Stihl FS 450 Instruction Manual - Page 33

Motor Management, Adjusting the Carburetor

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English / USA Motor Management Adjusting the Carburetor 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. 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 : Shut off the engine. : Mount approved cutting tool. : Check the air filter and replace if necessary. : Check adjustment of the throttle cable and readjust if necessary - see "Adjusting the Throttle Cable". H 3/4 L 1 LA 255BA001 KN : Turn high speed screw (H) counterclockwise (max. 3/4 turn) as far as stop. : Carefully screw the low speed screw (L) down onto its seat. Then open it one turn counterclockwise. : Start the engine and run it until it is warm. : Adjust idle speed with the idle speed screw (LA) so that the cutting tool does not rotate. 32 FS 300, FS 350, FS 400, FS 450, FS 480

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32
English / USA
FS 300, FS 350, FS 400, FS 450, FS 480
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.
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
:
Shut off the engine.
:
Mount approved cutting tool.
:
Check the air filter and replace if
necessary.
:
Check adjustment of the throttle
cable and readjust if necessary –
see "Adjusting the Throttle Cable".
:
Turn high speed screw (
H
)
counterclockwise
(max.
3
/
4
turn)
as
far as stop.
:
Carefully screw the low speed
screw (
L
) down onto its seat. Then
open it
one
turn counterclockwise.
:
Start the engine and run it until it is
warm.
:
Adjust idle speed with the idle speed
screw (
LA
) so that the cutting tool
does not rotate.
Motor Management
Adjusting the Carburetor
255BA001 KN
LA
1
L
H
3/4