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 InspectionSprocket Wear Inspection
Visually inspect the engine and rear sprocket teeth for
wear and damage.
If the teeth are worn as illustrated, replace the sprocket,
and inspect the drive chain wear (see Drive Chain Wear
Inspection in the Periodic Maintenance chapter).
Worn Tooth (Engine Sprocket) [A]
Worn Tooth (Rear ...
Crankcase Halves Assembly
Install:
Crankshaft (see Crankshaft Installation)
Connecting Rods (see Connecting Rod Installation)
Using a cleaning fluid, clean off any oil or dirt on the mating
surface of the crankcase halves.
Apply liquid gasket to the mating surface of the lower
crankcase half as shown in the fi ...
Lubrication
Lubrication is necessary after riding
through rain or on wet roads, or any
time that the chain appears dry.
Use a lubricant for sealed chains to
prevent deterioration of chain seals. If
the chain is especially dirty, clean it
using a cleaner for sealed chains following
the instructions suppli ...