The rings should fit perfectly parallel to groove surfaces.
If not, replace the piston and all the piston rings.
Piston Ring/Groove Clearance Standard:
Top 0.03 
0.07 mm (0.0012
0.0028 in.)
Second 0.03 
0.06 mm (0.0012
0.0024 in.)
Service Limit:
Top 0.17 mm (0.0067 in.)
Second 0.16 mm (0.0063 in.)
Piston Wear Inspection
Piston Ring Groove Width InspectionClutch Plate, Wear, Damage Inspection
Visually inspect the friction and steel plates for signs of
seizure, overheating (discoloration), or uneven wear.
Measure the thickness of each friction plate [A] at several
points.
If any plates show signs of damage, or if they have worn
past the service limit, replace them with new on ...
Cylinder (Upper Crankcase) Wear Inspection
Split the crankcase (see Crankcase Splitting).
Remove the pistons (see Piston Removal).
Assemble the cylinder (upper crankcase) [A], the cylinder
head [B] and the cylinder head gasket [C].
Tighten the cylinder head bolts (see Cylinder Head Installation
in the Engine Top End chapter).
...
Lighting System
This motorcycle adopt the daylight system and have a
headlight relay in the relay box. The headlight does not
go on when the ignition switch and the engine stop switch
are first turned on. The headlight comes on after the starter
button is released and stays on until the ignition switch is
turn ...