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  1. #1

    96 sl780 backfires...need help

    i got a 96 polaris sl780. it ran great a week ago and i had no problems and my buddy thaught he could tune it in a little better and he completely set the highs and lows wrong. he didnt remember where they were at in the beginning. i looked all over and got the stock carb setting and set them there but it has no power. it says 5/8 out on the lows and 3/4mag,3/4c,and1p. it has a good idle no matter were the low is set at. as soon as you give it full throttle it has nothing there. then you let of and it goes back to a normal idle. so i turned the highs out a little bit and now it still has a good idle but if you give it full throttle it back fires. can anyone help me or give me the exact settings to where they have there carbs set at so i can try that. i have tried to get it tuned back in for 3 days straight and it doesnt get any better.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome

    Did your buddy or you change anything other than the carb screws?

    Was the machine rolled over recently or got water inside the hull, or run on the hose with the engine off, and the water on?

  3. #3
    la90043's Avatar
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    look on the cooling rail of the engine. right on top of the pistons. there's a decal there. it indicates the engine number.

    WHATS THE NUMBER?

    MAYBE YOU HAVE THE INCORRECT CARB SETTINGS.

  4. #4
    he hasnt changed anything. just set the screws in the wrong place. the engine number is ec780p e0213185. in between the space there is a symbol that has a circle around it. the last digits in the vin number is 96. the ski pulled peak rpm's before and ran prolly 55mph. he just thaught he could tune it in a little better i guess. big mistake because i cant tune this thing in and no shop around here wants to work on it.

  5. #5
    la90043's Avatar
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    Looks like the right settings.

    Seems like you have the low speed adjuster screws set wrong. Check them. Start 5/8 turn out from a litely seated position.

    Screw it in. Then back it out to 5/8. if it still goes no where. Then give it just a tad more. 1/16 more. Its has to go.

    If not. There's something else wrong with it.



    Quote Originally Posted by ryankinder82 View Post
    he hasnt changed anything. just set the screws in the wrong place. the engine number is ec780p e0213185. in between the space there is a symbol that has a circle around it. the last digits in the vin number is 96. the ski pulled peak rpm's before and ran prolly 55mph. he just thaught he could tune it in a little better i guess. big mistake because i cant tune this thing in and no shop around here wants to work on it.

  6. #6
    so how do you think i should adjust the high speed screws. should they stay at the stock settings. im getting ready to take it down to the river. im going to set everything at the stock settings and then back the lows out 1/16 like you said and see what it does. i just want to know what you think i should set the high at.

  7. #7
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Welcome to the Hulk.

    Start the highs at stock, or just a tad more OUT. (richer)

    Were there any mods done to the ski?

  8. #8
    seaobin's Avatar
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    He needs to start from scratch.

    Closes high speed circuits and adjust lows on short hops. Once lows are set, then set highs to stock and follow the procedures in the forum.

    Just adjusting 1 cylinder (H and L) at a time and messing around will take forever

  9. #9
    ok so ill close the high speed screws all the way. what am i tuning for by turning just the lows speeds. am i just checking the plugs and wash for the correct mixture. or am i adjusting the lows for take off.

  10. #10
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Adjsuting lows for smooth idle and take off.

    Short bursts of 50 ft or less.

    check this out. http://greenhulk.net/forums/showthre...t=15473&page=2

    Post 13 explains what to do.

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