Engine Management; Adjusting The Carburetor - Stihl FS 300 Instruction Manual

English

Engine Management

Exhaust emissions are controlled by the
design of the fundamental engine
parameters and components (e.g.
carburation, ignition, timing and valve or
port timing) without the addition of any
major hardware.
24

Adjusting the Carburetor

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
adjust the high speed screw within fine
limits.
Standard Setting
N
Shutting off the engine
N Mount the cutting attachment.
N Check the air filter and replace it if
necessary.
N Check that the throttle cable is
properly adjusted – readjust if
necessary – see chapter on
"Adjusting the Throttle Cable".
L
H
1
3/4
LA
N Turn high speed screw (H)
counterclockwise as far as stop (no
more than 3/4 turn).
N Carefully turn the low speed
screw (L) clockwise down onto its
seat, then turn it back one full turn
counterclockwise.
N
Warm up the engine.
N Adjust idle speed with the idle speed
screw (LA) so that the cutting
attachment does not turn.
Adjusting Idle Speed
Engine stops while idling
N
Carry out standard setting on low
speed screw (L).
N Turn the idle speed screw (LA)
slowly clockwise until the engine
runs smoothly – the cutting
attachment must not rotate.
Cutting attachment rotates when
engine is idling
N Turn the idle speed screw (LA)
counterclockwise until the cutting
attachment stops moving and then
rotate the screw another 1/2 to 1
turn in the same direction.
FS 300, FS 350, FS 400, FS 450, FS 480