Js550/750 aluminum driveshaft
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  1. #1
    PWCToday Regular
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    Js550/750 aluminum driveshaft

    Curious if anybody has run these aluminum shafts you can buy off ebay with any gains or noticable throttle response. I got a dual carb 750 in my 440 with a 550 pump. The drive seems to vibrate a bit and was going to replace the shaft anyway.


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  2. #2
    PWCToday.com Is My Home Away From Home fastgtfairlane's Avatar
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    Re: Js550/750 aluminum driveshaft

    i would spend that money to have the stock driveshaft turned down and lightened before buying an aluminum shaft. problem with the aluminum shafts is the bend and twist really easily. besides with how small the diameter of the driveshaft, the rotating mass isnt actually much so being lighter doesnt make a lot of difference.
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    Last edited by fastgtfairlane; 03-04-2018 at 08:45 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

  3. #3
    Top Dog bandit88's Avatar
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    Re: Js550/750 aluminum driveshaft

    I would spend that money on a 750 pump conversion and a X2 driveshaft
    -95 750SXI
    -86 440 with PJS800 conversion - http://www.pwctoday.com/showthread.php?t=466927
    -90 TS650
    -91 300SX

  4. #4
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    Re: Js550/750 aluminum driveshaft

    Quote Originally Posted by bandit88 View Post
    I would spend that money on a 750 pump conversion and a X2 driveshaft
    What are the gain of this? Low end punch and top speed?


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  5. #5
    PWCToday.com Is My Home Away From Home fastgtfairlane's Avatar
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    Re: Js550/750 aluminum driveshaft

    Quote Originally Posted by bandit88 View Post
    I would spend that money on a 750 pump conversion and a X2 driveshaft
    couldnt agree more. i wouldnt do that unless i was going to bigger than 550ccs though. not worth it on a 550 engine. since the conversion kit came out x2 drive shafts prices have skyrocketed. the kit is 350 plus another 175 for the js conversion bushing and another 1-200 bucks for the pump. that quickly turns into 7-800 bucks especially if you have to buy a good impeller. more money than the ski is worth haha
    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

  6. #6
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    Re: Js550/750 aluminum driveshaft

    Quote Originally Posted by fastgtfairlane View Post
    couldnt agree more. i wouldnt do that unless i was going to bigger than 550ccs though. not worth it on a 550 engine. since the conversion kit came out x2 drive shafts prices have skyrocketed. the kit is 350 plus another 175 for the js conversion bushing and another 1-200 bucks for the pump. that quickly turns into 7-800 bucks especially if you have to buy a good impeller. more money than the ski is worth haha
    Whats the gain? A lot or just a little?


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  7. #7
    PWCToday.com Is My Home Away From Home BLRider's Avatar
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    Re: Js550/750 aluminum driveshaft

    Quote Originally Posted by jdrmx View Post
    Whats the gain? A lot or just a little?
    A lot.

    It's basically a 750 engine and driveline in a ski that weighs 50lbs less.
    Last edited by BLRider; 03-04-2018 at 09:39 PM.
    Never argue with an idiot, they will drag you down to their level then beat you with experience.

  8. #8
    Top Dog bandit88's Avatar
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    Re: Js550/750 aluminum driveshaft

    More bottom end, more top end, better hookup and rough water performance. Also, since it uses a floating bulkhead bearing, there will typically be less vibration if you install it right. Also no need to shim the driveshaft or motor. I would never consider running a 750 with a 440 or 550 pump
    -95 750SXI
    -86 440 with PJS800 conversion - http://www.pwctoday.com/showthread.php?t=466927
    -90 TS650
    -91 300SX

  9. #9
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    Re: Js550/750 aluminum driveshaft

    Sounds good


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  10. #10
    PWCToday.com Is My Home Away From Home theVetteman3's Avatar
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    Re: Js550/750 aluminum driveshaft

    I have a ton of info about the pump swap performance difference on my angry cardinal / pretty red build thread, in the individual builds section.

    That vibration is from bad alignment between either the engine and driveshaft, or driveshaft and pump. Each piece has it's own bearing set with it's own defined centerline making alignment really difficult. If you do anything with a stock pump, swapping everything over to 550sx parts, and going to a Rhaas bulkhead adapter would be a worthwhile upgrade. The bulkhead bearing mount floats allowing much easier aligning of the engine to driveshaft to pump.

    All that said, I switched to the 750 pump and never looked back. Depending on the hull, it can be quite a bit of work to eliminate all vibration, but once you do it's a huge improvement. But of course if you do that you definitely should have a 750 engine as well.
    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]
    1998 SXI PRO:
    3DR hull mods [TBD]



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