Yamaha YZ450FP 2023, Owner'S Service Manual

Page: 210 / 388

CAMSHAFT
5-14
EAM30083
CHECKING THE TIMING CHAIN
TENSIONERS
1. Check:
• Timing chain tensioner
Crack/damage

Replace.
a. While pressing the tensioner rod lightly
with your fingers, use a thin screwdriver
“1” to wind the tensioner rod up fully clock-
wise.
b. When releasing the screwdriver by press-
ing lightly with your fingers, make sure that
the tensioner rod will come out smoothly.
c. If not, replace the tensioner assembly.
EAM30084
CHECKING THE DECOMPRESSION SYSTEM
1. Check:
•
Decompression system
a. Check that the decompressor cam “1”
moves smoothly.
b. Check that the decompressor lever pin “2”
projects from the camshaft.
EAM30085
INSTALLING THE CAMSHAFTS
1. Install:
•
Exhaust camshaft “1”
• Intake camshaft “2”
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.
b. Align the top dead center (TDC) mark “a”
on the generator rotor with the alignment
mark “b” on the crankcase cover.
a. 1/4 tooth
b. Correct
1. Timing chain roller
2. Camshaft sprocket
a
b
1
2
2
1 1 1
2 2 2 1 1
M
E
M
b b b b b
a a a a