Stihl MS 650

77MS 650, MS 660
The diaphragm material, inlet and
outlet valves are subjected to
continuous alternating stresses and
eventually shows signs of fatigue,
i.e. the diaphragm distorts and
swells and has to be replaced.
: Inspect the fuel strainer (1) for
contamination and damage. If
necessary, remove it from the
carburetor and clean or replace.
Reassemble in the reverse
sequence.
178RA149
VA
1
: Place the gasket (2) on the end
cover (1).
: Place the diaphragm (3) on the
end cover (1).
: Line up the diaphragm and
gasket so that they are centered
178RA150
VA
2
3
1
2
3
1
by the cast pegs (arrows).
– Fit the carburetor on the end
cover.
The pump diaphragm, gasket and
end cover are held in position by
pegs on the end cover.
– Fit screw and tighten it down
firmly – b 3.5
Reassemble all other parts in the
reverse sequence.
– Remove the carburetor –
b 12.2.1
: Take out the screw (1).
1
178RA155
VA
– Set the throttle shaft to the full
throttle position.
: Carefully pull the throttle shutter
out of the shaft.
178RA156
VA
: Unscrew the idle speed screw
(LA) (1).
: In idle position, lever (2) butts
against carburetor (arrow).
178RA158
2
VA
1
12.3.5 Removing and Installing
the Throttle Shaft