If they appear damaged or deteriorated, replace them.

Balancer Adjustment
Torque LimiterLower Crankcase Assembly
Install the ball bearing [A] and the oil level inspection window
[B] until they are bottomed
Apply soap and water solution to the oil level inspection
window before installation.
Install the new circlip [C].
Apply a non-permanent locking agent to the oil passage
plug [D].
Tighten: ...
Idle Speed Control Valve Actuator Installation
Replace the O-ring [A] with a new one.
Apply engine oil to the new O-ring.
Install the idle speed control valve [A] as shown in the
figure.
10° [B]
Tighten:
Torque - Idle Speed Control Valve Actuator Retainer
Screws: 2.06 N·m (0.21 kgf·m, 18 in·lb)
Install th ...
Tachometer
The tachometer shows the engine
speed in revolutions per minute (r/min,
rpm).
On the right side of the tachometer
face is a portion called the “red zone”.
Engine r/min (rpm) in the red zone is
above maximum recommended engine
speed and is also above the range for
good performance.
...