Adjustment (Carburetor Without Limiter Caps) - Stihl MS 440 Service Manual

The diaphragm material and the
inlet and exhaust valves are
subjected to continuous alternating
stresses and ultimately show signs
of fatigue. The diaphragm distorts
and swells and has to be replaced.
1
: Inspect the fuel strainer (1) for
contamination and damage. If
necessary, use a needle to
remove it from the carburetor
body and clean or replace it.
: Place the gasket (1) on the end
cover (2).
: Wet the pump diaphragm (3) with
fuel and place it on the gasket.
MS 440, MS 440 C
– Place the end cover on the
carburetor body.
The pump diaphragm, gasket and
end cover are located by the pins
integrally moulded onto the end
cover.
– Insert the screw and tighten it
down.
3
1
2
12.4 Adjustment (carburetor
without limiter caps)
1 2
Standard setting
(without tachometer)
The standard setting must be made
first when setting a new machine.
– Slowly turn both adjusting screws
H (1) and L (2) clockwise into
their seats.
Then adjust as follows:
– Back off high speed screw H
one turn.
– Back off low speed screw L
one turn.
If a tachometer is not available, the
high speed screw H must not be set
to a leaner setting than the standard
setting.
Standard setting
(with tachometer)
– Check air filter and clean or
replace it if necessary.
– Check the spark arresting screen
if installed and clean or replace it
if necessary.
– Check the chain tension.
– Let the engine warm up.
– Adjust engine idle speed.
71