Yamaha TT-R125(N) Owner's Service Manual page 270

VALVES AND VALVE SPRINGS
3. Install:
NOTE:
While compressing the valve spring with a
valve spring compressor 2, install the valve
cotters.
4. To secure the valve cotters onto the
CAUTION:
Hitting the valve tip with excessive force
could damage the valve.
4 - 31
Valve cotters 1
Valve spring compressor:
YM-4019/90890-04019
valve stem, lightly tap the valve tip with a
piece of wood.
ENG