2003 YAMAHA WR 450F engine

4 - 81
ENG

5. Install:

Bolt (starter clutch)
1


Plain washer (rotor)

Nut (rotor)
2

NOTE:

Tighten the rotor nut to 65 Nm (6.5 m·kg,
47 ft·lb), loosen and retighten the rotor nut to
65 Nm (6.5 m·kg, 47 ft·lb).
6. Install:

Shaft
1


Bearing
2


Idle gear 2
3

NOTE:

Apply the engine oil on the shaft, bearing and
idle gear inner circumference.
T R..16 Nm (1.6 m · kg, 11 ft · lb)
T R..65 Nm (6.5 m · kg, 47 ft · lb)

7. Install:

Dowel pin

Gasket [crankcase cover (left)]

Crankcase cover (left)
1


Bolt [crankcase cover (left)]
NOTE:

Tighten the bolts in stage, using a crisscross
pattern.
New
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

8. Install:

Shaft
1


Bearing
2


Idle gear 1
3

NOTE:

Apply the engine oil on the shaft, bearing and
idle gear inner circumference.
9. Install:

Cover (idle gear 1)
1


Bolt
2

NOTE:

Install the cover (idle gear 1) with its mark
a
facing upward.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

AC MAGNETO AND STARTER CLUTCH

4 - 82
ENG
10. Install:
Engine guard 1
Clamp 2
Bolt [engine guard (front)] 3
Bolt [engine guard (rear)] 4
Cylinder head breather hose 5
T R..34 Nm (3.4 m · kg, 24 ft · lb)
T R..23 Nm (2.3 m · kg, 17 ft · lb)
11. Connect:
AC magneto lead
Refer to “CABLE ROUTING DIA-
GRAM” section in the CHAPTER 2.
12. Install:
Shift pedal 1
Bolt (shift pedal)
NOTE:
When installing the shift pedal onto the shift
shaft, be sure that the center of the shift pedal
is about 1 mm (0.04 in) a above the top of the
footrest.
T R..12 Nm (1.2 m · kg, 8.7 ft · lb)
AC MAGNETO AND STARTER CLUTCH

4 - 83
ENGENGINE REMOVAL
EC4M0000
ENGINE REMOVAL
Extent of removal Order Part name Q’ty Remarks
ENGINE REMOVAL
Preparation for removal Hold the machine by placing the
suitable stand under the frame.
WARNING
Support the machine securely so there is no
danger of it falling over.
Drain the engine oil Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Carburetor Refer to “CARBURETOR” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Clutch cable and guide Disconnect at the engine side.
Radiator Refer to “RADIATOR” section.
Shift pedal Refer to “AC MAGNETO AND
STARTER CLUTCH” section.
Cylinder head breather hose and
oil tank breather hoseRefer to “CAMSHAFTS” section.
Ignition coil
Disconnect the AC magneto lead.

4 - 84
ENGENGINE REMOVAL
Extent of removal:1 Engine removal
Extent of removal Order Part name Q’ty Remarks
Crankcase cover (left) Refer to “AC MAGNETO AND
STARTER CLUTCH” section for remov-
ing the starter motor lead.
Disconnect the starter motor
lead.Refer to “ELECTRIC STARTING SYS-
TEM” section in the CHAPTER 6.
Negative battery lead Disconnect at the starter motor side.
1 Engine skid plate (front) 1
2 Neutral switch 1
3 Oil hose 2
4 Chain cover 1
5 Nut (drive sprocket) 1
Refer to “REMOVAL POINTS”. 6 Lock washer 1
7 Drive sprocket 1
8 Clip 1
9 Bolt (brake pedal) 1
10 Brake pedal 1
1

4 - 85
ENGENGINE REMOVAL
Extent of removal Order Part name Q’ty Remarks
11 Engine upper bracket (right) 1
12 Engine upper bracket (left) 1
13 Engine lower bracket 2
14 Engine mounting bolt 3
15 Pivot shaft 1
Refer to “REMOVAL POINTS”.
16Engine
1
1

4 - 86
ENGENGINE REMOVAL
EC4M3000
REMOVAL POINTS
EC4F3100
Drive sprocket
1. Remove:
Nut (drive sprocket) 1
Lock washer 2
NOTE:
Straighten the lock washer tab.
Loosen the nut while applying the rear brake.
2. Remove:
Drive sprocket 1
Drive chain 2
NOTE:
Remove the drive sprocket together with the
drive chain.
EC4M3301
Engine removal
1. Remove:
Pivot shaft 1
NOTE:
If the pivot shaft is pulled all the way out, the
swingarm will come loose. If possible, insert a
shaft of similar diameter into the other side of
the swingarm to support it.
2. Remove:
Engine 1
From right side.
NOTE:
Make sure that the couplers, hoses and cables
are disconnected.
1

4 - 87
ENGENGINE REMOVAL
EC4M5000
ASSEMBLY AND INSTALLATION
Engine installation
1. Install:
Engine 1
Install the engine from right side.
Pivot shaft 2
Engine mounting bolt (lower) 3
Engine lower bracket 4
Bolt (engine bracket) 5
Engine mounting bolt (front) 6
Engine upper bracket (right) 7
Engine upper bracket (left) 8
Bolt (engine bracket) 9
Engine mounting bolt (upper) 0
Bolt (engine guard) A
Engine skid plate (front) B
Bolt (engine skid plate) C
NOTE:
Apply the molybdenum disulfide grease on the
pivot shaft.
T R..85 Nm (8.5 m · kg, 61 ft · lb)
T R..69 Nm (6.9 m · kg, 50 ft · lb)
T R..34 Nm (3.4 m · kg, 24 ft · lb)
T R..69 Nm (6.9 m · kg, 50 ft · lb)
T R..55 Nm (5.5 m · kg, 40 ft · lb)
T R..55 Nm (5.5 m · kg, 40 ft · lb)
T R..23 Nm (2.3 m · kg, 17 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
EC4M5211
Brake pedal
1. Install:
Spring
Brake pedal 1
O-ring 2
Bolt (brake pedal) 3
Clip 4
NOTE:
Apply the lithium soap base grease on the
bolt, O-rings and brake pedal bracket.
Install the clip with its stopper portion a fac-
ing inward.
New
T R..26 Nm (2.6 m · kg, 19 ft · lb)

4 - 88
ENGENGINE REMOVAL
Drive sprocket
1. Install:
Drive sprocket 1
Drive chain 2
NOTE:
Install the drive sprocket together with the
drive chain.
2. Install:
Lock washer 1
Nut (drive sprocket) 2
NOTE:
Tighten the nut while applying the rear brake.
New
T R..75 Nm (7.5 m · kg, 54 ft · lb)
3. Bend the lock washer tab to lock the nut.
4. Install:
Chain guide
Chain cover 1
Screw (chain cover) 2
5. Install:
O-ring 1
Dowel pin 2
Oil hose 3
Bolt (oil hose) 4
NOTE:
Apply the lithium soap base grease on the O-
ring.
6. Install:
Spring 1
Pin 2
O-ring 3
Neutral switch 4
Screw (neutral switch) 5
NOTE:
Apply the lithium soap base grease on the O-
ring.
21T R..8 Nm (0.8 m · kg, 5.8 ft · lb)
New
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
New
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)