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Thread: Tuning Issue

  1. #1

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    Tuning Issue

    Hi All,

    I've got my SLX780 running quite nicely, but think there is an issue with the carbies. I've had 90% of the engine apart during it's post purchase rebuild (1 piston replaced), but did not strip down the carbies as the had only been rebulit by the previous owner.

    One cylinder (piston wash) is now showing good tune, but the other two are still quite rich even though the top end mixture needle is in much further in than the manual states. Should I just keep leaning them out, or could the pop off setting be so far out that it won't matter how far I lean the needle?


  2. #2
    ryandi2's Avatar
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    you should post this in the discussion area.. you wont get many hits here.. this is a place too look up info

  3. #3
    thester71's Avatar
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    I would go through the carbs completely, paying special attention to the mixture screws making sure they are not damaged at the tip. You could always go down a size on the main jets if you have to. I'm pretty sure pop off has little affect on the high speed circuit.

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

    Definately go through the carbs. Check to make sure the PO used the correct jet sizes, correct needles and seats, and has the correct pop off pressure.

    As mentioned above ^^^^ check the mixture screws for damage.

    It's also possible the PO installed a different impeller or CDI. Either of those can change jetting.

    Won't cost you a thing to check any of them. (maybe carb base gaskets, but you can make your own for cheap) And at least you'll know exactly what it is you have.

  5. #5
    thester71's Avatar
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    Actually I have heard of people forgetting to INSTALL the jet completely

  6. #6
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by thester71 View Post
    Actually I have heard of people forgetting to INSTALL the jet completely
    Yeah!!!!!

    Me too....

  7. #7
    bowsniper's Avatar
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    I had a 100hp engine that the mixture needles vibrated right out! Hello fuel!..why is it sputtering? Duh....


    Sounds like a Carb Cleaning inspection is in order. 3-cylinders are really fussy. they have to be super clean,air leak free operation, and then they will run great!. 1 carb is all it takes...


    If you can get a hold of a used bigscreen tv,, open up the back of it and take out one of the HUGE lens's in there from the electron gun. They are like 4 inches across and make awesome up close inspection tools for reading the jets and checking needles for wear n tear. !.

  8. #8
    SPEED KILLS, BUT YOU GET THERE QUICKER Keddano's Avatar
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    Quote Originally Posted by bowsniper View Post


    If you can get a hold of a used bigscreen tv,, open up the back of it and take out one of the HUGE lens's in there from the electron gun. They are like 4 inches across and make awesome up close inspection tools for reading the jets and checking needles for wear n tear. !.
    Bow,You have too much time on your hands,I think you need a hobby....like maybe buy a jet ski or two....

  9. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by Keddano View Post
    Bow, You have too much time on your hands, I think you need a hobby....like maybe buy a jet ski or two....
    bowsniper: Posts Per Day: 3.22

    Doesn't seem accurate, does it?

  10. #10

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    Okay well I've taken your advice, stripped the carbies (after not being able to get a good wash pattern, even down to 1/4 turn out) & found that the main jets are 112 and the manual states 105. Is that a big difference in jet terms?

    Bottom-end jets are as stated in the manual 72.5.

    Also found that all of the top-end needles are quite badly stepped, so I'll try to get new needles as well.

    Edit: Forgot to say that it's got a 13x18 SkatTrak, and the rest is pretty well stock. Will the 105's be right?

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