MS 251, MS 251 C
English
35
Releasing the chain brake
N Pull the hand guard back toward the
front handle.
NOTICE
Always disengage chain brake before
accelerating engine and before starting
cutting work. The only exception to this
rule is when you check operation of the
chain brake.
High revs with the chain brake engaged
(chain locked) will quickly damage the
powerhead and chain drive (clutch,
chain brake).
The chain brake is designed to be
activated also by the inertia of the front
hand guard
if the forces are sufficiently high. The
hand guard is accelerated toward the
bar nose - even if your left hand is not
behind the hand guard, e.g. during a
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.
Full-time usage: every 3
months
Part-time usage: every 6
months
Occasional usage: every 12
months
Winter Operation
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