Servicing The Carburetor; 12.6.1 Metering Diaphragm - Stihl MS 201 Manual

2
1
– Push the pressure hose of pump
0000 850 1300 onto 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 needle
is damaged or
inlet control lever is sticking),
remove to clean,
b 12.6.2
2. Metering diaphragm or gasket
damaged, replace as
necessary,
b 12.6.1
3. Pump diaphragm or
gasket damaged,
replace as necessary, b 12.6.3
– After completing the test, push
the ring (1) to the left to vent the
system and then pull the fuel
hose off the carburetor's stub.
– Install the filter base,
MS 201 b 12.3,
MS 201 T b 12.3.1
– Reassemble all other parts in the
reverse sequence.
MS 201, MS 201 C, MS 201 T, MS 201 TC
12.6

Servicing the Carburetor

12.6.1 Metering Diaphragm

– Troubleshooting, b 3.6
– Remove the carburetor,
MS 201 b 12.4,
MS 201 T b 12.5
: Take out the screws (arrows).
: Remove the end cover (1).
If the gasket and diaphragm are
stuck to the carburetor, remove
them very carefully.
2 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.
– Check the metering diaphragm
for signs of damage and wear.
Install a new gasket.
Installing
2
1
1
: Note installed positions of
metering diaphragm (2) and
gasket (1).
: Position the gasket (1) and
metering diaphragm (2) so that
the small holes (arrows) line up
with the recess and the small
hole in the carburetor.
: Position the end cover (1) so that
the stub (arrow) points in the
direction of the choke shutter.
: Fit the end cover (1) so that its
fixing pin engages the gasket,
metering diaphragm and the bore
in the carburetor.
1
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