Toro AC-1 Service Manual page 17

If the following conditions are experienced, it may be
necessary to adjust the carburetor.
The engine will not idle
The engine hesitates or stalls on acceleration.
The loss of engine power, which is not corrected
by cleaning the air filter, muffler, spark arrester
screen or adjusting the rocker arm to valve
clearance
The engine operates in an erratic or fuel-rich
condition
NOTE: Follow these carburetor adjustment proce-
dures carefully. An incorrectly adjusted carburetor can
cause severe engine damage.
Make sure the unit is fully assembled before
making carburetor adjustments.
For trimmers and brushcutters, make sure
the boom, cutting head, and line guard are installed
and the cutting line is extended to its full cutting length.
The carburetor has three basic adjustments: the idle
speed adjustment, the idle speed mixture adjustment,
and the high speed mixture adjustment (Figure 1-15).
Mixture Needle
Figure 1-1 5. Carburetor Adjustments.
3.6051.015
407000001-Use the following carburetor adjustment
instructions:
1. Initial Idle Speed Setting: Turn the idle speed
screw until it stops.
2. Initial High Speed Mixture and Idle Speed Mix-
ture Settings: Turn both the high speed mixture
and idle mixture needles in (clockwise) until they
are lightly seated.
3. Turn the needles o
u t
the
following number of turns:
High Speed Mixture Needle: 1 turn
Idle Speed Mixture Needle: 1 turn
NOTE: Turn the high speed mixture and idle mixture
needles finger-tight. Do not force the needles with a
screwdriver as this can damage the tips of the needle
and the seats in the carburetor body.
4. Start the engine and let it run for 3 to 5 minutes
with the throttle lever fully squeezed.
5. Release the throttle trigger and let the engine idle.
Turn the idle speed screw out (counterclock-
wise) until the speed decreases and the bump
head stops rotating.
6. Final Idle Speed and Mixture Adjustments:
Adjust the idle speed screw and idle speed mix-
ture needle for the smoothest engine idle using
the following procedure. Do not squeeze throttle
trigger when adjusting the idle speed screw and
idle speed mixture needle.
a. Set the idle speed mixture needle
at the optimum setting
(Figure 1-16). See "Definition of Optimum
Setting" on page 1-1 5.
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