Yamaha EF1000iS Service Manual page 64

CYLINDER (CRANKCASE 1) AND VALVE
a
c
6. Remove the carbon deposits on the valve
face a and valve seat.
9 Valve face contact seat width b
9 Valve margin thickness c
9 Valve margin thickness
b
9 Valve face contact width
3-34
ENG
Apply a small amount of coarse
mechanic's blueing dye (Dykem) to the
valve seat.
Press the valve through the valve guide
and onto the valve seat to make a clear
impression.
Out of specification → Replace.
Out of specification → Replace.
Valve seat width:
(Intake/Exhaust)
0.8 mm (0.03 in)