Installing The Cylinder Head - Yamaha YZ450FX 2019 Owner's Service Manual

EAM30089

INSTALLING THE CYLINDER HEAD

1. Install:
• Timing chain guide (intake side) "1"
• Dowel pin "2"
• Cylinder head gasket "3"
• Cylinder head "4"
TIP
While pulling up the timing chain, install the tim-
ing chain guide (intake side) and the cylinder
head.
3
2
1
2. Install:
• Washer "1"
• Bolt "2"
• Bolt "3"
2
M
TIP
Tighten the bolts using the following procedure.
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a. Wash the threads and contact surfaces of the
bolts, the contact surfaces of the washers,
the contact surface of the cylinder head, and
the threads of the crankcase.
b. Apply molybdenum disulfide grease to the
threads and contact surfaces of the bolts and
to both contact surfaces of the washers "1".
c. Install the washers and the bolts.
d. Tighten the bolts to the specified torque in
two or three steps in the proper tightening se-
quence as shown.
New
4
2
2
1
3
3
5-22
CYLINDER HEAD
Bolt "1"–"4"
1st
40 N·m (4.0 kgf·m, 30 lb·ft)
x2 x3 x1
3 3
5 5
6 6
1 1
e. Remove the bolts.
f. Again apply molybdenum disulfide grease to
the threads and contact surfaces of the bolts
and to both contact surfaces of the washers.
g. Retighten the bolts.
TIP
Tighten the bolts to the specified torque in two or
three steps in the proper tightening sequence as
shown.
Bolt "1"–"4"
2nd
22 N·m (2.2 kgf·m, 16 lb·ft)
h. Put a mark on the corner "1" of the bolt (cylin-
der head) and the cylinder head "2" as
shown.
FWD
2 2
4 4
1
2