If they appear damaged or deteriorated, replace them.

Balancer Adjustment
Torque LimiterClutch Lever Installation
Install the clutch lever so that the mating surface [A] of the
clutch lever clamp is aligned with the punch mark [B] of
the handlebar.
Tighten the upper clamp bolt first, and then the lower
clamp bolt.
Torque - Clutch Lever Clamp Bolts: 7.8 N·m (0.80 kgf·m, 69
in·lb)
There will be ...
Cylinder (Upper Crankcase) Wear Inspection
Split the crankcase (see Crankcase Splitting).
Remove the pistons (see Piston Removal).
Assemble the cylinder (upper crankcase) [A], the cylinder
head [B] and the cylinder head gasket [C].
Tighten the cylinder head bolts (see Cylinder Head Installation
in the Engine Top End chapter).
...
Thermostat Installation
Replace the O-rings [A] with new ones, and apply grease
to them.
Assemble:
O-rings
Thermostat Housing [B]
Thermostat [C]
Thermostat Cap [D]
Install the thermostat [A] in the housing so that the air
bleeder hole [B] is on top.
Tighten:
Torque - Thermostat Cap Bolts: 5.9 N ...