Checking The Valve Seats - Yamaha Grizzly550 User Manual

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 D (intake)
0.80–1.20 mm (0.0315–0.0472 in)
Limit
0.4 mm (0.02 in)
Valve margin thickness D (ex-
haust)
0.80–1.20 mm (0.0315–0.0472 in)
Limit
0.4 mm (0.02 in)
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 re-
place the valve stem seal.
Valve stem runout
0.040 mm (0.0016 in)
VALVES AND VALVE SPRINGS
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 C "a"
Out of specification → Replace the cylinder
head.
Valve seat width C (intake)
1.00–1.20 mm (0.0394–0.0472 in)
Limit
1.60 mm (0.0630 in)
Valve seat width C (exhaust)
1.00–1.20 mm (0.0394–0.0472 in)
Limit
1.60 mm (0.0630 in)
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a. Apply Mechanic's blueing dye (Dykem) "b"
onto the valve face.
b. Install the valve into the cylinder head.
c. Press the valve through the valve guide and
onto the valve seat to make a clear impres-
sion.
d. Measure the valve seat width.
5-24
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