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FS 91 tuning

Discussion in 'Chainsaws and Power Equipment' started by NBourque, Jun 8, 2021.

  1. NBourque

    NBourque

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    Hey guys. I gotta FS 91 I bought 3 years ago. It has maybe 5-6 tanks run thru it. I’ve had it to the dealer once already two years ago for a bogging issue. Seemed fine up until today. Got halfway thru trimming and it just started to bog when I got on the throttle. Tried adjusting the carb to no avail. Any ideas? Prob gonna drop it off tomorrow at the dealer.
     
  2. buzz-saw

    buzz-saw

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    A bog is usually a fuel problem , lack of fuel.
    Try loosening the fuel cap to allow air into the tank and try it again , maybe a clogged tank vent.
    Open up the high side needle a little , a limiter cap might be on there to prevent you from opening it up ; get rid of that if you have one.
    Just a couple things to try quick.
     
  3. SAWMIKAZE

    SAWMIKAZE

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    My 91 had no limiter caps so I'm sure yours doesn't either. Just the hex carb tool is all it takes, same on my 131.

    That kind of problem within 5 or 6 tanks is definitely way off, it could be a few things...
     
  4. NBourque

    NBourque

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    Opened the fuel cap. Filled it with gas. Still no go.
     
  5. PA Mountain Man

    PA Mountain Man

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    Check the plastic lines and gaskets between the fuel tank and carb
     
  6. NBourque

    NBourque

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    Does stihl make a commercial trimmer with a regular 2 stroke or is their whole commercial line 4 mix? Haven’t been real impressed with the 4 mix...
     
  7. Canadian border VT

    Canadian border VT

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    Yes just got a split shaft 2 stroke power head last month as I have chain saw, tiller and other attachments
     
  8. NBourque

    NBourque

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    What’s the model?
     
  9. Canadian border VT

    Canadian border VT

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    0D3B64E7-0908-4BE7-9B68-F2776A2C6ECC.jpeg

    Comes in 3 sizes. 91 110. 131. I got biggest because rototiller for just string trimmer too much power.

    saw blade attachment will drop 3” maple saplings
     
  10. NBourque

    NBourque

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    The dealer ended up adjusting the carb. Runs awesome now. Guess I have no idea how to adjust the carb on a 4 mix lol.
     
    PA Mountain Man and Chud like this.