Yamaha YZ 2019 Series, Owner'S Service Manual

Page: 214 / 398

CAMSHAFT
5-15
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5. Measure:
• Camshaft journal diameter “a”
Out of specification

Replace the camshaft.
Within specification

Replace the cylinder
head and the camshaft caps as a set.
EAM30082
CHECKING THE TIMING CHAIN AND
CAMSHAFT SPROCKET
1. Check:
•
Timing chain
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.
EAM30083
CHECKING THE TIMING CHAIN
TENSIONERS
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.
c. If not, replace the tensioner assembly.
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Camshaft journal diameter
21.959–21.972 mm (0.8645–
0.8650 in)
1
a. 1/4 tooth
b. Correct
1. Timing chain roller
2. Camshaft sprocket
a
b
1
2