If they appear damaged or deteriorated, replace them.

Balancer Adjustment
Torque LimiterOil Level Inspection
If the oil has just been changed, start
the engine and run it for severalminutes
at idle speed. This fills the oil
filter with oil. Stop the engine, then
wait several minutes until the oil settles.
NOTICE
Racing the engine before the oil
reaches every part can cause engine
seizure.
...
For Primary Fuel Injectors
Remove the air cleaner housing (see Air Cleaner Housing
Removal).
Disconnect the primary fuel injector connector [A].
Connect a digital meter to the terminals in each primary
fuel injector [A].
Measure the primary fuel injector resistance.
Primary Fuel Injector Resistance ...
Premuffler Chamber Installation
Replace the premuffler chamber gasket [A] with a new
one.
Install the premuffler chamber gasket to the premuffler
chamber [B] until it is bottomed so that the chamfer side
faces exhaust pipe [C].
Install the exhaust pipe clamp [D] as shown in the figure.
Insert the projection [E] into ...