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MS 290, MS 310, MS 390
English
27
The chain brake will operate only if the
hand guard has not been modified in any
way.
Check operation of the chain brake
Before starting work: Run engine at idle
speed, engage the chain brake (push
hand guard toward bar nose) and open
the throttle wide 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. STIHL recommends that you
have servicing and repair work carried
out exclusively by an authorized STIHL
servicing dealer. Maintain the following
servicing intervals:
At temperatures below +10 °C
N
Turn the knob above the rear handle
to the left – slot vertical
N
Pull off the carburetor box cover
toward the rear
N
Lift off the prefilter (1)
N
Unplug the spark plug boot (2) from
the spark plug
N
Pry the slide (3) out of the shroud
using a screwdriver
N
Turn the slide around by 180° and
reinsert it to the left next to the spark
plug
N
Press the spark plug boot onto the
spark plug again
Full-time usage:
every 3
months
Part-time usage:
every 6
months
Occasional usage:
every 12
months
Winter Operation
139BA016 KN
1
139BA001 KN
139BA002 KN
2
139B
A
0
05
T
R