Kinda disappointed with a heavily modified 750 - Page 5
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  1. #41
    PWCToday.com Is My Home Away From Home cavemanX2650's Avatar
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    Re: Kinda disappointed with a heavily modified 750

    It takes a good amount of work besides just putting a bigger engine in to make it work right , as said before the biggest issue holding you back right now is AIR IN and OUT ,.. stock hood air inlets are way to small to feed a 750 ,. not only that but the stock x2 exhaust outlet is way too small , and the x2 pump tunnel is horrible ,.. here is a video of mine , she was a monster ..

    ported 750 small pin

    185psi

    46mm SBN single

    650 Factory Performance pipe

    PJS waterbox with 2'' rear exit

    Top hood blow off vents removed with a cap over the carb to keep water out (for tested purpose)

    650 lightweight Jetnetics flywheel

    650 Dales Bad Attitude CDI

    Pump tunnel mod (there are threads on here about it)

    13/18 cut back stock SXR impeller

    https://youtu.be/CoHLAzXc3gs

    Last edited by cavemanX2650; 02-15-2018 at 04:49 PM.


  2. #42
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: Kinda disappointed with a heavily modified 750

    Quote Originally Posted by vocalDyslexic View Post
    Took to lake and it ran flawlessly, with one issue. It pulls nowhere near as hard as it did in
    the iPro. The pro even has a more top speed oriented swirl.

    I put the only skat i had for a 650, the 15.5 in thinking top speed will be a lot less, but was under the impression that it should
    pull harder till it hits the x2 wall.

    It doesn't at all tho. I'm trying to figure out what to do to change this.
    Modify the sxi impeller to fit in a 650 pump.

    Quote Originally Posted by vocalDyslexic View Post
    This newmiller 750 has to be over 100 with the FPP, but in the x2 it seems only slightly more than
    the modded 650 that i had in my other x2.
    Chris should be able to help you with determining a max rpm goal. Then purchase
    a decent tachometer.

    Quote Originally Posted by vocalDyslexic View Post
    I am a fat azz and need a powerplant that can compensate for my poor eating habbits which is why im
    trying to keep increasing power till the power to my weight ratio is dramatically improved since that
    increase can take much less time than a decrease in my weight.
    When you get old and fat I recommend you put more effort in finding a set-up with a smooth
    power delivery. It will prevent you from becoming a floating or drowning physics experiment


    Quote Originally Posted by 01GS View Post
    From my understanding the stock hood doesn’t flow very well even with a 650.
    It doesn't, except when you have a bad set-up, that restrictive hood can prevent your
    ski from melting down!

    Quote Originally Posted by vocalDyslexic View Post
    I thought about that but never came back to it. Probably should open jt up a bit before season.

    I'm sure the combination of the 650 Coffman, the stock airflow hood, and the drastically wrong impeller pitch all came together to make the issue worse.
    A great example of a set-up that should not modify the hood any time soon.

    Restricting the airflow on a new or unknown set-up is a great tuning tip.

    Quote Originally Posted by vocalDyslexic View Post
    I stopped thinking air intake once i got it all lined out and we determined that a full throttle hit from off idle was spinning the impeller
    quicker than the impeller could move water,
    Rock Damaged impeller.

    Quote Originally Posted by vocalDyslexic View Post
    and then on top end it would get to a point and wouldn't rev and further, until pump came unloaded out of water the accelerate hard
    for a sec once loaded but then same thing.
    An over-pitched impeller.

    Quote Originally Posted by vocalDyslexic View Post
    Looking fwd to spring now to see how much more violent the new pipe, new dual 46's, and more airflow will be.
    Sounds like a great opportunity to blow something up.



    Bill M.

    Hard hitting pipes hit hard because they just lost a bunch of HP in the rpm before the pipe hits!
    Last edited by wmazz; 02-20-2018 at 05:33 AM.
    Horsepower == Speed, RPM != Speed



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