VALVES AND VALVE SPRINGS
5-21
4. Lap:
• Valve face
• Valve seat
NOTE:
After replacing the cylinder head or replacing the
valve and valve guide, the valve seat and valve
face should be lapped.
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a. Apply a coarse lapping compound “a” to the
valve face.
CAUTION:
ECA13790
Do not let the lapping compound enter the
gap between the valve stem and the valve
guide.
b. Apply molybdenum disulfide oil onto the
valve stem.
c. Install the valve into the cylinder head.
d. Turn the valve until the valve face and valve
seat are evenly polished, then clean off all of
the lapping compound.
NOTE:
For the best lapping results, lightly tap the valve
seat while rotating the valve back and forth be-
tween your hands.
e. Apply a fine lapping compound to the valve
face and repeat the above steps.
f. After every lapping procedure, be sure to
clean off all of the lapping compound from the
valve face and valve seat.
g. Apply Mechanic’s blueing dye (Dykem) “b”
onto the valve face.
h. Install the valve into the cylinder head.
i. Press the valve through the valve guide and
onto the valve seat to make a clear impres-
sion.
j. Measure the valve seat width “c” again. If the
valve seat width is out of specification, reface
and lap the valve seat.
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EAS24310
CHECKING THE VALVE SPRINGS
The following procedure applies to all of the
valve springs.
1. Measure:
• Valve spring free length “a”
Out of specification
→
Replace the valve
spring.
YamahaR125.COM
Summary of Contents for YZF-R125
Page 1: ...5D7 F8197 E0 YAMAHAR125 COM SERVICE MANUAL YZF R125 ...
Page 6: ...YamahaR125 COM ...
Page 8: ...YamahaR125 COM ...
Page 52: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 2 29 1 2 3 4 YamahaR125 COM ...
Page 70: ...CABLE ROUTING 2 47 YamahaR125 COM ...
Page 73: ...YamahaR125 COM ...
Page 102: ...ELECTRICAL SYSTEM 3 29 YamahaR125 COM ...
Page 105: ...YamahaR125 COM ...
Page 172: ...CHAIN DRIVE 4 67 YamahaR125 COM ...
Page 181: ...ENGINE REMOVAL 5 6 2 2 4 1 3 YamahaR125 COM ...
Page 263: ...THROTTLE BODY 7 8 YamahaR125 COM ...
Page 264: ...AIR INDUCTION SYSTEM 7 9 EAS27040 AIR INDUCTION SYSTEM 1 2 3 YamahaR125 COM ...
Page 268: ...AIR INDUCTION SYSTEM 7 13 YamahaR125 COM ...
Page 271: ...YamahaR125 COM ...
Page 283: ...CHARGING SYSTEM 8 12 1 AC magneto 3 Rectifier regulator 4 Main fuse 9 Battery YamahaR125 COM ...
Page 285: ...CHARGING SYSTEM 8 14 YamahaR125 COM ...
Page 295: ...SIGNALING SYSTEM 8 24 YamahaR125 COM ...
Page 299: ...COOLING SYSTEM 8 28 YamahaR125 COM ...
Page 323: ...FUEL INJECTION SYSTEM 8 52 YamahaR125 COM ...
Page 327: ...FUEL PUMP SYSTEM 8 56 YamahaR125 COM ...
Page 353: ...YamahaR125 COM ...
Page 354: ...YamahaR125 COM ...