Checking The Valve Springs - Yamaha YZ 2016 Series Owner's Service Manual

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 contact width "c"
again. If the valve seat contact width is out of
specification, reface and lap the valve seat.
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EASB296227

CHECKING THE VALVE SPRINGS

1. Measure:
• Valve spring free length "a"
Out of specification  Replace the valve
spring.
Free length (intake)
36.69 mm (1.44 in)
Limit
34.85 mm (1.37 in)
Free length (exhaust)
34.86 mm (1.37 in)
Limit
33.11 mm (1.30 in)
VALVES AND VALVE SPRINGS
2. Measure:
• Compressed valve spring force "a"
Out of specification  Replace the valve
spring.
b. Installed length
Installed compression spring
force (intake)
146.00–168.00 N (14.89–17.13
kgf, 32.82–37.77 lbf)
Installed compression spring
force (exhaust)
137.00–157.00 N (13.97–16.01
kgf, 30.80–35.29 lbf)
Installed length (intake)
31.40 mm (1.24 in)
Installed length (exhaust)
28.50 mm (1.12 in)
3. Measure:
• Valve spring tilt "a"
Out of specification  Replace the valve
spring.
Spring tilt (intake)
1.6 mm (0.06 in)
Spring tilt (exhaust)
1.5 mm (0.06 in)
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