Engine Management; Adjusting The Carburetor - Stihl SR 430 Instruction Manual

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.
SR 430, SR 450

Adjusting the Carburetor

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 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".
N Have the spark arresting screen
(not all markets) checked – see
"Inspection and Maintenance by
Dealer".
L
H
LA
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 1 turn.
N Start and warm up the engine.
Adjusting Idle Speed
Engine stops while idling
N Check the standard setting.
N
Turn the idle speed screw (LA)
slowly clockwise until the engine
runs smoothly.
Erratic idling behavior, engine stops
even though setting of LA screw has
been corrected, poor acceleration
Idle setting is too lean
N Turn the low speed screw (L) slowly
counterclockwise until the engine
runs and accelerates smoothly.
Erratic idling behavior
Idle setting is too rich
N Turn the low speed screw (L)
clockwise until the engine runs and
accelerates smoothly.
English
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