Spark Arresting Screen In Muffler - Stihl MS 251 Instruction Manual

Engine stops when idling
Turn the idle speed adjusting screw
N
(LA) clockwise until the saw chain
begins to run – then turn it back
2 3/4 turn.
Saw chain rotates at idle speed
Turn the idle speed screw (LA)
N
counterclockwise until the saw
chain stops turning – then turn
another 2 3/4 turns in the same
direction
WARNING
If the saw chain continues to keep
rotating in idle even after adjustment,
have the chain saw checked by a
servicing dealer.
Speed erratic when idling; poor
acceleration (despite standard setting of
low speed adjusting screw)
The idle setting is too lean.
Carefully turn the low speed
N
adjusting screw (L)
counterclockwise until the engine
runs smoothly and accelerates
properly.
MS 251, MS 251 C
Whenever the low speed adjusting
screw (L) has been adjusted, it is usually
also necessary to readjust the idle
speed adjusting screw (LA).
Correcting the carburetor setting for use
at high altitudes
The setting may have to be marginally
corrected if engine performance is
unsatisfactory at high altitudes:
Make standard setting
N
Let the engine warm up
N
Turn the high speed adjusting
N
screw (H) slightly clockwise (leaner)
– max. up to the stop
NOTICE
After descending from a high altitude,
restore the carburetor setting to the
standard setting.
If you make the setting too lean it will
increase the risk of engine damage
through lack of lubrication and
overheating.
Spark Arresting Screen in
Muffler
If engine performance deteriorates,
N
check the spark arresting screen in
the muffler
Let the muffler cool down
N
1
2
Unscrew the screw (1)
N
Pull out spark arresting screen (2)
N
Clean the dirty spark arresting
N
screen, replace if damaged or
heavily carbonized
Refit the spark arresting screen
N
Fit screw
N
English
45