Stihl FS85 trimmer question

Discussion in 'Lawn Mowing' started by Roger, Apr 19, 2005.

  1. Roger

    Roger LawnSite Fanatic
    Posts: 5,927

    I have a question about idle speed control on 'start' mode on my trimmer. The throttle isn't in any different position than in 'run' mode, so I'm not getting any additional throttle during starting.

    I have had my trimmer for 4-5 seasons, working solo, trimming out about 1,100 lawns per season. Last season, perhaps in May, I changed out the braided wire throttle control, running from the trigger to the carburetor. It worked fine for the rest of the season. During the off-season, I cleaned up the motor unit, not making any adjustments. This Spring, I'm not getting proper throttle during 'start' mode.

    I do not see any adjustment on the cable between the trigger catch mechanism and the carb. The braided wire has an attached ball that catches on a screw head, providing the force from the trigger to the carb lever. The wire continues beyond the screw head to a bolt on the starter, providing a ground.

    The engine speed is identical between the 'run' mode and the 'start' mode. This means I'm starting the engine at idle speed, which doesn't work very well. I'm having to manually hold the trigger while starting so that the engine has some throttle beyond idle.

    I've scoured the manual and I find no information. I see a Torx screw head from the top, but I find nothing in the manual about an adjustment for this screw. I've tried screwing it a half turn one way, then the other, but no difference. I have returned it to the original setting.

    When running, the engine runs great, good power, just as normal, and just as I would expect.

    I have an FC85 edger with exactly the same power head. I've set them side by side to compare, but see nothing different. However, when I have the trigger in 'start' mode, I see a small movement on the carb lever, unlike the trimmer.

    Anybody have this problem? If so, what is the fix?

    Thanks.

    P.S. Don't suggest the dealer -- they've done more damage to my gear than I would bother to share here.
     
  2. dvmcmrhp52

    dvmcmrhp52 LawnSite Platinum Member
    from Pa.
    Posts: 4,205

    I'm not quite sure what your trying to say here but.............
    There is a half round cable guide that the throttle cable goes around on its way to the carburetor, it is adjustable for cable stretch and changing the cable, maybe you just need to re adjust it for a tighter fit on the cable.
     
  3. Spirit Lanwcare

    Spirit Lanwcare LawnSite Member
    Posts: 86

    Find a new (better) dealer and buy a new trimmer!
     
  4. Roger

    Roger LawnSite Fanatic
    Posts: 5,927

    dvmcmrhp52,
    Your post was enough for me to believe the Torx screw I spoke of in my question was to adjust the cable. When I turned it yesterday, I was not sure, so only turned it half-turn one way, then the other. This morning I turned it further. At three turns, some difference was noted. I turned it four, and it was better. A couple of more uses, I ended up at 4 1/2 turns, and have the 'start' speed where I want it. Thank you for your input.

    When I replaced the cable last season, the adjustment was apparently right for both the old cable and the new one. The speed was fine, but usage has apparently stretched the new one a very short distance.

    spirit -- I'm not yet flush with cash to throw away my equipment and buy new. I still need to make minor repairs and ajustments so that I can continue to use my old equipment. Maybe after this year, I'll be rolling in cash, so that I can use the throw away/buy new approach.
     

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