MS 311, MS 391
English
52
Chain sprockets
In order to comply with the kickback 
performance requirements of Sec. 5.11 
of ANSI standard B 175.1-2000, do not 
use replacement saw chains unless they 
have been designated as meeting the 
ANSI Sec. 5.11 requirements on this 
specific engine unit, or have been 
designated as "low kickback" saw 
chains in accordance with the ANSI 
B 175.1-2000 standard.
Since new bar/chain combinations may 
be developed after publication of this 
Manual, ask your STIHL dealer for the 
latest STIHL recommendations.
Contact your STIHL dealer for 
information regarding special 
accessories that may be available for 
your product.
Chain scabbard
If you use guide bars of different lengths 
on the saw, the length of the chain 
scabbard must be matched to the guide 
bar to help reduce the risk of injury. 
If the chain scabbard does not cover the 
full length of the guide bar, a suitable 
chain scabbard or a scabbard extension 
is necessary.
Depending on the model, the scabbard 
extension either comes standard with 
the saw or is available as a special 
accessory.
Fitting the chain scabbard extension 
onto the scabbard
The scabbard extension has two square 
cut-outs (1) that fit onto one of several 
sets of locking tabs (2, 3, 4) located on 
the scabbard. Each set of locking tabs is 
marked with the lenght of the bar to 
which they correspond, given in 
centimeters on one tab and in inches on 
the other.
N Determine the appropriate set of 
tabs to be used based on the length 
the bar
N Push the scabbard extension over 
the scabbard until the cut-outs align 
with desired set of tabs, and let 
them lock together
7-tooth for 3/8" (rim sprocket)
Special Accessories
432
432
1
1
001BA209 KN
cm
INCH