Servicing The Carburetor; Metering Diaphragm - Stihl SR 430 Manual

2
1
– Connect hose of pump
0000 850 1300 to the nipple.
: Push the ring (1) to the right and
pump air into the carburetor until
the pressure gauge (2) indicates
a pressure of about 0.8
bar (80 kPa).
If this pressure remains constant,
the carburetor is airtight. However, if
it drops, there are three possible
causes:
1 The inlet needle is not sealing
(foreign matter in valve seat,
sealing cone of inlet needleis
damaged or inlet control lever is
sticking). Remove to clean,
b 9.6.2
2 Metering diaphragm damaged,
replace if necessary, b 9.6.1
3 Pump diaphragm damaged,
replaceif necessary, b 9.6.4
– After completing the test, push
the ring (1) to the left to vent the
system and then pull the hose off
the carburetor's nipple.
– Install the carburetor, b 9.5
– Reassemble all other parts in the
reverse sequence.
64
9.6

Servicing the Carburetor

9.6.1

Metering Diaphragm

1
– Remove the carburetor, b 9.5
: Take out the screws (arrows).
– Remove the end cover (1).
If the gasket and diaphragm are
stuck to the carburetor, remove
them very carefully.
1
: Carefully separate the metering
diaphragm (1) and gasket (2).
The diaphragm material is
subjected to continuous alternating
stresses and eventually shows
signs of fatigue. i.e. the diaphragm
distorts and swells and has to be
replaced.
Installing
1
– Note installed positions of
metering diaphragm (1) and
gasket (2).
: Line up the gasket (2) and
metering diaphragm (1) with the
holes (arrows).
1
2
: Position the end cover (1) so that
the hose barb (2) is on the same
side as the adjusting screws.
– Fit the end cover.
2
2
SR 430, SR 450