Checking The Decompression System; Installing The Camshafts - Yamaha YZ450FX 2019 Owner's Service Manual

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CHECKING THE DECOMPRESSION SYSTEM

1. Check:
• Decompression system
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a. Check that the decompressor cam "1" moves
smoothly.
b. Check that the decompressor lever pin "2"
projects from the camshaft.
2 2 2
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INSTALLING THE CAMSHAFTS

1. Install:
• Exhaust camshaft "1"
• Intake camshaft "2"
2 2 2
M
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a. Turn the crankshaft counterclockwise with a
wrench.
TIP
• Apply molybdenum disulfide oil to the cam-
shafts.
• Apply the engine oil on the decompression
system.
• Fill the cylinder head with engine oil up to the
tops "a" of the valve lifters.
a
b. Align the top dead center (TDC) mark "a" on
the rotor with the alignment mark "b" on the
crankcase cover.
1 1
c. Fit the timing chain "3" onto both camshaft
sprockets and install the camshafts on the
cylinder head.
1 1
TIP
Make sure that the alignment mark "c" on the ex-
haust camshaft sprocket and the alignment
mark "d" on the intake camshaft sprocket are
aligned with the edge of the cylinder head.
E
d
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NOTICE
Do not turn the crankshaft during the cam-
shaft installation. Damage or improper valve
timing will result.
d. Install the clips, the camshaft caps and the
bolts (camshaft cap).
5-16
CAMSHAFT
a
3
Bolt (camshaft cap)
10 N·m (1.0 kgf·m, 7.4 lb·ft)
a
b
a
c