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  1. #1
    5.0. alex_baker202's Avatar
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    Impeller pitch or reduction insert?

    New mods made my 14/19 hit the rev lim at 67.4. I noticed it reached this speed about 7900 and 3/4 throttle. L temp 39. E temp 59. 4 bars full.

    I was wondering if I should try repitching or a reduction ring. Maybe 83mm. The good thing is I have a machine shop to reduce the ring if I order big. But I'm not sure how easy it is to tune the impeller. I also assume every-time I pull the nozzle to take the impeller out I have to re-silicone the wedge??


    Any suggestions ?


  2. #2
    Having Fun jp1300r's Avatar
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    The stock RXP exit nozzle is 83mm already. I don't re-silicone the wedge just put it back together.

  3. #3
    Wait until the weather warms up and run it again. That prop should be ok for the mods you have. If you are only turning 7900, you are not on the limiter. I would put a different wheel in the charger, then you could go to a 15/20. Worked for me and made good gains.

  4. #4
    5.0. alex_baker202's Avatar
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    No at 7900 I reach the top speed then after that the throttle puts it to 8100 and 8150. That's how I figure I'm on the limiter. So what nozzle would I start with if the stock is 83. I thought stock was 81 but I may be wrong.

  5. #5
    b_dolla44's Avatar
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    Stock is 83mm. I would just get a 15/20r.....then when you upgrade your sc you wont be back tracking...

  6. #6
    5.0. alex_baker202's Avatar
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    Should I try to repitch or just buy new

  7. #7
    dduck dduck1628's Avatar
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    Quote Originally Posted by alex_baker202 View Post
    Should I try to repitch or just buy new
    I’m kinda new to impeller pitch tweaking. Of the handful that I have measured, some impellers were all over the place right out of the box, some pretty close. Recently I measured an untouched 14/19 at an average pitch of 13/16.5. This prop came off a ski that was bumping the rev limiter with the stock SC too. In my experience a 14/19 that is somewhat accurately pitched is a bit much for the 215 hp SC /IC in the FL heat. That said, I'd pay one of the reputable “impeller guru” members on this site to check it out and make a recommendation. It's the only way to be sure.

  8. #8
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    You got 2 options...

    1) Pitch the 14/19 a few mm's, after truing up all the blades equally first...
    2) Go either 15/20 four blade, or 15/19 three blade...

    But remember you are riding in unusual temps, the cold water will make any ski bang the limiter when in summer trim...I would not do anything until it gets warmer water...

    On a side note, I had a 14/19 in my ski originally when I got it. Put in an XS and 4" intake, was all over the limiter with a stock SC...Swapped a 15/19 in there and it was spot on...I suggest you get rid of the 3" in favor of a 4", its a 77% gain in air volume.

  9. #9
    5.0. alex_baker202's Avatar
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    So has n e one heard of tuning with the nozzle rings. I'm thinking this would be easier that Impeller pitching and I can change them from summer or winter depending on conditions

  10. #10
    MSRXP's Avatar
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    Problem you will run into with tuning with rings is over stuff of the pump. Be careful and go one size at a time to find out what works for your setup. Bailing at 65+ especially at 39 degree temps hurts.

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