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  1. #1
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    sl 780 triple pipe question

    Can factory pro 785 pipes be easily installed in a 97 sl780? The exaust manifolds dont look as if they would bolt up, and if they would, how would the water flow through the water jackets at the exaust outlet?
    I just can't see it happening. I have also seen a picture of a 785 jug, and still dont see how they would fit it. i.e. round exaust port fitting a rectangular manifold flange.
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  2. #2
    Water Bum Rodneyae's Avatar
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    before attempting you need to read this thread....

    Triple 780 Transplant w/Triple pipes
    http://www.greenhulk.net/forums/showthread.php?t=17470

    I put a set of tripples in my SL hull. Not too hard but not easy either.

  3. #3
    Water Bum Rodneyae's Avatar
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    You would have to cut the square flange off and have a custom adapter built. It could be done. Not easy....

  4. #4
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Quote Originally Posted by Rodneyae View Post
    You would have to cut the square flange off and have a custom adapter built. It could be done. Not easy....

    I thought the 785 jug had a similar exaust outlet as the 650-780 jug. The pic I attached doesn't look as if it will fit any of them or the 785. In fact I'm thinking the the exaust mani in the pic may be for another make of ski. I'm just not sure.
    I read your posting of your project, and was thinking that the PSI pipes would have more fitment issues than Polaris factory pipes. Your setup was a tight fit, and I'm game for such a project, but isn't the pro 785 the same as a sl hull? I'm confident that if they will fit the pro hull, I can make them fit the sl780.
    Anyone have any pics of a pro785 w/ factory pipes? Especially of the manifold connection to the jug? I just can't see how water would flow through the manis in the pic, or how you would pipe the water jacket separate.

    Thanks for your reply Rodneyae.
    Last edited by starflight; 11-13-2007 at 09:44 PM.

  5. #5
    Moderator beerdart's Avatar
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    Those are 785 manifolds and only fit the pro. The pro pipes should fit the SL Hull. The Pro Hull has a different bottom and same top deck as the SL.
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  6. #6
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Thanks BD. I see that the pro manis are different than the 780. 3-4 bolt pattern. But the pic I have looks way different than yours. The flange in my pic is more narrow than yours, and no room for the water passages that I can see.
    Might there be an exaust mani adapter of sorts that will allow the use of the pro pipes on a 780?
    The guy that has a shop next to mine custom fabricates all sorts of stuff. From special effects helicopters for the movie studios to custom components for his APBA Cracker Box series boats that he and his brother developed decades ago. He has even helped develope stuff for Hallett.
    His latest creation is a carbon fiber hull for his series of race boat thats leading the pack this season. I'm sure he would help fabricate a manifold for me, but financial constraints may be a problem. I would rather find an easier solution to make the connection to the jug.
    Thanks guys!
    Last edited by starflight; 11-13-2007 at 10:35 PM.

  7. #7
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by starflight View Post
    ...Might there be an exaust mani adapter of sorts that will allow the use of the pro pipes on a 780?
    ...financial constraints may be a problem. I would rather find an easier solution to make the connection to the jug.
    Thanks guys!
    Perhaps you could sell your 780 motor, and buy a 785 motor to drop into your hull?

    Or would 785 jugs fit on your 780 bottom end?

    And the CDI to match, as needed.

  8. #8
    Water Bum Rodneyae's Avatar
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    You would also need to change the rods also. As the 785 has a longer storke.
    Quote Originally Posted by K447 View Post
    Perhaps you could sell your 780 motor, and buy a 785 motor to drop into your hull?

    Or would 785 jugs fit on your 780 bottom end?

    And the CDI to match, as needed.

  9. #9
    Water Bum Rodneyae's Avatar
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    You could drill and tap the pipes for nipples for the water coolant. Like the ones on my project.

  10. #10
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    I have the cdi, and its my understanding( may be wrong, have been guilty of that before) that the jugs would fit, but I would lose alot of CC's due to a smaller bore. The 785 makes up the CC's with a longer stroke, that I don't have.
    If I could find a complete engine for 5-6 hundy I'd jump all over it, but I can get the pipes for a decent price. Just need to find a way to get triple pipes in what I have now.
    I'm in need of a project for this winter, but our winter is rather short.

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