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  1. #1
    rick xp's Avatar
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    The right prop for a XPL

    Hey,

    I have just changed my setup on my boat from twin pipes to the stock single pipe and im wondering what prop i should run.

    My mods are....

    * R & D head with 49cc domes running 150 psi
    * Aftermarket reeds and intake manifold on stock carbs.
    * R & D Airfilter
    * Stinger reduced down a fraction.

    Im currently running a skat trak 14 vein D-75 setback pump and im turning 7400 RPM with a shit holeshot with an alright top speed but you hit a corner and the thing slows right down. Its the 148mm prop version.

    What do you recommend?


  2. #2
    rick xp's Avatar
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    Also do you know if a solas prop can fit in to a skat trak pump?

  3. #3
    m schmidt's Avatar
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    What prop and nozzle size are you running now?

  4. #4
    96XPSS's Avatar
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    Quote Originally Posted by rick xp View Post
    Also do you know if a solas prop can fit in to a skat trak pump?
    No, and you need to disclose what prop pitch you are currently running and both nozzle sizes...like previously mentioned.

    Did you just bolt the pipes and pump on, rejet, and this is what you have? How much stuff did you change at one time?

  5. #5
    rick xp's Avatar
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    My ski at the moment just has R&D head with 49cc domes running at 150 PSI. Aftermarket reeds and filters and is now running the stock pipe.

    I have a skat trak 14 vein setback pump 148mm prop. It has a skat trak 16/24

    Now my question is am i running the wrong prop for this setup?

    Im turning this prop at 7400 RPM with an ok holeshot.

  6. #6
    96XPSS's Avatar
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    There are guys here that have run your setup, sorry I don't have accurate advice. BigboreXPL and others may see your post and advise you.

    We still don't know what nozzle sizes you are trying to stuff the water through...all this is very relevant. You are turning this prop 7400 with a stock pipe? Hmm...

    The rule of thumb is you just decreased your HP substantially by removing the pipes. You didn't disclose what rpms you turned it with the pipes, unless that is the 7400 number you mention. It's hard to advise you at all until you give us all the information necessary...

  7. #7
    rick xp's Avatar
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    sorry for the confusion. I had the twin pipes on the boat but i pulled them off because i couldnt get them dialed in right.

    At the moment i am running 7400 RPM through a 84mm venturi and stock nozzle and running a 16/24 Skat Trak Prop.

    This boat has....

    R&D Head with 49cc domes
    Modified MPEM with 8k Rev limit
    Stock pipe
    Aftermarket flame arrestors and reeds.
    Skat trak 14 vein setback pump.

    Im just wondering if i am running the right prop?

    The boat pulls pretty good but is 7400 RPM too high for stock pipe?

  8. #8
    96XPSS's Avatar
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    No rpms are too high for any pipe, if you can get the speed, then rpms = excellent HP you are making. You may be melting couplers drying out the pipe that much too. Otherwise, you are underpropped.

    It laying down in the corners has me wondering if you are jetted too lean on your low speeds?

    I've never heard a stock pipe turning those rpms. So you may be underpropped. Do you have a stock pump & prop to install for performance comparison? This would eliminate tuning issues and then you could determine where to go with the prop.

    IMO...the prop is not actually bent at a true 16/24. I would think you would turn less max rpms than you are if bent correctly.

  9. #9
    rick xp's Avatar
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    The prop looks untouched. I ran this prop on my twins and i only pulled 7400 on those as well.

    The prop i think is too tall on the bottom end and maybe that is the reason the boat slows down when turning?

    I dont have a stock pump to try it but i raced a GPR a couple of days ago and i know that boat had done 67 GPS and i passed him him with ease.

    My jetting is 120 lows and 162.5 highs with the screws half a turn out. Acc pumps disconnected.

    Pistons and plugs look mint and burning correctly but on a hard turn i can hear a bit of ticking sound coming from the engine. Im going to try race gas today and see if it goes away. The timing is advanced on 2. I think im running a 2.3 NS and 95 gram spring.

  10. #10
    96XPSS's Avatar
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    I think the prop may be too tall also. Did you buy it from Skat? They have sent me brand-new props nowhere near what is stamped on the side. After two wrong ones I do all my business with David @ Impros. Any new prop you buy from him, he checks it for correct pitch and balance. Every other prop I have ever bought from somone else has been out of pitch, one blade off...etc.

    Your low speeds jets may be too big also. Is that suggested jetting for the twins? I've heard of guys running 100 on the lows with the pumps disconnected, but I don't recall ever hearing 120. I'm running 80's/170's on my 00XP with pumps, but it lean revs. I'm going to 90 pilots this winter.

    I'd try the race gas like you said before rejetting leaner...just to see if it is detonating. This would be a big indicator on being overpropped.

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