Instruction Manual

MS 311, MS 391
English
33
Exhaust emissions are controlled by the
design of the engine and components
(e.g. carburation, ignition, timing and
valve or port timing).
General Information
The carburetor comes from the factory
with a standard setting.
This setting provides an optimum fuel-air
mixture under most operating
conditions.
With this carburetor it is only possible to
correct the adjusting screws within fine
limits.
Standard Setting
N Shut off the engine.
N Check the air filter and clean or
replace if necessary.
N Check the spark arresting screen in
the muffler and clean or replace if
necessary.
N Turn high speed screw (H)
counterclockwise as far as stop (no
more than 3/4 turn).
N Turn the low speed screw (L)
carefully clockwise as far as stop,
then turn it back a 1/4 turn.
Adjusting Idle Speed
N Carry out the standard setting.
N Start and warm up the engine.
Engine stops while idling
N Turn the idle speed screw (LA)
clockwise until the chain begins to
run – then back it off 1 1/2 turns.
Saw chain runs while engine is idling
N Turn the idle speed screw (LA)
counterclockwise until the chain
stops running – then turn it another
1 1/2 turns in the same direction.
WARNING
If the chain continues moving when the
engine is idling, have your saw checked
and repaired by your servicing dealer.
Erratic idling behavior, poor acceleration
(even though low speed screw is open 1
turn)
Idle setting is too lean
N Turn the low speed screw (L)
counterclockwise until the engine
runs and accelerates smoothly.
Engine Management Adjusting the Carburetor
L
0001BA027 KN
L
LA
0001BA028 KN