Yamaha YZ 2020 Series, Owner'S Service Manual

Page: 211 / 376

CYLINDER HEAD
5-24
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.
2. Install:
•
Washer “1”
• Bolt “2”
•
Nut “3”
TIP
•
Tighten the bolts using the following proce-
dure.
•
Repeat steps (e) to (j) for each bolt one at a
time according to the tightening order of the
bolts.
a. Wash the threads and contact surfaces of
the bolts, the contact surfaces of the
washers, the contact surface of the cylin-
der head, and the threads of the crank-
case.
b. Apply molybdenum disulfide grease to the
threads and contact surfaces of the bolts
and to both contact surfaces of the wash-
ers “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
sequence as shown.
e. Remove the one bolt according to the
tightening order of 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
Do not remove the other bolts. Only remove the
bolts one at a time according to the tightening or-
der as shown and retighten them to the specified
tightening torque.
h. Put a mark on the corner “1” of the bolt
(cylinder head) and the cylinder head “2”
as shown.
New
1
3
4 2
2
2
2
1
M
3
(2)
Bolt “1”–“4”
1st
30 N·m (3.0 kgf·m, 22 lb·ft)
Bolt “1”, “2”, “3”, “4”
2nd
15 N·m (1.5 kgf·m, 11 lb·ft)
T
R
.
.
x2 x3 x1
FWD
1
5
6
4
2
3
1
5
6
4
2
3
T
R
.
.