Checking The Valve Seats - Yamaha YZFR6X(C) 2008 Service Manual

Valve guide remover (ø4.5)
90890-04116
Valve guide remover (4.5 mm)
YM-04116
Valve guide installer (ø4.5)
90890-04117
Valve guide installer (4.5 mm)
YM-04117
Valve guide reamer (ø4.5)
90890-04118
Valve guide reamer (4.5 mm)
YM-04118
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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 D "a"
Out of specification → Replace the valve.
Valve margin
(intake)
0.90–1.10 mm (0.0354–0.0433
in)
Limit
0.8 mm (0.03 in)
Valve margin
(exhaust)
1.10–1.30 mm (0.0433–0.0512
in)
Limit
1.0 mm (0.04 in)
6. Measure:
• Valve stem runout
Out of specification → Replace the valve.
VALVES AND VALVE SPRINGS
NOTE:
• When installing a new valve, always replace
• If the valve is removed or replaced, always
EAS24300

CHECKING THE VALVE SEATS

The following procedure applies to all of the
valves and valve seats.
1. Eliminate:
2. Check:
thickness D
3. Measure:
thickness D
5-21
the valve guide.
replace the valve stem seal.
Valve stem runout
0.040 mm (0.0016 in)
• Carbon deposits
(from the valve face and valve seat)
• Valve seat
Pitting/wear → Replace the cylinder
head.
• Valve seat width C "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)
1.10–1.30 mm (0.0433–0.0512
in)
Limit
1.8 mm (0.07 in)