Stihl Chainsaw popping chain off HELP PLEASE

Discussion in 'Lawn Mowing' started by mikewhit1010, Jan 20, 2010.

  1. mikewhit1010

    mikewhit1010 LawnSite Senior Member
    Posts: 394

    I have never had Stihl Chainsaws pop chains off as much as my current one in the past two weeks. At first I thought it was my guys messing something up but our other saws work fine when they use them. I replaced the bar and the chain and still nothing.

    I heard that it could be the clutch? Any help would be appreciated.
  2. topsites

    topsites LawnSite Fanatic
    Posts: 21,653

    I am assuming you know how to adjust the chain's tightness?

    I would take it all apart and clean everything out real good, make sure it's got bar oil in the reservoir
    and put it all back together, adjust everything just perfect and of course inspect as you go.

    You might take a digital picture of it JUST before you put that cover back on as well, that might help us LS'ers.

    Then do a lengthy dry run, by dry run I mean don't cut anything with it, just run it while
    holding it to various rpm's and don't get your face too close but see what happens.
    Like for instance run it at really low rpm to where the chain is just turning and watch it for some time,
    see how it's going and all of that, I am pretty sure there has got to be some silly issue someplace that's
    causing it, maybe it's a piece of dirt caught in there or...

    What's happened to me before is that chain tightening mechanism wasn't in there right,
    I'd tighten up the chain just right and wouldn't think nothing of it but it would work itself loose...
    Or maybe the cover that holds everything in place broke one of those plastic pegs, who knows...
    Again why I would dry run it (and again by dry run I don't mean without oil lol).

    Good luck!
    Last edited: Jan 20, 2010
  3. mikewhit1010

    mikewhit1010 LawnSite Senior Member
    Posts: 394

    Thank you for the quick response. I will start to take it apart if no one else has any better ideas. Thanks TopSites
  4. meicher806

    meicher806 LawnSite Senior Member
    Posts: 385

    what saw is it?
  5. AOD

    AOD LawnSite Senior Member
    Posts: 331

    Is the bar bent? How is the bar groove and bar rails?

    Also, check the drivers, often times if you throw a chain the driver teeth catch on the bar and get bent, or if the chain has been pinched really bad the drive links themselves can be bent. This is especially true with Picco chains and other chains smaller then 3/8"

    Try another chain and see if it helps. If it does the same thing to multiple chains, try a different bar.
  6. mikewhit1010

    mikewhit1010 LawnSite Senior Member
    Posts: 394

    It is a Stihl MS 210 16inch.
    The bar and chain are both stihl and both brand new. Where the actual sprocket that spends the chain attached to the actual chainsaw is a little worn.
  7. Scagguy

    Scagguy LawnSite Bronze Member
    Posts: 1,522

    If the sprocket on the clutch is worn, it will cause problems. Replacing it will probably cure the issue.
  8. Turf Dawg

    Turf Dawg LawnSite Gold Member
    Posts: 3,719

    I will agree that the sprocket is generally what causes chains to jump off. I bet if you llok at yours, you will see deep grooves in it.
  9. Cutting hedges or a few small saplings at once will often cause the chain to come off the bar. Does it ever throw the chain when you are cutting solid pieces of wood that are over 2 inches thick? I've never had a saw throw a chain on solid pieces of wood, only when cutting small stuff.
  10. Oldtimer

    Oldtimer LawnSite Bronze Member
    Posts: 1,458

    Feel the drive links and if they are not smooth then replace the chain and sprocket. When the chain jumps off the drive links take a beating.

    Buy a drive sprocket and 2 new chains. When you install a new chain on a worn sprocket the chain instantly stretches so by rotating 2 chains they will all wear evenly. A new bar should be installed when replacing the chains and sprocket.

    When adjusting the chain hold up on the end of the bar.

    When tightening the bar nuts hold up on the end of the bar.

    If you don't hold up on the end of the bar the chain will still get some slack as soon as you begin to cut.

    Always break in a new chain by starting the saw and runing it just fast enough for the chain to move slowly. Do this for 3 or 4 minutes. Remember, the teeth travel @ about 50mph under full throttle so in a couple of hours a tooth could travel 100 miles.

    Never rev the saw or cut until the chain is broken in. This will give you the maximum life from the bar, chain and sprocket. Treat it like a new chain on an old Harley.

    After breaking in the chain let the unit cool for several minutes then adjust the chain because it will have stretched a little bit.

    There is absolutely no reason to keep pulling the trigger and reving the saw up and down. The only thing that does is make noise and more money for
    the dealers.

    Last edited: Jan 21, 2010

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