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Help to adjustment carburetor on Stihl 031AV

Discussion in 'Chainsaw' started by JamesReed, Jan 21, 2006.

  1. JamesReed

    JamesReed ArboristSite Member

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    Need some help for those who know how to adjust the carb on this older model - Stihl 031 AV. I just rebuilt and have no manual to help with adjusting. It is a Walbro with a H and L plus an needle that one can adjust inward to open/adjust the throttle in more.

    Here is what I do: First - Screw H and L all the way in and back-off both H&L 1 full turn. Start saw. Chain is really moving fast/oil coming out on bar. I slowly turn to the right the L (one next to combustion chamber) until the chain is almost stopped or barely moving. Next I trigger saw to test high speed. Saw bogs down when I try to rev saw up to check high speed and usually stalls out. :bang:

    When and do I use the screw-in needle adjustment that can hold throttle open?.:confused:

    Thanks
     
  2. t_andersen

    t_andersen ArboristSite Operative

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  3. WadePatton

    WadePatton AboristSite Guru

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    Now that's the ticket.

    What do you do when step #4 doesn't work--can't warm saw up 'cause saw won't run?:bang:

    It'll run here and there, but 30-40 seconds has been tops. Maybe 10 seconds otherwise. The rest is stammer/no hit. Just had carb off, diaphram was on upside down--no fuel at all that way. Three pulls choked, then 2nd or third pull off choke and it'll stammer/putt-putt.
     
  4. Lakeside53

    Lakeside53 Stihl Wrenching

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    jamesreed : you're forgetting to first set the LA screw so the saw "just" idles with the L screw out one turn (or 1 1/4 depending on your carb).... then adjust the "L", (and maybe the LA again) then the "H".

    yes, look at the suggested Madsens link.
     
  5. Lakeside53

    Lakeside53 Stihl Wrenching

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    Just ignore the warm up... adjust it anyway you need to to idle, even if it means winding in the LA screw a lot before adjusting the L, then back off the LA etc... Then figure out what is wrong with your H, or maybe your impulse line?
     
  6. WadePatton

    WadePatton AboristSite Guru

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    So that's what it's called--impulse line.

    Now that I've become a master of the linkage, I'll go back in. I replaced the fuel line, hoping that was the deal. It ain't.
     

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