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  1. #1
    2KPros's Avatar
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    Pro 785 Pistons & Connecting Rods

    Since the OEM versions of these are NLA from Polaris, I've been researching what's available from the aftermarket and this is what I've found:

    Pistons:

    WSM Cast SL 750 '93-'95 010-830K
    These work and are probably the best choice. I contacted them and there are no plans to discontinue these so that's good news.

    SBT Cast SL 750 '93-'95 47-303
    Should also work? Opinions?

    Wiseco Forged Pro 785 '97-'01 722M06970
    Forged are OK if you don't mind warming up the ski for a while

    I emailed Wossner and I'm waiting to hear if they make anything that works. If they do make pistons, then they're probably forged not cast.


    Connecting rods:

    SBT Pro 785 '97-'01 23-304-106 & 106A
    These are the only thing available that I can find. I also contacted them and there are no plans to discontinue these either. Awesome news!

    WSM claims they have rods but they say they fit a bunch of engines with 65mm strokes so these can't possibly work. I called them and the person I spoke to agreed and said he'd fix the website but so far it's not fixed.


    Can anyone list any other compatible pistons or connecting rods? And I'd also like to hear opinions on aftermarket crank oil seals and engine gaskets. There are a bunch of brands and I have no idea what's good and what's junk.

    Thanks guys.


  2. #2
    2KPros's Avatar
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    And Lugs, sorry for stealing your username. At the time I signed up on Greenhulk I didn't know that you already had that taken, and I can't change my username now!

  3. #3
    2KPros's Avatar
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    Wossner just replied, and they make a forged piston for the 785, 6024DA. They said that the pistons for the 750 have a shorter compression distance, which would lower the compression. So is that also the case when substituting other brand 750 pistons? I know people on this forum have said that they've used the WSM 750s with good results.

  4. #4

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    the wsm,sbt are the same as a 785 there where some snowmobile 750 pistons that where a bit different but all the watercraft
    will work

  5. #5

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    if you look at the wiseco pistons the 750 and 785 are the same part #

  6. #6
    2KPros's Avatar
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    Quote Originally Posted by 785 lugs View Post
    if you look at the wiseco pistons the 750 and 785 are the same part #
    I respectfully disagree. You are clearly one of the most knowledgeable 785 experts (if not the most!), but...
    When I look up the Wiseco pistons I get 2 different kits:

    Pro 785:
    http://www.wiseco.com/ProductDetail....00&AppID=22985

    SL 750:
    http://www.wiseco.com/ProductDetail....995&AppID=5526

    The rings, pin, and clips are the same part # though.

    Plus, why does Polaris have a different part # for the pistons?:

    Pro 785 = 3240329
    SL 750 = 3240146

    Not saying that the SL 750s don't work, because they obviously do, but I wonder what the differences are, and how it affects performance.
    I think Sloan said they are lighter and allow the engine to rev faster?

    Have you ever tried the SBT cast SL 750s that I referenced in my 1st post? They look like nice pistons. Or is the graphite on the sides a bad idea with the Pro's nikasil plating?

  7. #7
    2KPros's Avatar
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    Here's the link:

    http://www.shopsbt.com/jetski/Polari...-1995-pwc.html

    And what's your opinion on running forged pistons?

    I tried to investigate why forged pistions require more clearance than cast, and I found this interesting link:

    http://forums.nasioc.com/forums/show....php?t=1061799

    It's about forged vs cast in 4-stroke car engines, but the topic applies to 2-strokes too.

  8. #8

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    Like so many 785 owners, you are overthinking. Use the SBT rods, and WSM 750 pistons. Build the motor as per factory manual. Unless you are racing superstock class, this combo will work for rec riding. If you like to spend money and rebulid motors, than use forged pistons, the motor MUST be at operating temp before full throttle. Unless you are racing in the world finals forget about them.
    There has been a rash of guys lately trying to rengineer the Pro 785, build as per factory manual, listen to Bob, and enjoy it. Polaris and Fuji did all the hard work for you.

  9. #9
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    Sloan's right over thought , the 750 has a different part number because the bores are not the same 750 has a bore of 69.75 and a 785 is 69.70 and yes they work fine

  10. #10
    2KPros's Avatar
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    Quote Originally Posted by 785 View Post
    I respectfully disagree. You are clearly one of the most knowledgeable 785 experts (if not the most!), but...
    When I look up the Wiseco pistons I get 2 different kits:

    Pro 785:
    http://www.wiseco.com/ProductDetail....00&AppID=22985

    SL 750:
    http://www.wiseco.com/ProductDetail....995&AppID=5526

    The rings, pin, and clips are the same part # though.

    Plus, why does Polaris have a different part # for the pistons?:

    Pro 785 = 3240329
    SL 750 = 3240146

    Not saying that the SL 750s don't work, because they obviously do, but I wonder what the differences are, and how it affects performance.
    I think Sloan said they are lighter and allow the engine to rev faster?

    Have you ever tried the SBT cast SL 750s that I referenced in my 1st post? They look like nice pistons. Or is the graphite on the sides a bad idea with the Pro's nikasil plating?
    Maybe Lugs is right. Both Wiseco kits say "ProLite 2746CD" so I guess the kits are exactly the same but they give them different part #s? That's kind of strange.

    Sorry, not trying to overthink. I just wanted to know what's the best substitute for the NLA stock pistons. Thanks for the advice.

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