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  1. #1

    SL780 tuning problems

    Hi
    I have just rebuilt my SL780 and put boysen reeds in but it is running really rough down low and seems to be to rich. I have played with the lo speed screw but dosent seem to help much. It runs great at the top end. do i need to rejet the carbs or anything like that?


  2. #2
    have you ever run this ski before? some people freak when the first see a 2 stroke at idle what rpm's? did nyou go thru the carbs? check popoff etc?

  3. #3
    I have not had it running properly scince i got it. How do you check popoff? it is real sluggish un till you get to half throttle the it kicks into life. I think the guy i got it off was a fiddler Ive got a Clymer manual but i have set the carbs to there specs but it stinks of fuel down low.

  4. #4
    what did your rebuild consist of? Pop off will tell you if your needle and seats are working properly! leaky Needle and seats dump fuel int the motor! I will pm you some links Z

  5. #5
    rebuild conssited of pistons rings bearings and boysen reeds

  6. #6
    what should the popoff be?

  7. #7
    not sure on yours but I usually just make sure they are all close to the same and that they do indeed pop rather than bleed past a leaky needle
    I believe this is your issue

  8. #8
    you might find popoff value in this large pdf that Mattman hosted http://www.mattmans.com/polaris/uplo...viceManual.pdf

  9. #9
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Welcome to the Hulk Oriec. What year 780 do you have? Have you gone through the carbs at all? If the previous owner was a fiddler, maybe he changed the jetting. Do you have any other mods done to the ski?

  10. #10
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by oriec View Post
    what should the popoff be?
    Usually 38mm Mikuni SBN pop off is between 10-18 psi.

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