Yamaha F40BMHD, Service Manual, Page: 230 / 537

POWR
5-31
CYLINDER HEAD
E
3. Measure:
• Valve seat width
Out of specification
→
Reface the
valve seat.
CHECKING THE VALVE
1. Check:
• Valve
Deformation
→
Replace.
2. Measure:
• Margin thickness
Out of specification
→
Replace.
3. Measure:
• Valve stem diameter
Out of specification
→
Replace.
4. Measure:
• Valve stem run-out
Out of specification
→
Replace.
NOTE:
The valve guide and valve stem seal should
be replaced when the valve is replaced.
a
Valve seat width
0.9 - 1.1mm
(0.035 - 0.043 in)
a
a
a
Margin thickness
IN 0.6 - 1.0 mm
(0.024 - 0.039 in)
EX 0.7 - 1.1 mm
(0.028 - 0.043 in)
Valve stem diameter
IN 5.475 - 5.490 mm
(0.2156 - 0.2161 in)
EX 5.460 - 5.475 mm
(0.2150 - 0.2155 in)
a
a
Stem run-out limit
IN, EX 0.016 mm (0.0006 in)