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  1. #1

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    Impellor question - want more bottom

    I actually haven't rode this machine yet but my buddy (mechanic) tells me the pump stator and impellor are in rough shape. He rode it last fall before I bought the machine. Then it got too cold.

    Its a 97 or 98 Polaris 785 with a 1050 triple - all stock. Regular single pipe and stock carbs. The motor came out of an Slx. I don't know the whole story but I need to start looking for a better impellor. I have an Slx that (for sale shortly) and I have never liked it. Its got good top speed but the bottom is lame.

    I want this boat to have good bottom. I am a wave jumping guy - not a speed freak. So if I was looking to change the impellor anyway - what should I look out for?

    If anybody wants to shed some light on how to read the pitch charts etc that would be appreciated - we are simple folks up here in Canada.
    I have seen 17/24 17/25 Skat Track #7 etc? What does it all mean?

    And if you have anything I could use for sale please PM.


    thanks

    james


  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Check this out, and pay special attention to #15. Skat trak swirls are the best for bottom end performance. http://www.greenhulk.net/forums/showthread.php?t=15430

  3. #3
    www.springbreak-florida.com rgard32's Avatar
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    a skat trak 17/24 would work..

    where is the motor that came out of it????

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Arrow Impeller pitch angles

    Quote Originally Posted by omalley View Post
    ...I am a wave jumping guy - not a speed freak. So if I was looking to change the impellor anyway - what should I look out for?

    If anybody wants to shed some light on how to read the pitch charts etc that would be appreciated - we are simple folks up here in Canada.
    I have seen 17/24 17/25 Skat Track #7 etc? What does it all mean?...
    Well, here is my current understanding of impeller basics.
    Guys, correct me where I miss the mark here.

    The first number is the pitch angle, in degrees, of the leading edge of each impeller blade, at the outer circumference (where it meets the wear ring).

    The second number is the pitch angle, in degrees, of the trailing edge on each impeller blade.

    The leading edge pitch affects (among other things) the launch out of the hole, and the low-mid RPM pulling strength. Smaller numbers allow the engine to rev faster from a standstill, and produce harder acceleration.

    The trailing edge angle controls the load on the engine at higher forward speeds. As the angle gets larger, the boat goes faster, but the load on the engine increases. If the pitch is too steep, then engine will be unable to achieve peak power RPM, and you will go slower than with a less steeply pitched impeller.

    The numerical gap between the leading and trailing angles affects how much mid RPM torque will be required to get the engine up to high speed RPM. Too large a pitch difference will load the engine as RPMs try to rise, and it will struggle to gain RPM.

    Different brands of impeller also have different performance attributes, so a 12/17 from two different companies will have similar, but not the same, results.

    Impellers can also be re-pitched, where the blades are carefully bent to slightly different angles than factory. Some impellers also benefit from careful grinding to re-contour parts of the blades for best performance.

    Intake grate design and machine/rider weight can also affect impeller choice.

    Engine power and torque curve also affect impeller choice. If an engine is modified for increased power, but at higher RPM than stock, sometimes the original impeller pitch, or close, is the one to use.

    I could not suggest which impeller brand or pitch would best match your requirements, and the exact pitch will of course be affected by the actual power output of your engine. Others here have solid experience selecting impellers.

    Another item worth considering may be the AAT from WetWolf. It adjusts the jet pump stator tail cone size according to pump nozzle back pressure, and changes length automatically as impeller RPM and forward speed rises.
    Last edited by K447; 04-19-2008 at 10:49 PM. Reason: AAT info

  5. #5
    casey67's Avatar
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    Quote Originally Posted by omalley View Post

    Its a 97 or 98 Polaris 785 with a 1050 triple - all stock. Regular single pipe and stock carbs. The motor came out of an Slx. I don't know the whole story but I need to start looking for a better impellor. I have an Slx that (for sale shortly) and I have never liked it. Its got good top speed but the bottom is lame.

    I want this boat to have good bottom. I am a wave jumping guy - not a speed freak. So if I was looking to change the impellor anyway - what should I look out for?


    thanks

    james

    Hi James, I talked to Absentex( I think that is his user name) a while ago,He installed a Skat Trac 15/23 or 15/24 on his 99 SLX,he was very impressed with the hole shot,he said it was a huge improvement over the stock impeller.Send him a PM to ask exactly which imp he used.

    On my 97 SL1050,after a changed the carbs,it would do wheelies with the stock 5131686 impeller,it's not clear what that prop was,It looked like a Scat Trac,if so it would be a 14/24,either way I damaged that imp. I'm more of a top speed guy,so I've tried several imp's.As you experienced,the Skat Trac 17/25 or 7.0 Nujet did make it sluggish,but good top speed. Over the winter I bought a uncommon 15/26,I haven't tried it yet.

    In my opinion,contact Skat trac,use what they recommend for hole shot on a 1050. It will probably be what Absentx used 15/24 or some where around there.

  6. #6
    absentx's Avatar
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    PM sent regarding the prop...

    It is a 13/24 SSL which is the recommended skat prop on a stock engine.

    I am surprised though that you considered the 99 SLX's holeshot "lame" because I have considered it pretty damn good even with a nu-jet or stock prop. I wonder if maybe something else was going on?

    The 13/24 recommendation though is for the SL hull and 1050 engine, I really am not sure what would work for a 1050 in a pro 785 hull???

  7. #7

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    Thanks for the help

    I will keep my eyes open for something that fits the bill. Thanks guys for your help.

    omalley



    Quote Originally Posted by absentx View Post
    PM sent regarding the prop...

    It is a 13/24 SSL which is the recommended skat prop on a stock engine.

    I am surprised though that you considered the 99 SLX's holeshot "lame" because I have considered it pretty damn good even with a nu-jet or stock prop. I wonder if maybe something else was going on?

    The 13/24 recommendation though is for the SL hull and 1050 engine, I really am not sure what would work for a 1050 in a pro 785 hull???

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