stihl bg-85 wont rev up.

Discussion in 'Mechanic and Repair' started by lawnwizards, Aug 29, 2009.

  1. lawnwizards

    lawnwizards LawnSite Silver Member
    Posts: 2,434

    i was using it last week when it completely died. i put in a new spark plug and it will start up but even at full throttle its only revving up to idle speed. could the gap in the spark plug being off cause this? or is this a carb issue? thanks.


    randy.
     
  2. Breezmeister

    Breezmeister LawnSite Bronze Member
    Male, from South Jersey
    Posts: 1,489

    I doubt it, but before you take the carb apart, here are a few things to check out.
    Do you have full travel of the throttle cable at the carb ?
    How does the fuel filter look, is it dirty ?
    Take the muffler off and check the exhaust port for carbon, clean it out if restricted. Remove the spark arrester on the muffler either way.
    Sorry, don't know alot about the 4mix set up, so you are on your own there
     
  3. lawnwizards

    lawnwizards LawnSite Silver Member
    Posts: 2,434

    i'll have to check the full travel. as far as the fuel filter, its o.k. the exhaust port is clean, didnt remove the spark arrester but it didnt look clogged. its just a 2 stroke and not a 4 mix.

    it has to do with the throttle not opening up all the way. i'll check it out first thing in the morning and get back with you. thanks
     
  4. hate2work

    hate2work LawnSite Member
    Posts: 91

    I've seen dozens of BG-85s that would not rev up, simply because the muffler screen was plugged. Use a deep socket ( 15 mm IIRC) and remove it from your muffler to check it. If dirty, use a wire brush to clean it and then put it back in, as some 2-cycles won't idle correctly without it in ( not enough back pressure ).
     
  5. Breezmeister

    Breezmeister LawnSite Bronze Member
    Male, from South Jersey
    Posts: 1,489

    If you don't have the full travel, check to see if the trigger assy or the grip has slipped/moved, this will cause the throttle cable to be out of alignment and fail to work. Of couse, you might just need a throttle cable .
     

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