Adjust the engine idle speed periodically on the engine at normal operating temperature.
To adjust the idle speed:

Engine oil and filter change
Throtile cable playCrankcase breather (pcv) hose / reed
valve / cover removal and installation
Removal
Lift and support the fuel tank with the prop stay.
Refer to “fuel tank removal and installation” in section 1g .
Remove the air cleaner box. Refer to “air cleaner box removal and
installation” in section 1d .
Disconnect the crankcase breather (pcv) hose (1).
...
Water hose removal and installation
Removal
Remove the side cowlings. Refer to “exterior parts
removal and installation” in section 9d (page 9d-
6).
Drain engine coolant. Refer to “cooling system inspection” in section
0b .
Lift and support the fuel tank. Refer to “fuel tank
removal and installation” in se ...
Continuity check
Measure resistance across coupler “b” (between “a”
and “c” in figure).
If no continuity is indicated (infinity or over limit), the
circuit is open between terminals “a” and “c”.
Disconnect the coupler “b” and measure resistance
between couplers “a” and “b-1”.
If no continuity ...