplate, intake grate, pump, pump liner, and nozzles. You should be 7000-7400 stock.

    Sean

  5. #5
    boudin's Avatar
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    Quote Originally Posted by justind724 View Post
    I just purchased a pair of used 2005 STX-12Fs and everything is working great, but on both of them will only hit 40mph flat out on open water. Both of them have no problem hitting 7000rpm.
    For reference, a stock 12f should GPS in the low to mid 50s.

  6. #6
    I've got a pair of 05's as well and they both speedo at 55mph.

    I would say upload a video with sound so we can hear what it's doing. Sounds like cavitation, normal RPM but no speed.

    If your getting instant throttle response and it goes to 7k+ RPM within a couple seconds then the engine is performing properly.

    Inspect the pump from both ends very well, usually the damage is at the rear part of the impeller blades.

  7. #7
    Mine did about 55mph or so with the speedo.

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