Check the engine oil level as follows:

The engine oil level should be between "L" (Low) and "f" (full) lines.
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Caution The engine oil level must be between the " l'' (low) line and "f" (full) ~i ne, or engine damage may occur. Check the oil level, through the inspection window, with the motorcycle held vertically on level ground before each use of the motorcycle. |
Engine oil
Engine oil and filter changeCooling system inspection
Inspect cooling system
every 6 000 km (4 000 miles, 6 months)
Replace engine coolant
every 2 years
Engine coolant level inspection
Hold the motorcycle vertically.
Check the engine coolant level by observing the “f” and “l” lines on
the engine coolant reservoir tank. If the level i ...
Cam chain guide inspection
Inspect the cam chain guide in the following procedures:
remove the cam chain guides. Refer to “cam chain guide / cam chain
tensioner removal and installation” .
Check the contacting surface of the cam chain
guides. If it is worn or damaged, replace it with a new
one.
...
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.
...