Stumpzero
Stump Zero Stump Grinding
It was running this high before the meltdown.
Brand new MS391 meltdown
- Thread starter Stumpzero
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Still...check for air leaks. No leaks...adjust carb. This is a perfect saw to learn on.
Stumpzero
Stump Zero Stump Grinding
I will do it.
Good plan! Too bad the learning had to happen this way but now you're making lemons into lemonade. Good luck.
You've come a long ways with her.
Surprised to hear that a brand new saw had the idle cranked up like that, dealer error.
Turn the idle screw CCW to tame.
Surprised to hear that a brand new saw had the idle cranked up like that, dealer error.
Turn the idle screw CCW to tame.
I would check that linkage to the carb carefully.
If you can do that kind of clean up you can figure that carb out easy enough.
Make sure the throttle linkage is not sticking, or the butterfly sticking in the barrel for that matter.
If that is the case it is a defect. Call the Stihl rep if it comes to that.
If you can do that kind of clean up you can figure that carb out easy enough.
Make sure the throttle linkage is not sticking, or the butterfly sticking in the barrel for that matter.
If that is the case it is a defect. Call the Stihl rep if it comes to that.
You should be able to turn the larger idle speed screw CCW until the engine almost stalls due to a low idle. If not, look for the air leak as previously directed. If it goes low but the chain does not stop, you have a clutch issue.
One quick thing to try, put the brake on at idle. The clutch could have backed off and is binding.
DO NOT LEAVE THE BRAKE ON! Just a quick on and off.
One quick thing to try, put the brake on at idle. The clutch could have backed off and is binding.
DO NOT LEAVE THE BRAKE ON! Just a quick on and off.
I don't see any way they let the saw out of the plant with the idle off that much.
I'll be interested to see if the idle speed screw slows it down or not.
I'll be interested to see if the idle speed screw slows it down or not.
I’ve seen this issue on a number of 271s, 291s, and at least one straight carb 261. For some reason they come brand new with a VERY HIGH RPM when in hi idle. I fix saws for some local clubs and schools and of course they teach the students to start the saw with the chain break On. If the student isn’t taught to immediately take the brake Off the saw will run against the brake, overheating the clutch real quick and melting everything around it. The cure is trimming a plastic piece linkage on the carb that holds the throttle open in high idle. I can’t understand why Stihl hasn’t fixed this common problem.All put back together, oil pump adjusted. Zero binding on the Chain brake. Zero binding on the chain sprocket/clutch drum. Chain brake works perfect. Chain Oiler working great. Saw seems to beready to go.
I even sharpened my first chain and put it on this saw. Nice to have a back up/ Second saw on my trailer. The low Idle seems to be very high still. High Idle seems to be very high as well. I’m going to take it by the dealer to see what they think
As this is my first chain saw not sure on what the idle should be like but comparing it to the second saw I purchased (same exact model) it idles much much faster.
View attachment 1243509
All put back
Not an air leak problem and the idle adjust screw doesn’t work when you are in hi idle. It is a carb linkage issue. You are correct in saying take brake off immediately.
Stumpzero
Stump Zero Stump Grinding
It comes off high idle fine it’s just that once on low Idle it’s very very high. Higher than the high idle on my second identical saw. I will try lowering it today and post what I find.
Stumpzero
Stump Zero Stump Grinding
Ohhhhhh I learned the hard way CHAIN BREAK OFFFFFFF.
That’s how it’s supposed to work. Why it’s called high idle
TOTALCHAOS69
ArboristSite Lurker
Clutch bearing on a new 391 has plastic cage. Echo stuff is metal. 
