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 playOil jet removal and installation
Piston cooling oil jet
Removal
Remove the engine assembly. Refer to “engine assembly removal” in
section 1d .
Remove the crankshaft assembly. Refer to “engine
bottom side disassembly” in section 1d (page 1d-
49).
Remove the piston cooling oil jets (1) from the upper
cra ...
Side-stand / ignition interlock system parts
inspection
Check the interlock system for proper operation. If the
interlock system does not operate properly, check each
component for damage or abnormalities. If any
abnormality is found, replace the component with a new
one.
Side-stand switch
Turn the ignition switch off.
Remove the left si ...
DTC “c28” (p1655): secondary throttle
valve actuator (stva) malfunction
Detected condition and possible cause
Detected condition
Possible cause
The operation voltage does not reach the stva.
Ecm does not receive communication signal from the
stva. Stva can not operate properly or its motor locked
Stva malfunction.
...