Yamaha YZ426F(M)/LC Owner's Service Manual page 290

VALVES AND VALVE SPRINGS
REMOVAL POINTS
1. Remove:
NOTE:
Identify each lifter 1 and pad 2 position very
carefully so that they can be reinstalled in their
original place.
2. Check:
Checking steps:
3. Remove:
NOTE:
Attach a valve spring compressor 1 and
attachment 2 between the valve spring
retainer and the cylinder head to remove the
valve cotters.
4 - 28
Valve lifters 1
Pads 2
Valve sealing
Leakage at the valve seat → Inspect
the valve face, valve seat and valve
seat width.
Pour a clean solvent 1 into the intake and
exhaust ports.
Check that the valve seals properly.
There should be no leakage at the valve
seat 2.
Valve cotters
Valve spring compressor:
YM-04019/90890-04019
Attachment:
YM-04108/90890-04108
ENG