Service Manual

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Auto Choke System / Function
A. Governor Rod - Connected to the governor system
which controls the angle of the throttle plate and sets
engine operating RPM.
B. Thermal Spring Rod - Connected to the thermal
spring, which mounts on the muffler. The thermal spring
adjusts the choke plate angle as the engine temperature
changes.
C. Air Vane Rod - Connected to the air vane in the
blower housing which will fully open the choke plate at
full operating RPM at any engine temperature.
COLD START - Picture 1 illustrates the choke plate
position while starting a cold engine. The thermal spring
is cold, keeping the choke closed. The air vane is
inactive because the engine is not running.
HOT START - Picture 2 illustrates the maximum amount
the thermal spring can open the choke plate while the
engine is hot and not running.
FULL RPM - Picture 3 illustrates the maximum amount
the air vane can open the choke plate. When engine
RPM decreases, the choke will close, however if the
engine is hot, the thermal spring will prevent the choke
from fully closing.
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