Yamaha 5KR2, Service Manual

Page: 204 / 332

5-23
VALVES AND VALVE SPRINGS
ENG
NOTE:
5. Measure:
valve margin thickness
a
Out of specification Replace the valve.
Valve margin thickness
Intake 0.4 0.8 mm
Exhaust 0.8 1.2 mm
6. Measure:
valve stem runout
Out of specification
Replace the valve.
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
0.02 mm
EAS00240
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 cylinder
head.
Valve seat width
Intake: 0.9 1.1 mm
<Limit>: 1.6 mm
Exhaust: 0.9
1.1 mm
<Limit>: 1.6 mm
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 pattern.
d. Measure the valve seat width. Where the
valve seat and valve face contacted one
another, the blueing will have been removed.