Toro 51643 Service Manual page 30

Carburetor Adjustment Mixture
1.
A
CAUTION: stay clear
of
cutter
head whenever engine is
running.
The high speed mixture screw (see Figure
34)
controls the fuel flow requirements during the
engine's optimum demand. With the engine
running at operating temperature, the choke fully
opened and, no load applied to the engine, turn the
high speed mixture screw to obtain the highest
RPM. This should be approximately2
to 3 turns
out
from fully closed.
Turning the screw clockwise will make the air/fuel
mixture lean (less fuel/more air).
Turning the screw counterclockwise will make the
air/fuel mixture rich (more fuel/less air).
IMPORTANT: Turning the high speed mixture
screw in too tightly may damage the tip.
Carburetor Adjustment Throttle Valve
CAUTION: Stay clear of cutter
head whenever engine is
running.
1.
Remove two screws securing the air cleaner cover
to the trimmer and remove the air cleaner as an
assembly.
2. Squeeze the throttle trigger and note the travel
o f
throttle valve in the carburetor opening. The
throttle valve should travel to the top
o f
the
carburetor opening when the trigger is in
full
throttle position.
3.
To adjust, loosen the jam nut on throttle cable and
rotate the turnbuckle to increase or decrease the
travel of the throttle valve. See Figure 34.
--
TURNBUCKLE
JAM NUT
Figure
34
4. Tighten the jam nut and check the adjustment.
5. Reinstall the air cleaner cover assembly and
secure using the two screws with flat washers and
lock washers.
6.
Check the idle speed and adjust if necessary. Refer
to Carburetor Adjustment Idle Speed, page
18.
19