Replacing The Valve Guides - Yamaha F2.5A Service Manual

POWR
2. Calculate the valve stem-to-valve guide
clearance as follows. Replace the valve
guide if out of specification.
Valve stem-to-valve guide clearance
= valve guide inside diameter – valve
stem diameter:
Intake:
0.010–0.037 mm
(0.0004–0.0015 in)
Exhaust:
0.025–0.052 mm
(0.0010–0.0020 in)

Replacing the valve guides

1. Remove the valve guide 1 by striking
the special service tool from the combus-
tion chamber side.
Valve guide remover/installer:
90890-06801
2. Install the new valve guide 2 by striking
the special service tool from the rocker
arm side until the valve guide reaches
the specified installation position a.
2
5-17
Power unit
1
S69M5360
b
a
2
E
S69M5370
NOTE:
• Before installing the valve guide, mark its
installation position b as shown.
• Apply engine oil to the new valve guide.
Valve guide installation position a:
5.9 mm (0.23 in)
Valve guide remover/installer:
90890-06801
3. Insert the special service tool into the
valve guide 2, and then ream the valve
guide.
2
NOTE:
• Turn the valve guide reamer clockwise to
ream the valve guide.
• Do not turn the reamer counterclockwise
when removing the reamer.
Valve guide reamer: 90890-06804
4. Measure the valve guide inside diameter.
Replace the valve guide if out of specifi-
cation.
Valve guide inside diameter:
5.500–5.512 mm
(0.2165–0.2170 in)
S69M5380
69M3E11