Yamaha 5YF2-AE1, Service Manual, Page: 113 / 262

4 - 17
ENG
CAMSHAFT, ROCKER ARMS AND VALVES
EBS00240
CHECKING THE VALVES AND VALVE
SPRINGS
1. Measure:
• stem-to-guide clearance
Out of specification
→
Replace the valve
guide.
2. Replace:
• valve guide
▼▼▼ ▼ ▼ ▼▼▼ ▼ ▼ ▼▼▼ ▼ ▼ ▼▼▼ ▼ ▼ ▼▼▼ ▼ ▼ ▼▼▼ ▼ ▼▼▼
NOTE:
_
To ease guide removal, installation and to
maintain correct fit, heat the cylinder head to
100 °C (212 °F) in an oven.
a. Remove the valve guide using a valve guide
remover
1
.
b. Install the new valve guide using a valve
guide remover
1
and valve guide installer
2
.
c. After installing the valve guide, bore the
valve guide using a valve guide reamer
3
to obtain proper stem-to-guide clearance.
NOTE:
_
After replacing the valve guide reface the valve
seat.
▲▲▲ ▲ ▲ ▲▲▲ ▲ ▲ ▲▲▲ ▲ ▲ ▲▲▲ ▲ ▲ ▲▲▲ ▲ ▲ ▲▲▲ ▲ ▲▲▲
Stem-to-guide clearance =
valve guide inside diameter
a
–
valve stem diameter
b
Stem-to-guide clearance
Intake
0.010 ~ 0.037 mm
(0.0004 ~ 0.0015 in)
<Limit>: 0.08 mm (0.0031 in)
Exhaust
0.025 ~ 0.052 mm
(0.0010 ~ 0.0020 in)
<Limit>: 0.10 mm (0.0039 in)
Valve guide remover (5 mm)
P/N. YM-04097, 90890-04097
Valve guide installer (5 mm)
P/N. YM-04098, 90890-04098
Valve guide reamer (5 mm)
P/N. 90890-04099