Safety Manual

MS 251, MS 251 C
English
38
felling cut. The chain brake will operate
only if it has been properly maintained
and the hand guard has not been
modified in any way.
Check operation of chain brake
Before starting work: Run engine at idle
speed, engage the chain brake (push
hand guard toward bar nose).
Accelerate up to full throttle for no more
than 3 seconds – the chain must not
rotate. The hand guard must be free
from dirt and move freely.
Chain brake maintenance
The chain brake is subject to normal
wear. It is necessary to have it serviced
and maintained regularly by trained
personnel, such as your STIHL servicing
dealer, at the following intervals:
Preheating the carburetor
N Remove the shroud – see "Shroud".
At temperatures below +50°F (+10°C)
N Use a screwdriver to pry the shutter
out of the summer position (s).
N Fit the shutter in the winter
position (r) with its opening facing
the chain saw – the shutter must
engage audibly in position.
N Install the shroud – see "Shroud".
Heated air is now drawn in from around
the cylinder to warm the carburetor – this
helps prevent carburetor icing.
At temperatures above +70°F (+20°C)
N Always return the shutter to the
summer position (s ) to avoid
engine running problems and
overheating.
At temperatures below +14°F (-10°C)
N If your saw is very cold (frost or ice
on machine), start the engine and
keep it at a high idle speed (with
chain brake disengaged) until it
reaches normal operating
temperature.
If idling behavior is erratic or
acceleration is poor:
N Turn the low speed screw (L) 1/4 of
a turn counterclockwise.
It is usually necessary to change the
setting of the idle speed screw (LA) after
every correction to the low speed
screw (L) – see "Adjusting the
Carburetor".
Filter system
N Convert the air filter if necessary –
see "Air Filter System".
Full-time usage: every 3
months
Part-time usage: every 6
months
Occasional usage: every 12
months
Winter Operation
2310BA000 KN
2310BA001 KN