Definition Of Optimum Setting For Idle Speed Mixture And High Speed Mixture Adjustments; Rocker Arm To Valve Clearance Adjustment - Toro AC-1 Service Manual

8. Final Idle Speed Adjustment: Adjust the idle
speed by turning the idle speed screw in (clock-
wise) or out (counterclockwise) until the cutting
head does not rotate.
Do
not squeeze the throttle
trigger when adjusting the idle speed screw.
9. Make sure the air filter cover is reinstalled securely
before placing the unit back into service.
Definition of Optimum Setting for Idle Speed
Mixture and High Speed Mixture Adjustments
Always set the idle speed mixture needle and high
speed mixture needle at the optimum setting. To find
the optimum setting, use the following procedure.
1. Turn the adjusting needle out (counterclockwise)
from the preliminary setting until the engine speed
decreases (rich). Note the position of the needle.
2. Turn the adjusting needle in (clockwise). The en-
gine speed may increase as the needle is turned
in (lean). Note the position of the needle.
3.
Set the adjusting needle midway between the rich
and the lean settings (Figure 1-16).
Midpoint
Adjust to
Lean
I
Figure 1-16. Optimum Setting.
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Rocker Arm to Valve Clearance Adjustment
Every 50 hours of operation, remove the rocker arm
cover and check the rocker arm to valve clearance.
1.
Remove the four
(4)
screws from the engine cover.
Remove the engine cover. Remove the rocker arm
cover. Refer to Part
3
-
Engine Disassembly.
2. Position the crankshaft so that the piston is at the
top of the compression stroke (both rocker arms
are free and loose).
3.
Measure the clearance between the valve stems
and rocker arms, using a flat feeler gauge (Figure
1-17).
Figure 1-17. Measuring the Rocker Arm to Valve
Clearance.
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The recommended rocker arm to valve clearance for
both the intake and exhaust is .003-.006 in
(.076 mm-,152 mm).