I may have answer for Stihl FS-55 problems

Discussion in 'Lawn Mowing' started by Tim Louis, Aug 5, 2005.

  1. Tim Louis

    Tim Louis LawnSite Member
    Posts: 41

    I've recently been having problems with my Stihl FS-55 weedeater. First it has been getting harder to start the last couple of months and it is a new plug. Then recently it will start but will not rev, it would just barely idle, and sounded horrible. I'm not that mechanically inclined so I figured it had gotten out of adjustment on the mixture screws. I played with all of them until they were practically stripped out and no luck, followed the manuals proceedures to adjust and everything and I knew it wasn't the air filter because I removed it and it didn't get any better. Well as I said I'm not that mechanically inclined so I was ready to take it to the dealer and have to use my piece of crap backup weedeater, but I figured I would take it to a friend who is very mechanically inclined and seems to know how to fix everything. Well I started it for him and after a couple of seconds it died and he told me that it sounded to him like the exhaust was plugged. My first thought was yea right, its only two years old, but from past experiences with him working on equipment I knew that he was able to fix just about anything so I didn't have a problem with him tearing into it, heck it was going to have to go to the dealer anyway so what did I have to lose. Well the first thing he did was pull out the muffler and then unscrew the exhaust port and wow that son of a gun was plugged solid with carbon. For those of you who dont know there is a mesh screen on the exhaust port for what reason I'm not sure but mine is not there no more. He put her back together and she runs like new, starts the first pull and revs and idles nice. I figure this is why Stihl reccommends that you operate your weedeater at full throttle so this wont happen, because I am the type of person to operate at 50% or less throttle for the majority of the time to cut down on damage to saplings, trees, and to throw less rocks, pebbles and other debris. It should be noted that we took apart a Stihl brushcutter that was older than mine and used much more frequently than mine and checked the exhaust screen and it did not have one speck of carbon on it probably because they are constantly run a full throttle. Hope this saves a couple of you a trip to the dealer.
     
  2. Myownyard

    Myownyard LawnSite Member
    Posts: 1

    After several ineffective "fixes" on my Stihl KM 55R (New Carb, new spark plug, blowing out the fuel lines and the fuel filter), all to no avail, I ran across this post which was good since I was about ready to smash the damned thing against the wall. I backed out the flame arrester screen fitting (yes, that's why it's there) and found it completely clogged with carbon. I looked for ways to remove the carbon on the internet but nothing really looked satisfactory. I happen to have a glass bead blasting box so, after first washing the screen assembly with brake parts cleaner to remove all oil, covering up the brass fitting with masking tape, I glass beaded the screen and it was clean as new within 10 seconds. I blew off/out the glass beads and dust, reinstalled the screen assembly on the Stihl engine, fired it up and the problem was gone. Engine runs like a top! Thanks! Bill

     
  3. Ridin' Green

    Ridin' Green LawnSite Fanatic
    Male, from Michigan
    Posts: 14,494

    If you run full synthetic oil like Stihl HP Ultra, or better yet, Amsoil Saber Pro, you will find that you never have to clean an exhaust screen or port again as long as you use decent fuel. I run Saber at 80:1 even thought it is made specifically for 100:1 use. I haven't cleaned the screen or ports in years and everything runs great and I don't smell near as much like smoke as I used to.
     
  4. HeadScratcher

    HeadScratcher LawnSite Senior Member
    Posts: 280

    So I guess those are even better than Opti-2?
     
  5. Ridin' Green

    Ridin' Green LawnSite Fanatic
    Male, from Michigan
    Posts: 14,494

    I can't say for sure better, but I can say with certainty every bit as good, and Saber is a lot less money than Opti 2
     
  6. southerntide

    southerntide LawnSite Fanatic
    Male, from Alabama
    Posts: 6,013

    I get carbon build up on my FS70R man I run HP Ultra too and the mix is dead on 1 bottle to 1gal exactly every time. Just chunked my spark arrestor screen the other day was so bad gotta pick one up, I couldn't get old one to go back in the edges frayed when I removed it.

    Ran it without it off and omg it's like a small dirt bike engine lmao

    edit - I also shake my can every time I refuel to make sure no mix it settling at bottom
     
    ericg likes this.
  7. Ridin' Green

    Ridin' Green LawnSite Fanatic
    Male, from Michigan
    Posts: 14,494

    I have never had that problem one time since switching to Saber, and you won't either if you run at 80:1 or higher. The ports and screens are as good as new whenever I check them.
     
    southerntide likes this.
  8. southerntide

    southerntide LawnSite Fanatic
    Male, from Alabama
    Posts: 6,013

    never even seen that mix here
     
    ericg likes this.
  9. Ridin' Green

    Ridin' Green LawnSite Fanatic
    Male, from Michigan
    Posts: 14,494

    You just have to do a search for a dealer on their site, and/or check some local auto parts stores. That's where I get mine. It id half the cost of HP and goes twice as far.
     
  10. a937539

    a937539 LawnSite Member
    Posts: 82

    To remove the carbon on the screen, you can take a propane torch and burn the screen. The heat from the torch will remove the carbon from the mesh.
     
    JDZ60 likes this.

Share This Page