YAMAHA WR 450F 2016 Owners Manual

CYLINDER AND PISTON
6-34
3. Measure:• Piston ring end gapOut of specification  Replace the piston
ring.
TIP
The oil ring expander’s end gap cannot be
measured. If the oil ring ra il’s gap is excessive,
replace all three oil rings.
EAS2GC1260CHECKING THE PISTON PIN
1. Check:
• Piston pinBlue discoloration/grooves  Replace the
piston pin and then check the lubrication
system.
2. Measure: • Piston pin outside diameter “a”
Out of specification  Replace the piston
pin. 3. Measure:
• Piston pin bore inside diameter “b”Out of specification  Replace the piston.
EAS2GC1261INSTALLING THE PISTON AND CYLINDER
1. Install:
• Oil ring expander “1”
• Lower oil ring rail “2”
• Upper oil ring rail “3”
• 2nd ring “4”
• Top ring “5”
TIP
Be sure to install the piston rings so that the
manufacturer’s marks or numbers face up.
Piston ring
Top ring
End gap (installed)0.20–0.30 mm (0.0079–0.0118 in)
Limit 0.55 mm (0.0217 in)
2nd ring End gap (installed)0.35–0.50 mm (0.0138–0.0197 in)
Limit 0.85 mm (0.0335 in)
Oil ring End gap (installed)0.20–0.50 mm (0.0079–0.0197 in)
Piston pin outside diameter 17.991–18.000 mm (0.7083–
0.7087 in)
Limit 17.971 mm (0.7075 in)
Piston pin bore inside diameter 18.004–18.015 mm (0.7088–
0.7093 in)
Limit 18.045 mm (0.7104 in)
b

CYLINDER AND PISTON
6-35
2. Install:• Piston “1”
• Piston pin “2”
• Piston pin clips “3”
TIP
• Apply molybdenum disulfide oil to the piston pin.
• Install the piston with the F mark “a” on it pointing to its intake (front) side.
• Before installing the piston pin clip, cover the crankcase opening with a cloth to prevent the
clip from falling into the crankcase.
3. Lubricate: •Piston
• Piston rings
• Cylinder
4. Offset:
• Piston ring end gap 5. Install:
• Cylinder gasket
• Dowel pin
• Cylinder
TIP
• While compressing the piston rings with one hand, install the cylinder with the other hand.
• Pass the timing chain and timing chain guide
(exhaust side) through the timing chain cavity.
a. Top ring
b. 2nd ring
c. Upper oil ring rail
d. Oil ring expander
e. Lower oil ring rail
New
1
3
2
a
3
ac
eb
d
15
Ã
15Ã
15Ã
15Ã
15Ã
Cylinder bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
New
T R..

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

ELECTRIC STARTER
6-37
Disassembling the starter motor
OrderJob/Parts to remove Q’tyRemarks
1 Starter motor front cover 1
2 Starter motor yoke 1
3 Armature assembly 1
4 Starter motor rear cover 1
5 Brush set 2
For assembly, reverse the disassembly pro-
cedure.

ELECTRIC STARTER
6-38
EAS2GC1263CHECKING THE STARTER MOTOR
1. Check:•CommutatorDirt  Clean with 600 grit sandpaper.
2. Measure: • Commutator diameter “a”Out of specification  Replace the starter
motor.
3. Measure: • Mica undercut “a”Out of specification  Scrape the mica to
the proper measurement with a hacksaw
blade that has been grounded to fit the com-
mutator.
TIP
The mica of the commutator must be undercut
to ensure proper operation of the commutator.
4. Measure: • Armature assembly resistances (commuta-
tor and insulation)
Out of specification  Replace the starter
motor.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Measure the armature assembly resistanc-
es with the pocket tester.
b. If any resistance is out of specification, re- place the starter motor.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
5. Measure:• Brush length “a”Out of specification  Replace the brush
set.
6. Measure: • Brush spring force
Out of specification  Replace the brush
set.
Limit
16.6 mm (0.65 in)
Mica undercut (depth) 1.50 mm (0.06 in)
Pocket tester90890-03112
Analog pocket tester YU-03112-C
Armature coil Commutator resistance “1” 0.0117–0.0143 
Insulation resistance “2” Above 1 M 
Limit 3.50 mm (0.14 in)
Brush spring force 3.92–5.88 N (400–600 gf, 14.11–
21.17 oz)

ELECTRIC STARTER
6-39
7. Check:• Gear teethDamage/wear  Replace the starter motor.
8. Check: • Oil sealDamage/wear  Replace the defective part
(s).
EAS2GC1264ASSEMBLING THE STARTER MOTOR
1. Install: • Brush spring “1”
• Brush “2”
TIP
Align the corner of brush terminal “a” with
groove “b” and fit them together.
2. Install:• Armature assembly “1”
Install while holding down the brush using a
thin screw driver.
ECA
NOTICE
Be careful not to damage the brush during
installation.
3. Install:• O-ring “1”
• Starter motor yoke “2”
TIP
• Install the starter motor yoke with its groove “a” facing starter motor rear cover.
• Align the match mark “b” on the starter motor
yoke with the match mark “c” on the starter
motor rear cover. 4. Install:
• Circlip “1”
•Plain washer “2”
• O-ring “3”
• Washer (starter motor front cover) “4”
• Starter motor front cover “5”
TIP
• For installation, align the projections on the
washer with the slots in the front cover.
• Align the match mark “a” on the starter motor yoke with the match mark “b” on the starter
motor front cover.
5. Install: •Bolt “1”
• O-ring “2”
TIP
Apply the lithium-soap-based grease on the O-
ring.
a
b1
1
2
2
New
c b
a
1 2
New
a
12
3
b
45
New
2
1 1

ELECTRIC STARTER
6-40
6. Install:• Starter motor “1”
• Starter motor cover “2”
• Starter motor bolt “3”
• Starter motor cover bolt “4”
TIP
Pass the AC magneto lead “5” and the starter
motor laed “6” under the left crankcase cover
“a” as shown. Starter motor bolt
12 Nm (1.2 m·kgf, 8.7 ft·lbf)
Starter motor cover bolt 12 Nm (1.2 m·kgf, 8.7 ft·lbf)
T R..
15
6
4
3
2
a

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
6-42
14 Friction plate 25 Identification color (purple)
15 Clutch plate 2 3 Thickness:1.6 mm (0.063 in)
16 Cushion spring 1
17 Clutch boss 1
18 Thrust washer 1
19 Primary driven gear 1
20 Push lever shaft 1
For installation, reverse the removal proce-
dure.
Removing the clutch
Order Part name Q’tyRemarks
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