Yamaha YZ450FY 2009 Owner's Service Manual page 126

CHECKING THE CAMSHAFT
1. Inspect:
• Cam lobe
Pitting/scratches/blue discoloration → Re-
place.
2. Measure:
• Cam lobe length "a" and "b"
Out of specification → Replace.
Cam lobes length:
Intake "a":
31.200–31.300 mm (1.2283–
1.2323 in)
<Limit>:
31.100 mm (1.2244 in)
Intake "b":
22.550–22.650 mm (0.8878–
0.8917 in)
<Limit>:
22.450 mm (0.8839 in)
Exhaust "a":
30.900–31.000 mm (1.2165–
1.2205 in)
<Limit>:
30.800 mm (1.2126 in)
Exhaust "b":
22.468–22.568 mm (0.8846–
0.8885 in)
<Limit>:
22.368 mm (0.8806 in)
3. Measure:
• Runout (camshaft)
Out of specification → Replace.
Runout (camshaft):
Less than 0.03 mm (0.0012 in)
4. Measure:
• Camshaft-to-cap clearance
Out of specification → Measure camshaft
outside diameter.
Camshaft-to-cap clearance:
0.028–0.062 mm (0.0011–0.0024 in)
<Limit>:0.08 mm (0.003 in)
Measurement steps:
a. Install the camshaft onto the cylinder head.
b. Position a strip of Plastigauge
camshaft.
c. Install the clip, dowel pins and camshaft
caps.
Bolt (camshaft cap):
10 Nm (1.0 m•kg, 7.2 ft•lb)
• Tighten the bolts (camshaft cap) in a criss-
cross pattern from innermost to outer caps.
• Do not turn the camshaft when measuring
clearance with the Plastigauge
d. Remove the camshaft caps and measure
the width of the Plastigauge
4-25
CAMSHAFTS
®
"1" onto the
®
.
®
"1".