Stihl BR 500 - Cranking; When engine begins to fire; At very low outside temperatures; Stopping the Engine

21BR 500, BR 550, BR 600
As a result of the alternating
stresses, the diaphragm material
and the inlet and outlet valves
eventually show signs of fatigue, i.e.
the diaphragm distorts and swells
and has to be replaced.
Install in the reverse sequence.
Use a new gasket.
: Place the gasket (1) on the
carburetor body so that the hole
in the gasket lines up with the
bore in the carburetor body
(arrows).
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: Place the metering diaphragm (1)
on the carburetor body so that the
perforated sheet (2) faces the
inlet control lever (3).
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3
: Line up the hole in the metering
diaphragm (1) with the bore in the
carburetor body.
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: Place the end cover (1) in
position.
Make sure the bore in the end cover
lines up with the hole in the
metering diaphragm (arrows).
– Fit the screws and tighten them
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down firmly, b 3.4
Install all other parts in the reverse
sequence.
– Remove the metering
diaphragm, b 6.3.1
: Take out the screw (1).
: Remove the inlet control lever (2)
with spindle.
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There is a small spring (arrow)
under the inlet control lever. It may
pop out during disassembly.
– Pull out the inlet needle (3).
: If there is an annular indentation
(arrow) on the sealing cone of the
inlet needle, replace the inlet
needle because it will no longer
seal properly.
VA
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6.3.2 Inlet Needle
RA_452_00_01_02.book Seite 21 Donnerstag, 16. Februar 2012 11:52 11