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.)
If the width of any of the two grooves is wider than the service limit at any point, replace the piston.
Piston Ring, Piston Ring Groove Wear Inspection
Piston Ring Thickness InspectionKIBS Servicing Precautions
There are a number of important precautions that should
be followed servicing the KIBS.
This KIBS is designed to be used with a 12 V sealed battery
as its power source. Do not use any other battery
except for a 12 V sealed battery as a power source.
Do not reverse the battery cable connec ...
Upper Crankcase Assembly
When installing the breather plate, replace the gasket [A]
with a new one.
Apply a non-permanent locking agent to the threads of
the bolts [A] and tighten them.
Torque - Breather Plate Bolts: 9.8 N·m (1.0 kgf·m, 87 in·lb)
Install the fitting [A] until it is bottomed ...
Exhaust Pipe Removal
Remove:
Radiator (see Radiator and Radiator Fan Removal in the
Cooling System chapter)
Exhaust Pipe Clamp Bolt [A] (Loosen)
Remove the exhaust pipe holder nuts [A], and pull out the
exhaust pipe [B] forward from the premuffler chamber.
...