Checking The Valve Seats - Yamaha YZF-R1B 2012 Service Manual

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TIP
After replacing the valve guide, reface the
valve seat.
Valve guide remover (ø4.5)
90890-04116
Valve guide remover (4.5 mm)
YM-04116
Valve guide remover (ø5)
90890-04097
Valve guide remover (5.0 mm)
YM-04097
Valve guide installer (ø4.5)
90890-04117
Valve guide installer (4.5 mm)
YM-04117
Valve guide installer (ø5)
90890-04098
Valve guide installer (5.0 mm)
YM-04098
Valve guide reamer (ø4.5)
90890-04118
Valve guide reamer (4.5 mm)
YM-04118
Valve guide reamer (ø5)
90890-04099
Valve guide reamer (5.0 mm)
YM-04099
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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 thickness
Valve
(intake)
1.35–1.75 mm (0.0532–0.0689
in)
Valve
(exhaust)
0.50–0.90 mm (0.0197–0.0354
in)
email: info@motomatrix.co.uk
margin thickness
margin thickness
VALVES AND VALVE SPRINGS
6. Measure:
• Valve stem runout
Out of specification → Replace the valve.
TIP
• When installing a new valve, always replace
the valve guide.
• If the valve is removed or replaced, always
replace the oil seal.
Valve stem runout limit
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:
D
• Valve seat width "a"
Out of specification → Replace the cylin-
der head.
D
5-31