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  1. #1

    going to bigger piston

    hello guys, i have a stock piston on my slx780 1995, since the 2 piston overheated and broke the pistons, im planning to bore the sleeve and go to the next larger piston...whats the next size??? and with this...what main jets should i be running???

    what is the limit clearance of the stock piston? when i will be honing my sleeves?
    Last edited by andy95'slx780; 02-12-2008 at 02:55 AM.


  2. #2
    ph2ocraft's Avatar
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    How damaged are the cylinders?
    Have you checked the taper bore?
    From years of use you should be wider or more worn at the bottom of the cylinder versus the top. You need to measure the maximum size you have now so you know what our next psiton size replacement will be.
    If the cylinder wall is scored you need to have your machinist figure out how large he needs to make the bore before the damaged cylinder is ready for use.
    If it's just going to be a quick hone, factory size over is .25 and .50mm over.
    Wiseco does .20 and .71mm over, I don't know about WSM.
    Until you figure how much you need to bore the cylinder and which piston you go with can you decide on finished boring size.

  3. #3
    Water Bum Rodneyae's Avatar
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    You can find the specs. here...

    http://www.wiseco.com/Catalogs/PersonalWatercraft.aspx

    Keep in mind if you go bigger you more than likely will have to rejet the carbs to keep up with the increased displacment.

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by andy95'slx780 View Post
    hello guys, i have a stock piston on my slx780 1995, since the 2 piston overheated and broke the pistons, im planning to bore the sleeve and go to the next larger piston...whats the next size??? and with this...what main jets should i be running???

    what is the limit clearance of the stock piston? when i will be honing my sleeves?
    Polaris 1992-1997 manual download page

    All the factory specs are there.

  5. #5
    thank you so much...

  6. #6
    Bing-A-Ding-Ding-Ding, Brrrrrap! Brrrrrrrrrap!!! Polaris_Nut#1's Avatar
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    My 96 SLX is 1.5mm over sized and had enough adjustment on the carb screws. The 95 has different jets because it had a different impeller but you should still have no problem dialing it in with the stock jets. If you are just replacing the pistons (even with a larger size ) you should be fine. If you modify your heads in anyway forget about what I just said.

  7. #7
    if my piston is stock, what is the next bigger size??

  8. #8
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Next size bigger is .25mm. BUT, if your cyl is damaged, you may need to go .5mm or even .75mm depending how badly damaged it is.

  9. #9
    ok.......its not that bad...i think ill go with the .25mm

  10. #10
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    How bad is the damage? .25mm means only half of that will be removed from one side of the cylinder, while the other side gets the other half removed. So, if you have a gouge that's deeper than half the .25mm oversized, you'll need to go bigger still. Does that make sense? Let the machine shop look into it for you please.

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