Yamaha TT-R90(V), Owner'S Service Manual

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ENG
VALVES AND VALVE SPRINGS
Valve spring
1. Measure:
• Valve spring free length
a
Out of specification
→
Replace.
2. Measure:
• Spring tilt
a
Out of specification
→
Replace.
Free length (valve spring):
Intake:
32.45 mm (1.28 in)
<Limit>: 26.9 mm (1.06 in)
Exhaust:
32.45 mm (1.28 in)
<Limit>: 26.9 mm (1.06 in)
Spring tilt limit:
Intake:
2.5°/1.4 mm (0.06 in)
Exhaust:
2.5°/1.4 mm (0.06 in)
Valve seat
1. Measure:
• Valve seat width
a
Out of specification
→
Reface the valve
seat.
Valve seat width:
Intake:
0.9 ~ 1.1 mm (0.0354 ~ 0.0433 in)
<Limit>: 1.6 mm (0.0630 in)
Exhaust:
0.9 ~ 1.1 mm (0.0354 ~ 0.0433 in)
<Limit>: 1.6 mm (0.0630 in)
Measurement steps:
• Apply Mechanic’s blueing dye (Dykem)
b
to the valve face.
• Install the valve into the cylinder head.
• Press the valve through the valve guide
and onto the valve seat to make a clear
pattern.
• Measure the valve seat width. Where the
valve seat and valve face made contact,
blueing will have been removed.
• If the valve seat is too wide, too narrow, or
the seat is not centered, the valve seat
must be refaced.