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  1. #1

    Polaris SLT 780 performance upgrades?

    Thanks to everyone’s help here on the Hulk I've been able to successfully take on a "father and son" project rebuilding to factory spec performance our 97 SLT 780's. These machines are a lot of fun and we've had a great summer on the water with them.

    Again, thanks to everyone here for all the help getting these machines up and running.

    Now, I know just enough about these engines/machines to be dangerous lol

    So now, I'm working on my 3rd SLT 780 project and I'm looking to make this third one "special".

    Having rebuilt two already, I was wondering if anyone out there might like to live vicariously through me and help with suggestions on how I might take this third stock 96 Polaris (Blue Fuji) SLT 780 to its performance limits. I was thinking about dumping a 900 or 1050 into the hull but figured while I have this engine that I would'nt mind experimenting with it first.

    I'm looking for ways I might improve the performance through any means. Props to plugs, pistons to carbs.


    Are there any upgrades I can take advantage of? Any customizations? Carb or exhaust upgrades?

    Maybe start by over sizing pistons? Splitting head gaskets? Shaving the heads? etc..

    I don't mind experimenting. I don’t mind failure. (at least initially)


    Any suggestions or links to other threads would be greatly appreciated. Simple things first and build on success

    Bobby


  2. #2
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    I would start by changing the ride plate. The OP plates are worth about 2 MPH. I have added trim to both of my SLT hulls, and I love what it does for them. A 6 degree pump wedge as opposed to the stock 4 degree will give a little more speed as well. Stock prop is a good choice, make sure every part of the pump, from stator vanes to impeller blades and clearances are perfect. 6 vane stainless stator is a good upgrade. All of those things might get you 3-4 MPH by itself. I like what the Boyesen Pro Series reeds did for my fuji motors. All of those addons should get you 52-54 MPH on GPS with that ski.

  3. #3
    Quote Originally Posted by BryanP View Post
    I would start by changing the ride plate. The OP plates are worth about 2 MPH. I have added trim to both of my SLT hulls, and I love what it does for them. A 6 degree pump wedge as opposed to the stock 4 degree will give a little more speed as well. Stock prop is a good choice, make sure every part of the pump, from stator vanes to impeller blades and clearances are perfect. 6 vane stainless stator is a good upgrade. All of those things might get you 3-4 MPH by itself. I like what the Boyesen Pro Series reeds did for my fuji motors. All of those addons should get you 52-54 MPH on GPS with that ski.
    Perfect,Thanks for the info... OP plates, Boyesen Pro Series reeds... who might a good source for those?

  4. #4
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    Op plate you can get direct from Ocean pro

  5. #5
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Performance reeds are good, and having your stock heads cut for 92 octane fuel would also be good.

    Oversize pistons don't really add all that much.


    There are a couple guys that have done some mods to the 780 and swears it runs really hard. Sea Lion was the first to mention it, and Tech SLX followed the same set up and really liked it to.

    44mm carbs, Pro 785 CDI, 92 650 dry exhaust pipe, and a 12/17 impeller with a 3mm bored venturi. (87mm)


    http://www.greenhulk.net/forums/showthread.php?t=73459

  6. #6
    burtonrider10022's Avatar
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    OP, I know of a great price on some brand new Boysen Performance Reeds, but they're not the PRO model. If someone chimes in here and says that those are still worthwhile PM me.

    Also, everything I've read says that an Adjust-A-Thrust is a really great mod and it's got amazing "bang for your buck" @ ~$150 new.

  7. #7
    Quote Originally Posted by BryanP View Post
    Op plate you can get direct from Ocean pro
    Perfect thanks!

  8. #8
    Quote Originally Posted by xlint89 View Post
    Performance reeds are good, and having your stock heads cut for 92 octane fuel would also be good.

    Oversize pistons don't really add all that much.


    There are a couple guys that have done some mods to the 780 and swears it runs really hard. Sea Lion was the first to mention it, and Tech SLX followed the same set up and really liked it to.

    44mm carbs, Pro 785 CDI, 92 650 dry exhaust pipe, and a 12/17 impeller with a 3mm bored venturi. (87mm)


    http://www.greenhulk.net/forums/showthread.php?t=73459
    I'm gonna have fun with this...thanks for the link

  9. #9
    Quote Originally Posted by burtonrider10022 View Post
    OP, I know of a great price on some brand new Boysen Performance Reeds, but they're not the PRO model. If someone chimes in here and says that those are still worthwhile PM me.

    Also, everything I've read says that an Adjust-A-Thrust is a really great mod and it's got amazing "bang for your buck" @ ~$150 new.
    I'll give it a shot and let you know how it works out. I'm going to document the incremental progress' along the way using GPS

  10. #10
    Sooo...how much for the 780? stimpsonjcat's Avatar
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    Interesting.

    So the adjust-a-thrust is essentially a modified tailcone that allows you to extend the cone to take up more volume in the pump. I might have to take a stab at fabricating something similar.

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