Replace it if necessary.

Inner Tube Inspection
Spring Tension InspectionGeneral Lubrication
Lubricate the points shown below,
with either motor oil or regular grease,
in accordance with the Periodic Maintenance
Chart or whenever the vehicle
has been operated under wet or rainy
conditions.
Before lubricating each part, clean off
any rusty spots with rust remover and
wipe off any g ...
Piston Ring Groove Width Inspection
Measure the piston ring groove width.
Use a vernier caliper at several points around the piston.
Piston Ring Groove Width
Standard:
Top [A] 0.82 0.84 mm (0.0323
0.0331 in.)
Second [B] 0.82 0.84 mm
(0.0323 0.0331 in.)
Service Limit:
0.92 mm (0.036 in.)
Second 0.92 mm (0.036 in.)
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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.
...