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  1. #21
    PWCToday.com Is My Home Away From Home mcn6's Avatar
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    Re: How to get more torque

    Do the compression bump first, especially if you have a stock "A" or "B" casting head. PWI requires installation of a control unit, solenoid, spray bar and a suitable area near the exhaust manifold/head pipe connection that is solid aluminum (no water jacket) to install the spray bar.



    Home of Newmiller Machine

  2. #22
    PWCToday Guru
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    Re: How to get more torque

    Quote Originally Posted by mcn6 View Post
    Do the compression bump first, especially if you have a stock "A" or "B" casting head. PWI requires installation of a control unit, solenoid, spray bar and a suitable area near the exhaust manifold/head pipe connection that is solid aluminum (no water jacket) to install the spray bar.
    as far as the connection needed would the surf beace work or does I️t need to be connected to the motor?

  3. #23
    PWCToday.com Is My Home Away From Home fastgtfairlane's Avatar
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    Re: How to get more torque

    Man play with your head pipe screws first.
    91 440; PJS Viper 7000, jetsport exhaust mani, factory full pipe, coffman waterbox,solas 17*, jetco worked 440 pump, ocean pro nozzles. shredmaster ocean rideplate and grate combo, wide tray, footholds, deep strake mod, driveshaft fill,650sx quick turn

    build thread part 1: http://www.pwctoday.com/showthread.php?t=331343
    build thread part 2: http://www.pwctoday.com/showthread.php?t=364872
    build thread part 3: http://www.pwctoday.com/showthread.php?t=396154

  4. #24
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    Re: How to get more torque

    Quote Originally Posted by fastgtfairlane View Post
    Man play with your head pipe screws first.
    I️ will haven’t been to the lake yet I️ll try that first. Appreciate the advice

  5. #25
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    Re: How to get more torque

    Also what’s your guys opinion on the r and d pump stuffer?

  6. #26
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: How to get more torque

    Do you even know how much compression your engine produces?

    Do you want to keep it running on pump gas? If so bumping up
    the compression to 185psi will only be about 10 to 15psi over
    stock.

    If you are looking to just remachine your cylinder head, that is
    a waste of money. It's not like you are going to increase the
    compression significantly, like an old pp550 that had 125psi stock.
    On the pp550 it was common to bump the compression to 175 to
    185psi (a 50 to 60psi increase).

    On a 550, there was room for a ~48% increase in compression.
    But on a 750, the pump gas limit only leaves room for a ~9%
    increase in compression.

    If you still want to increase your compression, reduce your squish
    and gain reliability and acceleration. You can do this by purchasing
    an ADA billet head, or decking your cylinder.


    But the easiest way to increase power and acceleration is to
    Reverse Jet your SXR i-body carbs. All it will cost you is a little
    time, 4 jets, 2 springs, new gaskets, and very important: use
    your stock 1.5 needle & seats.


    Bill M.
    Horsepower == Speed, RPM != Speed



  7. #27
    PWCToday.com Is My Home Away From Home
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    Re: How to get more torque

    Bill!! You are alive!!
    triceps are the biceps of the back of your arm.

  8. #28
    PWCToday.com Is My Home Away From Home theVetteman3's Avatar
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    Re: How to get more torque

    He is alive!

    Bill, do you have any guidelines on jet selection for reverse jetting the Mikunis? I'm curious how it compares to factory pipe's jetting. Which so far on a variety of flame arrestor / piped skis has been pretty good.
    1985 JS550/800 "Pretty Red": Newmiller 800, Rhaas 750 pump conv. [56.3mph gps]
    2009 1100 SJ:
    Kawi 1100 build in progress
    2009 SJ MINT:
    KP steering adaptor, Worx 228 intake [45.8mph gps]
    1987 WJ650:
    6M6, JD Intake Grate, 17/20, cheater pipe [47.8mph gps]
    1994 XiR: 830cc Superstock, PJS side draft, 13/18 swirl [53.7mph gps]
    1995 SJ MINT:
    [TBD]



  9. #29
    PWCToday.com Is My Home Away From Home theVetteman3's Avatar
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    Re: How to get more torque

    Quote Originally Posted by Mythenand View Post
    Okay so I️ll start with my ski it’s a 91 with umi, Prowatercraft ride plate, Westcoast intake grate(have a top loader to put on), 10/16 hooker, factory pipe for a 650 , 750 small pin believe I️t has unmarked cylinders, prowatercraft drive shaft fill, and Sxr carbs I’m sure I️ forgot something but that should be about I️t with me being only 17 I’ve got a little under 2000 into the hull build and I️ gpsed I️t at 52.2 while my dads 800 goes 53.2 so I’m good with top end just want to know how to get a little more torque. Things I’ve thought about is 2inch exhaust, high comp head, or lighten flywheel. Any input is welcome just don’t want my dads ski beating me so badly on bottom end lol. Thanks in advance
    For more low end torque, also consider changing pipes. The 650 factory pipe is a good all around pipe, but my friend has a dual small pin with a waveblaster factory pipe and there is definitely more low end. The whole power band is shifted down a bit, but it hits pretty hard. I believe JonnyX2 had good results with them a while ago, as do a bunch of the X2 guys. The unmarked / 750sx cylinder with that pipe has just about the most low end on a stock 750 engine that I have ever felt. And we have maybe 10 750 engines in various skis in our riding group we can try back to back.

    Also low end/ freestyle porting. For most recreational riding that's the porting you want. Good results for the dollars you invest. With all those mods, unless you dad is running a ton of mods on a ported 800, you'll be decently enough out of the hole faster than him, that a 1-2mph advantage wont matter much. The 800s were only 5hp more, and have middle of the road port timing stock.
    Last edited by theVetteman3; 05-09-2019 at 06:57 AM.
    1985 JS550/800 "Pretty Red": Newmiller 800, Rhaas 750 pump conv. [56.3mph gps]
    2009 1100 SJ:
    Kawi 1100 build in progress
    2009 SJ MINT:
    KP steering adaptor, Worx 228 intake [45.8mph gps]
    1987 WJ650:
    6M6, JD Intake Grate, 17/20, cheater pipe [47.8mph gps]
    1994 XiR: 830cc Superstock, PJS side draft, 13/18 swirl [53.7mph gps]
    1995 SJ MINT:
    [TBD]



  10. #30
    PWCToday.com Is My Home Away From Home john zigler's Avatar
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    Re: How to get more torque

    Quote Originally Posted by wmazz View Post
    Do you even know how much compression your engine produces?

    Do you want to keep it running on pump gas? If so bumping up
    the compression to 185psi will only be about 10 to 15psi over
    stock.

    If you are looking to just remachine your cylinder head, that is
    a waste of money. It's not like you are going to increase the
    compression significantly, like an old pp550 that had 125psi stock.
    On the pp550 it was common to bump the compression to 175 to
    185psi (a 50 to 60psi increase).

    On a 550, there was room for a ~48% increase in compression.
    But on a 750, the pump gas limit only leaves room for a ~9%
    increase in compression.

    If you still want to increase your compression, reduce your squish
    and gain reliability and acceleration. You can do this by purchasing
    an ADA billet head, or decking your cylinder.


    But the easiest way to increase power and acceleration is to
    Reverse Jet your SXR i-body carbs. All it will cost you is a little
    time, 4 jets, 2 springs, new gaskets, and very important: use
    your stock 1.5 needle & seats.


    Bill M.
    Sorry, respectfully, I totally disagree...

    Increasing compression 10-15 psi makes a noticeable difference in throttle response, and low end acceleration. Maybe not a HUGE difference, but very noticeable, and is part of an overall package.

    That, and reverse jetting IMO does not work. It is fine for a freestyle ski that is set up for all bottom end, and never sees WOT, but NOT in a rec set up.
    RCJS also doing business as WATCON
    608-743-1305 9am to 5pm CST m-f
    email watcon@watcon.com

    Please visit our web site

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