Checking The Valve Springs; Checking The Valve Lifters - Yamaha YZ450F(E) 2014 Owner's Service Manual

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EAS1SL1223

CHECKING THE VALVE SPRINGS

1. Measure:
• Valve spring free length "a"
Out of specification  Replace the valve
spring.
Free length (intake)
40.76 mm (1.60 in)
Limit
39.76 mm (1.57 in)
Free length (exhaust)
37.01 mm (1.46 in)
Limit
36.01 mm (1.42 in)
2. Measure:
• Compressed valve spring force "a"
Out of specification  Replace the valve
spring.
b. Installed length
VALVES AND VALVE SPRINGS
Installed compression spring
force (intake)
178.00–204.00 N (18.15–20.80
kgf, 40.01–45.86 lbf)
Installed compression spring
force (exhaust)
124.00–142.00 N (12.64–14.48
kgf, 27.88–31.92 lbf)
Installed length (intake)
34.78 mm (1.37 in)
Installed length (exhaust)
30.83 mm (1.21 in)
3. Measure:
• Valve spring tilt "a"
Out of specification  Replace the valve
spring.
Spring tilt (intake)
2.5 °/1.8 mm (2.5 °/0.07 in)
Spring tilt (exhaust)
2.5 °/1.6 mm (2.5 °/0.06 in)

CHECKING THE VALVE LIFTERS

EAS1SL1224
1. Check:
• Valve lifter
Damage/scratches  Replace the valve lift-
ers and cylinder head.
EAS1SL1225
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