Stihl 4mix fs100rx problem?

Discussion in 'Lawn Mowing' started by HenryB, Jul 21, 2007.

  1. HenryB

    HenryB LawnSite Bronze Member
    Messages: 1,844

    My worker says it will just cut off at full throttle sometimes. I ran it and could not get it to do this. However, I noticed it was surging (hunting) at idle. Any suggestions?
  2. carcrz

    carcrz LawnSite Silver Member
    Messages: 2,085

    Mine has also just started doing that. It takes a minute to warm up & then if it turn it on its side to edge, it will cut out one me until I turn it upright again.
  3. anj

    anj LawnSite Member
    Messages: 167

    I Had The Same Problem With My Fs100rx. They Replaced The Tank Valve. That Solved That Problem But Now The Sucker Runs Ruff As Heck. Just Vibrates Like Crazy When I Use It. I Put A New Head On It And It Still Does The Same Thing. My Other 100rx Runs Fine But This One Has Always Been A Problem. Anyone Have Any Ideas?
  4. MuleCutter

    MuleCutter LawnSite Member
    Messages: 212

    my idea is to get away from the 4-mix trimmers. after a month of owning my FS100rx the power decreased DRAMATICALLY and had to ditch it cuz of valve problems. i ended up getting a credit on it and with that money back i decided to try an echo 261T. had it 2 weeks and so far i love it other than how hot the clutch drum gets on my arm. i also put a stihl head on it cuz the echo head feels too sensitive. it throws string at the slightest bump.
  5. fiveoboy01

    fiveoboy01 LawnSite Silver Member
    Messages: 2,988

    After having my FS90R for around 2 months now, I concur with that statement.
  6. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,362

    I don't think the clutch drum gives off heat it should not slip unless you are not running full open....but the units do run hot and there is an add-on heat deflector they came out with.....for sensitive feed just stretch the spring if you want less feed out...
  7. HenryB

    HenryB LawnSite Bronze Member
    Messages: 1,844

    Update: Adjusted the valves today (1st tim, Cleaned air filter, new plug and de-carbanized exhaust port; It runs like new again. I really like this trimmer! :clapping:
  8. john_incircuit

    john_incircuit LawnSite Senior Member
    from NC
    Messages: 310

    How do you de-carbonize the exhaust port on the Stihl?
  9. Lawnworks

    Lawnworks LawnSite Fanatic
    from usa
    Messages: 5,407

    I love 4mix trimmers... they have been the only trimmer that has lasted longer than a year for my company. I have about 10 of them and some are going on three years. I would get one season out of redmax trimmers.
  10. sawman65

    sawman65 LawnSite Senior Member
    Messages: 754

    stihl offers a solvent for this and it needs to be done as regular maintance.
    the build up of carbon will not let the valve's close this = loss of power.the valves need to be adjusted after a few tanks of fuel are can be done as warranty. if you use cheap mix all these problems will happen.use stihl oil and you will have less of these problems

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