FS 80 problems..suggestions?

Discussion in 'Lawn Mowing' started by happyjack, Jul 6, 2003.

  1. happyjack

    happyjack LawnSite Member
    from CT
    Messages: 3

    This is my 1st time posting on this forum, it's great.

    I purchased a FS 80 and have run 12 tanks of fuel through it. (Stihl mix and high Octane)

    The problem is When it's warm and run at full throttle there is a inconsistant popping sound coming from the exhaust. It sound almost like a skip.

    I brought it back to my dealer and he said it was fine. I doesn't sound fine to me. Any suggestions on how to fix this? Has anyone else run into this problem?

    I am a home owner and chose to buy a "commercial grade" trimmer so I would not have these problems. Plus the 2 yr warranty is nice.

    What should I do?

    Thanks in advance for your replies.

    SCAPEASAURUSREX LawnSite Senior Member
    Messages: 835

    Try calling Stihl 's technical dept , # should be in your paperwork or look up on the net.. Tell them whats happening and they should be able to advise... Sounds to me like it's getting too hot.. How long are you running it at full throttle... If your just doing trimming around the house and some edging, there is no need to run at full throttle.. half at the most....
  3. ElephantNest

    ElephantNest LawnSite Bronze Member
    from La.
    Messages: 1,878

    High octane? Why??
  4. LawnMower

    LawnMower LawnSite Senior Member
    Messages: 653

    I bet if you use the recommended 87 octane in her, she will run correctly. It wasnÂ’t meant to run on the high-octane gas.
  5. MTR

    MTR LawnSite Bronze Member
    from Florida
    Messages: 1,280

    using premium 93 octane is not good for a two cycle engine that small...I think you should try 87 grade with mix, I have been using my FS 85 rt and KM 85 R for over 6 months now and there is no chance of thing like what you said.
  6. bayfish

    bayfish LawnSite Senior Member
    Messages: 641

    Not the octane thing again! LOL
  7. mike48114

    mike48114 LawnSite Member
    Messages: 124

    Run the right octaine (87). The poping you hear might be the spark arrester in the muffler. Try cleaning it. If that dont work take it out. if that fixes your problem, your rocking! Make sure you put it back in before you take it in for service as removing it usally voids warantee.
  8. Grass Master

    Grass Master LawnSite Senior Member
    Messages: 328

    Read the owner's manual...

    Run 89 octane gas (as per the manual) and avoid alcohol in the gas..if you have too much alcohol in the gas the unit will run very hot!

    Also, ALWAYS run the unit at full throttle when possible...you are dealing with an air cooled engine that needs to run at full speed as much as possible...again look at the owner's manual.

    Good luck!
  9. happyjack

    happyjack LawnSite Member
    from CT
    Messages: 3

    Thanks I bunch guys I'll remove the screen and run 89 octane.

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