Instruction Manual

MS 271, MS 271 C, MS 291, MS 291 C
English
36
Basic information
The carburetor comes from the factory
with a standard setting.
The carburetor has been adjusted for
optimum performance and fuel
efficiency in all operating states.
Preparing the machine
N Switch off the engine
N Check the air filter – clean or replace
it if necessary
Standard setting
N Turn the high speed adjusting
screw (H) counterclockwise as far
as possible (max. 3/4 turn)
N Turn the low speed adjusting
screw (L) clockwise as far as
possible – then turn it 1/4 turn
counterclockwise
Setting the idle speed
N Make standard setting
N Start engine and let it warm up
Engine stops when idling
N Turn the idle speed adjusting
screw (LA) clockwise until the saw
chain begins to rotate – then turn it
back 1 turn
Saw chain rotates at idle speed
N Turn the idle speed screw (LA)
counterclockwise until the saw
chain stops turning – then turn
another full turn 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.
N Carefully turn the low speed
adjusting screw (L)
counterclockwise until the engine
runs and accelerates smoothly – but
no further than the stop
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:
N Make standard setting
N Let the engine warm up
N Turn the high speed adjusting
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.
Adjusting the Carburetor
L
5902BA035 KN
H
5902BA036 KN
LA