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 playEct sensor removal and installation
Removal
Remove the left side cowling. Refer to “exterior parts removal and
installation” in section 9d .
Drain engine coolant. Refer to “cooling system inspection” in section
0b .
Disconnect the coupler and remove the ect sensor
(1).
Caution
take special care ...
Gearshift shaft / gearshift cam plate removal
and installation
Removal
Remove the engine sprocket cover. Refer to “engine sprocket removal and
installation” in section 3a .
Remove the clutch components. Refer to “clutch removal” in section 5c .
Remove the snap ring (1) and washer (2) from the
gearshift shaft.
Special tool
: 09900–06 ...
DTC “c31” (p0705): gp switch circuit
malfunction
Detected condition and possible cause
Detected condition
Possible cause
No gear position switch voltage
Gp switch voltage is not within the following range.
Gp switch voltage > 0.6 V
Gp switch circuit open or short.
Gp switch malfunction.
...