Yamaha 2003 YFZ450S, Service Manual

Page: 174 / 375

4 - 31
ENG
VALVES AND VALVE SPRINGS
f. Apply Mechanic’s blueing dye (Dykem) to
the valve face.
g. Install the valve into the cylinder head.
h. Press the valve through the valve guide and
onto the valve seat to make a clear pattern.
i. Measure the valve seat width again. If the
valve seat width is out of specification,
reface and relap the valve seat.
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10.Measure:
• valve spring free length
a
Out of specification
→
Replace.
Valve spring free length
Intake
37.03 mm (1.46 in)
<Limit>: 35.17 mm (1.38 in)
Exhaust
37.68 mm (1.48 in)
<Limit>: 35.79 mm (1.41 in)
11.Measure:
• compressed valve spring force
a
Out of specification
→
Replace.
b
Installed length
Compressed valve spring force
(installed)
Intake
111.3 ~ 127.9 N at 27.87 mm
(11.35 ~ 13.04 kg at 27.87 mm,
25.02 ~ 28.75 lb at 1.10 in)
Exhaust
127.4 ~ 146.4 N at 27.38 mm
(12.99 ~ 14.93 kg at 27.38 mm,
28.64 ~ 32.91 lb at 1.08 in)