Replace it if necessary.

Inner Tube Inspection
Spring Tension InspectionCrankshaft Removal
Split the crankcase (see Crankcase Splitting).
Remove:
Connecting Rod Big End Nuts [A]
Connecting Rod Big End Caps [B]
NOTE
Mark and record the locations of the connecting rods
and their big end caps so that they can be reassembled
in their original positions.
Remove the crank ...
Drive Chain Wear Inspection
Remove the chain cover (see Drive Chain Removal/Installation
in the Final Drive chapter).
Rotate the rear wheel to inspect the drive chain for damaged
rollers, and loose pins and links
If there is any irregularity, replace the drive chain.
Lubricate the drive chain if it appears dry.
...
Valve Seat Repair
Repair the valve seat with the valve seat cutters [A].
Special Tools - Valve Seat Cutter Holder Bar [B]: 57001
-1128
Valve Seat Cutter Holder, 4.5 [C]: 57001
-1330
[For Exhaust Valve Seat]
Valve Seat Cutter, 45° - 27.5:
57001-1114
Valve Seat Cutter, 32° - 28:
57001-1119
Valve Seat ...