If they appear damaged or deteriorated, replace them.

Balancer Adjustment
Torque LimiterCheck 3-5: Warning Indicator Light (Red LED) (Oil Pressure Warning)
Inspection
Connect the leads in the same circuit as Check 3-2.
Connect the terminal [10] to the battery (–) terminal.
Check that the oil pressure warning symbol [A] and the
warning indicator light (Red LED) [B] go on.
If the indicator light does not go on, replace the meter unit.
...
Valve Removal
Remove the cylinder head (see Cylinder Head Removal).
Remove the valve lifter and shim.
Mark and record the valve lifter and shim locations so they
can be installed in their original positions.
Using the valve spring compressor assembly, remove the
valve.
Special Tools - Valve ...
Exhaust Device
This motorcycle is equipped with a
exhaust device system. This system
controls the valve in the exhaust pipe
and produces stable engine power at
low and middle engine speed. This exhaust
device is controlled by the ECU,
and adjustment or maintenance should
be done only by a competent mechanic ...