Service Manual

Single Stage Snowthrower Service Manual 3 - 3
CONTROLS/LOCATION AND OPERATION
CHOKE
The carburetor choke control, or shutter, meters the
amount of air passing into the engine. When starting
the engine, the carburetor choke should be closed
(Figure 13). If your snowthrower has either the choke
cable, choke rod, or handle design to close the choke
shutter, the cable, rod, or handle should be pulled out.
If you have a single stage snowthrower manufactured
in 1980, the choke control should be rotated clockwise
to close the shutter, counterclockwise to open the
shutter.
Figure 13 0217-009
Closing the choke shutter allows air to enter the
carburetor only through openings in and around the
choke shutter (Figure 14). When the engine is
cranked, a low pressure area is created in the engine
and it extends into the carburetor. Since only a limited
amount of air can enter this low pressure area because
of the closed choke shutter, a greater amount of fuel is
drawn through the fuel passages to fill the void. This
creates the richer mixture needed for engine starting
and restarting after the engine is warm.
Figure 14 0217-010
After the engine starts, more air must pass into the
engine. Therefore, after the engine is started, open the
choke shutter to allow more air to pass into the engine.
Again, to open the choke shutter on those models that
have a choke cable, rod, or handle, push the choke
control lever in. On 1980 snowthrowers, the choke
control lever should be rotated counterclockwise.
THROTTLE: On Toro applications, the carburetor
throttle is controlled by the governor only. Therefore,
Toro single stage snowthrowers, are not equipped with
an engine speed control for the operator.
ON/OFF IGNITION SWITCH
The ignition switch found on Toro single stage
snowthrowers produced since 1975, allows the engine
to be started when the key is in the ON position.
Rotating the key to the OFF position will stop the
engine by allowing magneto current to flow to ground
(Figure 12).