If the fuel level indicator light (1) does not function properly, check the fuel level gauge and its lead wire/ coupler.
If the fuel level gauge and its lead wire/coupler are functioning properly, replace the combination meter with a new one.

Engine coolant temperature indicator light inspection
Fuel level gauge inspectionFi system troubleshooting
Customer complaint analysis
Record details of the problem (failure, complaint) and how it occurred as
described by the customer. For this purpose,
use of such an inspection form such as following will facilitate collecting
information to the point required for proper
analysis and diagnosis.
...
Engine oil and filter change
Change the engine oil and oil filter
at the scheduled times. The
engine should always be warm
when the oil is changed so the oil
will drain easily. The procedure is
as follows:
Place the motorcycle on the
side stand.
Remove the three screws of
the right fairing 1.
...
Battery charging
Initial charging
filling electrolyte
Note
when filling electrolyte, the battery must be
removed from the vehicle and must be put on
the level ground.
Remove the aluminum tape (1) which seals the
battery filler holes “a”.
Remove the caps (2) from the electrolyte ...