The Forestry Forum

General Forestry => Chainsaws => Topic started by: derakicksyou on June 30, 2015, 07:18:20 PM

Title: Stihl 120 cutting off
Post by: derakicksyou on June 30, 2015, 07:18:20 PM
Trying to figure out why my Stihl 120 keeps cutting off.
It starts up and sounds fine and runs okay for a little while. After I make a bigger cut in the tree it will cut out on me almost immediately after I release the trigger. Sometimes after it has been running for a bit, it will also cut out on idle.
Any idea what adjustment to make or what is going on? I'm new to doing anything to a chainsaw aside from regular cleaning.

Also, what is the snowflake tab? I'm sure I was told but can't remember for the life of me.
(https://forestryforum.com/gallery/albums/userpics/40218/Stihl.jpg)
Title: Re: Stihl 120 cutting off
Post by: sawguy21 on June 30, 2015, 08:08:05 PM
Welcome to the FF.  8) It may be getting too hot and vapor locking, try enriching the mixture by turning the screws counter clockwise a tich. The snowflake indicates winter use, open the port to allow warm air to reach the carburetor. This prevents icing.
Title: Re: Stihl 120 cutting off
Post by: joe_indi on July 01, 2015, 12:50:21 PM
The metering lever that controls the fuel level is allowing more fuel than required into the metering chamber. This usually happens when the inlet needle is worn, which results in it sinking lower down in its well. This causes the metering lever to move up in the opposite direction so that it gets activated by the metering diaphragm earlier.
Next stage will be a flooding of the carb even when the engine is off.
Replace the inlet needle and st the metering level, then adjust the carb.
Title: Re: Stihl 120 cutting off
Post by: zandoval on July 05, 2015, 01:23:51 PM
Very interested in this post as I have the same problem developing in an old blower...

Be sure to post your solution...