Stihl MS291 Strange Problem
- Thread starter Wood Doctor
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I'll do that, but at this point I am not optimistic, unless this can be fixed without buying a new top end. Stihl dealer said it was not worth the money, and he's right. New jug -- $200, new crankshaft $150, new seals -- $50, and the list goes on. I think it's a dead puppy.
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It looks like one could reseal, and drill a couple tiny holes that one could thread some screws and washers. Looks like enough meat there to do it.
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It wouldn't be pretty, but it should work.
I don't have one on hand to get a better look.
I don't have one on hand to get a better look.
SteveSr
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I suspect that the issue with the transfer covers coming off is that the cylinder gets too hot and softens up the adhesive. Next you have an air leak and a dead saw. Not a great design IMHO.
Agreed. I have never been a fan of the clam shell design. The ambient heat has also been high and that is when this saw failed. I also don't it think commercial use is in the cards for a Farm Boss. Tree service companies tend to beat them to death, and that's who was using this saw.
What holds the side covers on to start with ?
Good question. The side covers are not listed as a part in the IPL. So, they must be a integral part of the cylinder, whatever they are, likely welded into place to reinforce the casting. The cylinder casting may have been underdesigned in the first place, so the side covers were added as strengtheners. No side cover is shown here:
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You can see the gray sealant just above the crank.
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Here again.
Yes, Harley, that's the part that the IPL does not show. A sealant is between this part and the cylinder casting. Two of these may have been added after 2017 (the year the saw I have was made) in an effort to reinforce castings that were breaking under operatimg stress.
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Yours have the old style intake boot?
Perhaps. Not sure what that has to do with it. Did a new style intake boot show up after 2017? Regardless, the cylinder I have that may have given up does not have the side support strengtheners (flaps as you called them) that the above red arrow points to.
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Yeah, it was around then. The newer boot is round with a clamp.
Harley you have a new ms 260 piston and rings by any chance? I’ll have to get back to you re the exact size as from memory there is two.
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No, sorry. I haven't messed with the ms261 yet.
And I only sell the whole thing.
And I only sell the whole thing.
Right, but it's cheap to manufacture. Steve
Last 290 I worked on sounded like a cement mixer and when I got it apart the crank shaft was cracked near the rod. Had eaten up some of the castings where the counterweights were hitting due to the crank flexing and wobbling from the crack. Customer got a 390 sleeper out of the ordeal! 
Just got a call from the owner. He says forget this 291 and save it for parts. He may go shopping for a 391 instead. He has several saws this size for backup. New parts are too expensive to fix these puppies and it cannot be sized up to a 391 the way the older 290 could be bumped to a 390. I agreed.
Fatherwheels
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It just goes to show what they think of their customers, when they couldn't make something decent, throw away junk is
all that range of saws is.
