Checking The Valve Seats - Yamaha 2007 XP500 Service Manual

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3. Eliminate:
Carbon deposits
G
(from the valve face and valve seat)
4. Check:
Valve face
G
Pitting/wear → Grind the valve face.
Valve stem end
G
Mushroom shape or diameter larger than the
body of the valve stem → Replace the valve.
5. Measure:
Valve margin thickness "a"
G
Out of specification → Replace the valve.
Valve margin thickness
Valve margin thickness D (intake)
0.60–0.80 mm (0.0236–0.0315 in)
Limit
0.5 mm (0.0197 in)
Valve margin thickness D (ex-
haust)
0.60–0.80 mm (0.0236–0.0315 in)
Limit
0.5 mm (0.0197 in)
6. Measure:
Valve stem runout
G
Out of specification → Replace the valve.
NOTE:
When installing a new valve, always replace
G
the valve guide.
If the valve is removed or replaced, always re-
G
VALVES AND VALVE SPRINGS
place the oil seal.
Valve stem runout
Valve stem runout
0.040 mm (0.0016 in)
EAS24300

CHECKING THE VALVE SEATS

The following procedure applies to all of the
valves and valve seats.
1. Eliminate:
Carbon deposits
G
(from the valve face and valve seat)
2. Check:
Valve seat
G
Pitting/wear → Replace the cylinder head.
3. Measure:
Valve seat width "a"
G
Out of specification → Replace the cylinder
head.
Valve seat width
Valve seat width C (intake)
0.90–1.10 mm (0.0354–0.0433 in)
Limit
1.6 mm (0.06 in)
Valve seat width C (exhaust)
0.90–1.10 mm (0.0354–0.0433 in)
Limit
1.6 mm (0.06 in)
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a. Apply Mechanic's blueing dye (Dykem) "b"
5-20