Checking The Valve Guide; Replacing The Valve Guide - Yamaha F200B Service Manual

POWR
Valve margin thickness a:
Intake:
0.500–0.900 mm (0.0197–0.0354 in)
Exhaust:
0.900–1.300 mm (0.0354–0.0512 in)
3. Measure the valve stem diameter b.
Replace if out of specification.
b
Valve stem diameter b:
Intake:
5.477–5.492 mm (0.2156–0.2162 in)
Exhaust:
5.464–5.479 mm (0.2151–0.2157 in)
4. Measure the valve stem runout. Replace
if above specification.
Valve stem runout:
Intake and exhaust:
0.010 mm (0.0004 in)

Checking the valve guide

Before checking the valve guides, make sure
that the valve stem diameter is within specifi-
cation.
1. Measure the valve guide inside diameter
a.
7-63
Power unit
a
Valve guide inside diameter a:
Intake and exhaust:
5.504–5.522 mm (0.2167–0.2174 in)
2. Calculate the valve guide clearance as
follows. Replace the valve guide if out of
specification.
Valve guide clearance = valve guide inside
diameter – valve stem diameter:
Intake:
0.012–0.045 mm (0.0005–0.0018 in)
Exhaust:
0.025–0.058 mm (0.0010–0.0023 in)

Replacing the valve guide

Do not reuse a valve guide, always
replace it with a new one.
After replacing a valve guide, check the valve
seat contact area.
1. Remove the valve guide 1 using the
special service tool 2 from the combus-
tion chamber side.
Valve guide remover/installer 2:
90890-06801
2
1