2016 YAMAHA WR 450F engine

CAMSHAFT
6-16
EAS2GC1242CHECKING THE DECOMPRESSION SYS-
TEM
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.
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EAS2GC1243INSTALLING THE CAMSHAFTS
1. Install:• Exhaust camshaft “1”
• Intake camshaft “2”
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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.
b. Align the top dead center (TDC) mark “a” on the rotor with the alignment mark “b” on the
crankcase cover. c. Fit the timing chain “3” onto both camshaft
sprockets and install the camshafts on the
cylinder head.
TIP
Make sure that the alignment mark “c” on the
exhaust camshaft sprocket and the alignment
mark “d” on the intake camshaft sprocket are
aligned with the edge of the cylinder head.
ECA
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).
TIP
• Before installing the clips, cover the cylinder head with a clean cloth to prevent the clips
from coming off into the cylinder head cavity.
• Apply the engine oil to the threads and con- tact surfaces.
• Tighten the bolts to the specified torque in two or three steps in the proper tightening se-
quence as shown.
ECA
NOTICE
The bolts (camshaft cap) must be tightened
evenly, or damage to the cylinder head,
camshaft caps, and camshaft will result.
1
2
Bolt (camshaft cap)
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
ab
c
3
d
T R..

CYLINDER HEAD
6-18
EAS2GC1244
CYLINDER HEAD
Removing the cylinder head
OrderPart name Q’tyRemarks
Refer to “INSTALLING THE CYLINDER
HEAD” on page 6-21.
Seat Refer to “GENERAL CHASSIS” on page 5-1.
Side cover (left/right) Refer to “GENERAL CHASSIS” on page 5-1.
Air scoop (left / right) Refer to “GENERAL CHASSIS” on page 5-1.
Fuel tank Refer to “FUEL TANK” on page 8-1.
Exhaust pipe and silencer Refer to “ENGINE REMOVAL” on page 6-1.
Radiator hose Disconnect.
Coolant temperature sens or coupler Disconnect.
Throttle body Refer to “THROTTLE BODY” on page 8-7.
Camshaft Refer to “CAMSHAFT” on page 6-11.
Upper engine bracket Refer to “ENGINE REMOVAL” on page 6-1.
1 Bolt (cylinder head) 2
2 Engine ground sub-lead 1
3 Bolt (cylinder head) 4
4 Cylinder head 1
8
6
7
7
10 Nm (1.0 m kgf, 7.2 ft Ibf)T.R.
10 Nm (1.0 m kgf, 7.2 ft Ibf)T.R.
15 Nm (1.5 m kgf, 11 ft Ibf)T.R.
*
20 Nm (2.0 mkgf, 14 ftIbf)T.
R.
30 Nm (3.0 mkgf, 22 ftIbf)
2
4 3
3
5
1
1
*

CYLINDER HEAD
6-21
EAS2GC1248INSTALLING THE CYLINDER HEAD
1. Install:• Timing chain guide (intake side) “1”
• Dowel pins “2”
• Cylinder head gasket
• Dowel 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”
• Cylinder head bolt “2”
• Engine ground sub-lead “3”
• Cylinder head bolt “4”
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 wash-
ers, 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
sequence as shown. 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 se-
quence as shown.
h. Put a mark on the corner “1” of the bolt (cyl- inder head) and the cylinder head “2” as
shown.
New
1 2
2
4
3
1
3 4
2
2
4
Bolt “1”–“4”
1st
30 Nm (3.0 m·kgf, 22 ft·lbf)
Bolt “1”–“4” 2nd
20 Nm (2.0 m·kgf, 14 ft·lbf)
T R..
15
6
42
3
FWD
x2 x4
T R..
1
2

ELECTRIC STARTER
6-36
EAS2GC1262
ELECTRIC STARTER
Removing the starter motor
OrderJob/Parts to remove Q’tyRemarks
Exhaust pipe Refer to “ENGINE REMOVAL” on page 6-1.
1 Starter motor cover 1
2 Starter motor lead 1
3 Starter motor 1
For assembly, reverse the disassemble pro-
cedure.
1
12 Nm (1.2 m kgf, 8.7 ft Ibf)T.R.
2
3

CLUTCH
6-41
EAS2GC1265
CLUTCH
Removing the clutch
OrderPart name Q’tyRemarks
Engine oil Drain.
Refer to “CHANGING THE ENGINE OIL” on
page 3-17.
Brake pedal Refer to “ENGINE REMOVAL” on page 6-1.
1 Clutch cable 1 Disconnect.
2 Clutch cover 1
3 O-ring 1
4 Clutch spring 6
5 Pressure plate 1
6 Push rod 1 1
7 Circlip 1
8Washer 1
9 Bearing 1
10 Ball 1
11 Push rod 2 1
12 Friction plate 1 3
13 Clutch plate 1 4 Thickness:2.0 mm (0.079 in)
LS
New
New
New
2
3
4
5
78 9
610 11
12
12
20
1
14
16
13
15 19
18
17
T.R.
T.R.
T.R.
T.R.
LT
(2) (5) (6)

CLUTCH
6-43
Removing the right crankcase cover
OrderPart name Q’tyRemarks
Engine guard Refer to “ENGINE REMOVAL” on page 6-1.
Engine oil Drain.
Refer to “CHANGING THE ENGINE OIL” on
page 3-17.
Coolant Drain.
Refer to “CHANGING THE COOLANT” on
page 3-10.
Brake pedal Refer to “ENGINE REMOVAL” on page 6-1.
Clutch cover Refer to “CLUTCH” on page 6-41.
1 Oil filter element cover 1
2 Oil filter element 1
3 Radiator pipe 2 1
4 Kickstarter lever 1
5 Right crankcase cover 1
6 Gaskets 1
7 Dowel pin 2
8Collar 1
For installation, reverse the removal proce-
dure.
T.R.
LS
New
New
67
2
5
4
1
7
8
New
3
LS
New
New
LS
LS
NewNew
LT
LS

CLUTCH
6-46
EAS2GC1276CHECKING THE PRIMARY DRIVEN GEAR
1. Check:• Primary driven gearDamage/wear  Replace the primary drive
and primary driven gears as a set.
Excessive noise during operation  Re-
place the primary drive and primary driven
gears as a set.
EAS2GC1277INSTALLING THE OIL SEAL
1. Install: • Oil seal “1”
• Washer “2”
• Circlip “3”
TIP
• Apply the lithium-soap-based grease on the
oil seal lip.
• Install the oil seal in parallel with its manufac-
ture's marks or numbers facing inward.
EAS2GC1278INSTALLING THE RIGHT CRANKCASE
COVER
1. Install: • Dowel pin “1”
• O-rings “2”
• Collar “3”
• Gasket “4”
TIP
Apply the lithium-soap-based grease on the O-
ring.
2. Install:
• Right crankcase cover “1” • Right crankcase cover bolt “2”
TIP
• Apply the engine oil on the impeller shaft end.
• When installing the crankcase cover onto the
crankcase, make sure that the impeller shaft
end “3” aligns with the balancer end slot “4”.
• Tighten the right crankcase cover bolts in
stages and in a crisscross pattern.
EAS2GC1279INSTALLING THE CLUTCH
1. Install:
• Push lever shaft “1”
TIP
• Apply the lithium-soap-based grease on the oil seal lip.
• Before installation, apply the engine oil to the
push lever shaft sliding surface.
New
New
3
2
1
LS
New
New
1
1
4
2
New
New
3
LS
Right crankcase cover bolt10 Nm (1.0 m·kgf, 7.2 ft·lbf)
T R..
1 2
1

CLUTCH
6-47
2. Install:• Primary driven gear “1”
• Thrust washer “2”
• Clutch boss “3”
TIP
Apply the engine oil on the primary driven gear
inner circumference.
3. Install:• Conical washer “1”
• Clutch boss nut “2”
ECA1DX1020
NOTICE
Make sure to tighten to specification; other-
wise, it may damage the other part that is
fastened together.
TIP
• Install the conical washer with its convex sur-face “a” outward.
• Apply engine oil to the threads and contact surface of the clutch boss nut.
• Apply engine oil to the contact surfaces of the
conical washer.
• Use the clutch holding tool “3” to hold the
clutch boss. 4. Install:
• Friction plate 1 “1”
• Clutch plate 2 “2”
• Cushion spring “3”
• Friction plate 2 “4”
• Clutch plate 1 “5”
TIP
• Install the clutch plates and friction plates al-
ternately on the clutch boss, starting with a
friction plate and ending with a friction plate.
• From the clutch boss side, install the friction
plates in order: friction plate 1  2, friction
plate 2 (identification color: purple)  5, and
friction plate 1  1.
• From the clutch boss side, the clutch plate in order: clutch plate 2 (thickness: 1.6 mm)  3,
and clutch plate 1 (thickness: 2.0 mm)  4.
• Apply the engine oil on the friction plates and
clutch plates.
Clutch boss nut
75 Nm (7.5 m·kgf, 54 ft·lbf)
Universal clutch holder 90890-04086
Universal clutch holder YM-91042
New
T R..
a. Identification color
a2
3
21
1
314
225
1 4
5
a
4 53
4
2
1