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 InspectionEngine Oil Flow Chart
1. Oil Screen
2. Oil Pump
3. Oil Pressure Relief Valve
4. Oil Filter
5. Oil Pipe
6. Oil Cooler
7. Balancer Oil Passage
8. Main Oil Passage
9. Crankshaft Oil Passage
10. Oil Pressure Switch
11. Camshaft Oil Passages
12. Drive Shaft Oil Passage
13. Output Shaft Oil Passage
14. Starter ...
For Primary Fuel Injectors
Remove the air cleaner housing (see Air Cleaner Housing
Removal).
Disconnect the primary fuel injector connector [A].
Connect a digital meter to the terminals in each primary
fuel injector [A].
Measure the primary fuel injector resistance.
Primary Fuel Injector Resistance ...
Swingarm Installation
Visually inspect the chain guide [A].
Replace the chain guide if it shows any signs of abnormal
wear or damage.
Apply a non-permanent locking agent to the threads of
the chain guide bolt [B].
Apply plenty of grease to the lip of the oil seals [A].
Be sure to install the oil seals ...