Yamaha FX Nytro FX10X, Service Manual

Page: 446 / 859

5-32
ENG
VALVES AND VALVE SPRINGS
4. Remove:
• Upper spring seat
1
• Valve spring 2
• Valve
3
• Valve stem seal 4
• Lower spring seat
5
NOTE:
Identify the position of each part very carefully so
that it can be reinstalled in its original place.
INSPECTION
1. Measure:
• Valve-stem-to-valve-guide clearance
Out of specification
→
Replace the valve
guide.
Valve-stem-to-valve-guide clearance =
Valve guide inside diameter
a
–
Valve stem diameter
b
Valve-stem-to-valve-guide clearance:
Intake:
0.010 ~ 0.037 mm
(0.0004 ~ 0.0015 in)
<Limit>: 0.080 mm (0.0031 in)
Exhaust:
0.025 ~ 0.052 mm
(0.0010 ~ 0.0020 in)
<Limit>: 0.100 mm (0.0039 in)
2. Replace:
• Valve guide
NOTE:
To ease valve guide removal and installation, and
to maintain the correct fit, heat the cylinder head to
100 °C (212 °F) in an oven.
Replacement steps:
• Remove the valve guide with the valve guide
remover
1
.
• Install the new valve guide with the valve guide
installer
2
and valve guide remover
1
.
Valve guide position
a
:
14.8 ~ 15.2 mm
(0.583 ~ 0.598 in)