Checking The Timing Chain And Camshaft Sprocket; Checking The Timing Chain Tensioners - Yamaha YZ450F Owner's Service Manual

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a. Install the camshaft into the cylinder head.
b. Position a strip of Plastigauge® "1" onto the
camshaft journal as shown.
c. Install the dowel pins and the camshaft
caps.
TIP
• Tighten the camshaft cap bolts in a crisscross
pattern from innermost to outer caps.
• Do not turn the camshaft when measuring the
camshaft journal-to-camshaft cap clearance.
Camshaft cap bolts
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
d. Remove the camshaft caps and then mea-
sure the width of the Plastigauge® "1".
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5. Measure:
• Camshaft journal diameter "a"
Out of specification  Replace the cam-
shaft.
Within specification  Replace the cylinder
head and the camshaft caps as a set.
Camshaft journal diameter
21.959–21.972 mm (0.8645–
0.8650 in)
1
CHECKING THE TIMING CHAIN AND CAM-
EASB111209
SHAFT SPROCKET
1. Check:
• Timing chain "1"
Damage/stiffness  Replace the timing
chain and camshaft as a set.
2. Check:
• Camshaft sprocket
More than 1/4 tooth wear "a"  Replace the
camshaft and the timing chain as a set.
a. 1/4 tooth
b. Correct
1
1. Timing chain roller
2. Camshaft sprocket
CHECKING THE TIMING CHAIN TENSION- EASB111210
ERS
1. Check:
• Timing chain tensioner
Crack/damage  Replace.
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a. While pressing the tensioner rod lightly with
your fingers, use a thin screwdriver "1" to
wind the tensioner rod up fully clockwise.
b. When releasing the screwdriver by pressing
lightly with your fingers, make sure that the
tensioner rod will come out smoothly.
5-16
a
b
CAMSHAFT
1
2