How to get more torque
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  1. #1
    PWCToday Guru
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    How to get more torque

    Okay so I️ll start with my ski itís 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 Iím sure I️ forgot something but that should be about I️t with me being only 17 Iíve got a little under 2000 into the hull build and I️ gpsed I️t at 52.2 while my dads 800 goes 53.2 so Iím good with top end just want to know how to get a little more torque. Things Iíve thought about is 2inch exhaust, high comp head, or lighten flywheel. Any input is welcome just donít want my dads ski beating me so badly on bottom end lol. Thanks in advance

  2. #2
    PWCToday.com Is My Home Away From Home bandit88's Avatar
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    Re: How to get more torque

    Higher comp head and a lightened flywheel is a good start. For ease and reliability find a 750 D stamp head, with the small pin cylinder that will bring you to 170-175ish psi, which is perfect for 91 pump gas.
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  3. #3
    PWCToday.com Is My Home Away From Home john zigler's Avatar
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    Re: How to get more torque

    Head, flywheel, timing, AND 2" exh are all good things, and will increase bottom end throttle response.
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  4. #4
    PWCToday.com Is My Home Away From Home fastgtfairlane's Avatar
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    Re: How to get more torque

    Definitely milling the head will make a big difference. Lightened flywheel will help the ski rev quicker but it's not gonna be a very dramatic increase. Since you have a factory pipe, you can play with the water screws that will change the tuned length of your pipe. The 650 chamber on the 750 engine is gonna be more like a top end hp setup anyways. I've got a very similar setup as you with a #22 cylinder, milled head, lightened flywheel, sbn 44 and hooker 9/15. I started playing with the water screws and saw a dramatic increase in bottom end after opening the screws. I started with just the top opened 3/4 turn and ended up with 2 turns on the top screw and 1/2 turn open on the middle and it has lots of bottom end torque now. I'd recommend playing with your water tuning on the pipe first since it's free and you could do it anytime. Open the screws until you notice the top end fall off the on close whatever screw you opened last a 1/4turn back in. more water in the pipe= more low end torque, less water= more top end hp
    Last edited by fastgtfairlane; 04-20-2019 at 08:20 AM.
    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

  5. #5

    Re: How to get more torque

    What cdi are you running?The kawi part#3738 cdi has great advance and good retard up top. Power comes in hard. Came stock in 94 XiR and 98-02 Sxi pro.

    I saw a decrease in acceleration when I had the Prowatercraft stuffer in the pump cavity.
    Last edited by 2strokesmoke; 04-20-2019 at 08:22 AM.

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

    Water injection can help also, you can do this with your head pipe or add a unit from MSD or Microtouch. I run this on two of my Kawi motors and both have factory pipes, they work well.
    Never argue with an idiot, they will drag you down to their level then beat you with experience.

  7. #7
    I dream skis
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    Re: How to get more torque

    What RPM are you turning topped out on flat water in 100 feet?

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

    I'm running a 750sp, ADA head bumped to only about 10psi more than stock, lightened flywheel, 10/16 hooker, 650sx style nozzles (removed the trim), 1" spacer, 87mm bored nozzle, the extended PJS rip turn, stock pump cone, R&D 750 pipe, 94/95 waterbox, every bit of the exhaust is 2", RCJS intake grate, and a sbn44.

    I have yet to actually test my build, however, it was built not for top speed but for quick bursts/surf. I would think your best first mods for your desired application would be to bump compression a little bit and lighten the flywheel as stated above.


  9. #9
    PWCToday.com Is My Home Away From Home mcn6's Avatar
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    Re: How to get more torque

    All good information in this thread... Compression increases produce almost all torque so probably want to start with what bandit mentioned. If you are running the stock "A" casting head that came stock with the #20 cylinders you are leaving a lot of bottom end grunt on the table. And like that fairlane character mentioned, check that your water injection bleeds are not clogged and tune the head pipe for bottom end. After those two things if you still want more throttle response start going through the rest of the suggestions including pump tuning (impeller pitch/nozzle diameter) like I think stratton was getting at.



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  10. #10
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    Re: How to get more torque

    Okay so as far as cdi I️ have one out of a sit down I️ believe it’s not the good #3738.So if I️ change to the #3738 you guys think I️ll gains bottom end? But will I️ Sacrafice a lot of top? And a lot of you guys recommend high comp head first so I️ might do that and lighten my flywheel since I️ have a spare flywheel I️ can get I️t sent off during the summer just need to make sure I️ get my summer job. And how do I️ know if my factory pipe screws are working correctly is I️t just to make sure they turn freely or is there something else I️ need to do? Will I️ lose a lot of top end adding water? And also kind of a side question are the single carbs better at low end or is I️t duals? Appreciate the feedback from everyone has been very helpful.

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