Checking The Valve Seats - Yamaha Star XVS950A 2009 Service Manual

Valve guide remover (ø6)
90890-04064
Valve guide remover (6.0 mm)
YM-04064-A
Valve guide installer (ø6)
90890-04065
Valve guide installer (6.0 mm)
YM-04065-A
Valve guide reamer (ø6)
90890-04066
Valve guide reamer (6.0 mm)
YM-04066
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3. Eliminate:
• Carbon deposits
(from the valve face and valve seat)
4. Check:
• Valve face
Pitting/wear → Grind the valve face.
• Valve stem end
Mushroom shape or diameter larger than
the body of the valve stem → Replace the
valve.
5. Measure:
• Valve margin thickness "a"
Out of specification → Replace the valve.
Valve margin
(intake)
1.00 mm (0.0394 in)
Valve margin
(exhaust)
1.00 mm (0.0394 in)
6. Measure:
• Valve stem runout
Out of specification → Replace the valve.
TIP
• When installing a new valve, always replace
the valve guide.
VALVES AND VALVE SPRINGS
thickness D
thickness D
5-28
• If the valve is removed or replaced, always
replace the valve stem seal.
Valve stem runout
0.010 mm (0.0004 in)
EAS24300

CHECKING THE VALVE SEATS

The following procedure applies to all of the
valves and valve seats.
1. Eliminate:
• Carbon deposits
(from the valve face and valve seat)
2. Check:
• Valve seat
Pitting/wear → Replace the cylinder
head.
3. Measure:
• Valve seat width "a"
Out of specification → Replace the cylin-
der head.
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)