2007 YAMAHA WR 450F engine

4 - 90
ENGENGINE REMOVAL
Extent of removal:
1 Engine removal
Extent of removal Order Part name Q’ty Remarks
Cylinder head breather hose Refer to “CAMSHAFTS” section.
Ignition coil
Disconnect the AC magneto 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 guard 1
2 Neutral switch 1
3 Chain cover 1
4 Nut (drive sprocket) 1
Refer to “REMOVAL POINTS”. 5 Lock washer 1
6 Drive sprocket 1
7Clip 1
8 Bolt (brake pedal) 1
9 Brake pedal 1
1

4 - 91
ENGENGINE REMOVAL
Extent of removal Order Part name Q’ty Remarks
10 Engine upper bracket (right) 1
11 Engine upper bracket (left) 1
12 Engine lower bracket 2
13 Engine mounting bolt 3
14 Pivot shaft 1
Refer to “REMOVAL POINTS”.
15 Engine 1
1

4 - 92
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 - 93
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 lower bracket) 5
Patch 6
Engine mounting bolt (front) 7
Engine upper bracket (right) 8
Engine upper bracket (left) 9
Bolt (engine upper bracket) 0
Engine mounting bolt (upper) A
NOTE:
Apply the molybdenum disulfide grease on
the pivot shaft.
Install the patch with the claw a facing out-
side the chassis.
T R..85 Nm (8.5 m · kg, 61 ft · lb)
T R..53 Nm (5.3 m · kg, 38 ft · lb)
T R..34 Nm (3.4 m · kg, 24 ft · lb)
T R..53 Nm (5.3 m · kg, 38 ft · lb)
T R..55 Nm (5.5 m · kg, 40 ft · lb)
T R..55 Nm (5.5 m · kg, 40 ft · lb)
Brake pedal
1. Install:
Spring 1
Brake pedal 2
O-ring 3
Bolt (brake pedal) 4
Clip 5
NOTE:
Apply the lithium soap base grease on the bolt,
O-rings and brake pedal bracket.
New
T R..26 Nm (2.6 m · kg, 19 ft · lb)

4 - 94
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
21T R..8 Nm (0.8 m · kg, 5.8 ft · lb)
5. 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.
New
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)

4 - 95
ENGCRANKCASE AND CRANKSHAFT
CRANKCASE AND CRANKSHAFT
CRANKCASE AND CRANKSHAFT
Extent of removal:
1 Crankcase separation
2 Crankshaft removal
Extent of removal Order Part name Q’ty Remarks
CRANKCASE SEPARATION
Preparation for removal Engine Refer to “ENGINE REMOVAL” section.
Piston Refer to “CYLINDER AND PISTON” sec-
tion.
Balancer Refer to “BALANCER” section.
Kick axle assembly
Refer to “KICK AXLE AND SHIFT
SHAFT” section.
Segment
Stator Refer to “AC MAGNETO AND
STARTER CLUTCH” section.
1 Timing chain guide (rear) 1
2 Timing chain 1
3 Bolt (50 mm) 7
Refer to “REMOVAL POINTS”. 4 Bolt (60 mm) 2
5 Bolt (80 mm) 3
6 Hose guide 1
7 Clutch cable holder 1
8 Crankcase (right) 1
9 Crankcase (left) 1
21

4 - 98
ENGCRANKCASE AND CRANKSHAFT
REMOVAL POINTS
Crankcase
1. Separate:
Crankcase (right)
Crankcase (left)
Separation steps:
Remove the crankcase bolts, hose guide
and clutch cable holder.
NOTE:
Loosen each bolt 1/4 of a turn at a time and
after all the bolts are loosened, remove
them.
Remove the crankcase (right).
NOTE:
Place the crankcase with its left side
downward and split it by inserting a screw-
driver tip into the splitting slit a in the
crankcase.
Lift the crankcase (right) horizontally while
lightly patting the case splitting slit and
engine mounting boss using a soft ham-
mer, and leave the crankshaft and trans-
mission with the crankcase (left).
CAUTION:
Use soft hammer to tap on the case half.
Tap only on reinforced portions of case.
Do not tap on gasket mating surface.
Work slowly and carefully. Make sure the
case halves separate evenly. If the cases
do not separate, check for a remaining
case screw or fitting. Do not force.
Remove the dowel pins and O-ring.
a
Balancer shaft
1. Remove:
Balancer shaft 1
NOTE:
Remove the balancer shaft with its flat side a
facing the crankshaft.

4 - 99
ENGCRANKCASE AND CRANKSHAFT
Crankshaft
1. Remove:
Crankshaft 1
Use the crankcase separating tool 2.
CAUTION:
Do not use a hammer to drive out the
crankshaft.
Crankcase separating tool:
YU-A9642/90890-04152
Crankshaft bearing
1. Remove:
Bearing 1
NOTE:
Remove the bearing from the crankcase by
pressing its inner race.
Do not use the removed bearing.
INSPECTION
Timing chain and timing chain guide
1. Inspect:
Timing chain
Cracks/stiff → Replace the timing chain
and camshaft sprocket as a set.
2. Inspect:
Timing chain guide
Wear/damage → Replace.
EC4N4101
Crankcase
1. Inspect:
Contacting surface a
Scratches → Replace.
Engine mounting boss b, crankcase
Cracks/damage → Replace.