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  1. #1

    Polaris sl 750 upgrade

    I am wondering where I can find a piston upgrade. For a 1994 Polaris sl 750?! I have read some post on here about the upgrade but have been unsuccessful in finding one!


  2. #2
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    Whats wrong with your stock pistons?

  3. #3
    Quote Originally Posted by BryanP View Post
    Whats wrong with your stock pistons?
    Runs a little rough right now. Replaced all fuel lines, put on triple line fuel pump. Rebuilt carbs and new read valves!! A friend of mine told me about upgrading the heads to a 780. I was just wondering if I could get any info on it

  4. #4
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Welcome to the Hulk Chance.

    You're getting some bogus info from your "friend".

    There is no piston "upgrade". There are Wiseco pistons that are forged, and used to weigh less, but they were prone to seizing and most of us run stock or stock-like (cast type) pistons.

    And as far as the 780 heads on a 750, that would be a performance decrease. The 750 bore is 69.72mm and the 780 is 71.3mm. Both use the same 65mm stroke, so you'd be LOSING compression by installing a larger bore head.

    Do yourself a favor and stop listening to your "friend". He's going to have you wasting your $$$ on parts that won't make you go any faster.

    And did you use GENUINE Mikuni parts when you rebuilt your carbs?

  5. #5
    BlueFishCrisis's Avatar
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    It is possible the 780 reference was made regarding a complete top end swap out. If that is the case you would get improved performance, RPM, and top end speed, but you are talking about replacing all three jugs, pistons, rings, heads, carb jetting, etc.... Hundreds of dollars in parts, not a simple bolt on deal......

  6. #6
    ripcuda's Avatar
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    Welcome to Green Hulk!

    Have you done a compression test yet?
    What did you set your carb hi/low mixture screws at?
    Did you keep the fuel restrictor in the return fuel line?

    There is tons of info about your engine and ski... start here: http://polarispwcknowledge.shorturl.com/

    Good luck

  7. #7
    RLACEMAN's Avatar
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    I did the 750 to 780 conversion, only gained a couple mph on top end, but acceleration was greatly improved, cost me about $500-$600 to do, would I do it again, probably not. Unless your seized or burned down a cylinder no reason to replace a piston. If you ever do I don't recommend Wiseco's, they are about as reliable as putting a beer can in the cylinder.

  8. #8
    Quote Originally Posted by RLACEMAN View Post
    I did the 750 to 780 conversion, only gained a couple mph on top end, but acceleration was greatly improved, cost me about $500-$600 to do, would I do it again, probably not. Unless your seized or burned down a cylinder no reason to replace a piston. If you ever do I don't recommend Wiseco's, they are about as reliable as putting a beer can in the cylinder.
    I just got info off my mechanic, he said he didn't rebuild carbs! He just cleaned and replaced gaskets. I installed the triple valve fuel pump took it out today and it was very pour performance. Didn't have any power at all. I am having exhaust problems, there is a leak in the "hull" I'm new at the lingo. When I took the seat off to adjust the fuel screws it was full of smoke.. What should I check and replace?! We don't have any mechanic shops around paris that will work on them

  9. #9
    RLACEMAN's Avatar
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    If you took the seat of & have smoke in it, that is causing the poor peformance, check the exhaust hoses, its probably the one between the pipe & the muffler, but could be the big curved one coming out of the muffer, run it briefly on the trailer you should be able to see that easily.

  10. #10
    Quote Originally Posted by RLACEMAN View Post
    If you took the seat of & have smoke in it, that is causing the poor peformance, check the exhaust hoses, its probably the one between the pipe & the muffler, but could be the big curved one coming out of the muffer, run it briefly on the trailer you should be able to see that easily.
    Thanks for advice, I checked and found a leak! Took apart, cleaned and replaced bad part. Took it out today it ran great.

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