Yamaha YFZ450S 2003 Service Manual page 174

VALVES AND VALVE SPRINGS
f. Apply Mechanic's blueing dye (Dykem) to
g. Install the valve into the cylinder head.
h. Press the valve through the valve guide and
i. Measure the valve seat width again. If the
L
10.Measure:
11.Measure:
b Installed length
4 - 31
the valve face.
onto the valve seat to make a clear pattern.
valve seat width is out of specification,
reface and relap the valve seat.
LLL L LLL L L LLL L L LLL
• 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)
• compressed valve spring force a
Out of specification → Replace.
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)
ENG
L L LLL L L LLL L LLL