Checking The Valve Guides; Replacing The Valve Guides - Yamaha F50F Service Manual

POWR
3. Measure the valve stem diameter b.
Replace if out of specification.
Valve stem diameter b:
Intake:
5.475–5.490 mm
(0.2156–0.2161 in)
Exhaust:
5.460–5.475 mm
(0.2150–0.2156 in)
4. Measure the valve stem runout. Replace
if above specification.
Valve stem runout limit:
Intake: 0.05 mm (0.0020 in)
Exhaust: 0.03 mm (0.0012 in)

Checking the valve guides

NOTE:
Before checking the valve guide make sure
that the valve stem diameter is within specifi-
cation.
1. Measure the valve guide inside diameter
a.
5-25
Power unit
Valve guide inside diameter a:
Intake and exhaust:
5.500–5.512 mm
(0.2165–0.2170 in)
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 and 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 end.
Valve guide remover/installer:
90890-06801
2. Install a new valve guide by striking the
special service tool from the camshaft
end.
6C13G11