2003 YAMAHA WR 450F engine

4 - 64
ENG

BALANCER
ASSEMBLY AND INSTALLATION
Balancer, balancer drive gear and balancer
driven gear
1. Install:

Balancer
1

NOTE:

When installing the balancer shaft, align the
center of the balancer shaft weight
a
along
the line connecting the centers of the crank-
shaft and balancer shaft.
2. Install:

Balancer driven gear
1

NOTE:

Install the balancer driven gear onto the bal-
ancer while aligning the punch mark
a
on the
balancer driven gear with the lower spline b
on the balancer end.
3. Install:
Balancer drive gear 1
NOTE:
Align the punched mark a on the balancer
drive gear with the punched mark b on the
balancer driven gear.
Align the punched mark c on the balancer
drive gear with the lower spline d on the
crankshaft.
4. Install:
Lock washer 1
Nut (balancer) 2
Primary drive gear 3
Nut (primary drive gear) 4
NOTE:
Install the primary drive gear with its stepped
side b facing the engine.
Place an aluminum plate a between the
teeth of the balancer drive gear 5 and
driven gear 6.
5. Bend the lock washer tab.
T R..50 Nm (5.0 m · kg, 36 ft · lb)
T R..75 Nm (7.5 m · kg, 54 ft · lb)
b3

4 - 67
ENGOIL PUMP
INSPECTION
Oil pump
1. Inspect:
Oil pump drive gear
Oil pump driven gear
Rotor housing
Oil pump cover
Cracks/wear/damage → Replace.
2. Measure:
Tip clearance a
Between the inner rotor 1 and the
outer rotor 2.
Tip clearance b
Between the outer rotor 2 and the rotor
housing 3.
Out of specification → Replace the oil
pump.
Tip clearance a:
0.12 mm or less
(0.0047 in or less)
: 0.20 mm (0.008 in)
Tip clearance b:
0.09 ~ 0.17 mm (0.0035 ~ 0.0067 in)
: 0.24 mm (0.009 in)
Side clearance c:
0.03 ~ 0.10 mm (0.0012 ~ 0.0039 in)
: 0.17 mm (0.007 in)
3. Check:
Unsmooth → Repeat steps #1 and #2
or replace the defective parts.
ASSEMBLY AND INSTALLATION
Oil pump
1. Install:
Oil pump drive shaft 1
Washer 2
Pin 3
Inner rotor 1 4
NOTE:
Apply the engine oil on the oil pump drive
shaft and inner rotor 1.
Fit the pin into the groove in the inner rotor 1.

4 - 68
ENGOIL PUMP
2. Install:
Outer rotor 1 1
NOTE:
Apply the engine oil on the outer rotor 1.
3. Install:
Oil pump cover 1
Screw (oil pump cover) 2
Pin 3
Inner rotor 2 4
Circlip 5
NOTE:
Apply the engine oil on the oil pump drive
shaft end and inner rotor 2.
Fit the pin into the groove in the inner rotor 2.
4. Install:
Outer rotor 2 1
Dowel pin 2
Oil pump assembly 3
Bolt (oil pump assembly)
[L = 30 mm (1.18 in)] 4
Bolt (oil pump assembly)
[L = 25 mm (0.98 in)] 5
NOTE:
Apply the engine oil on the outer rotor 2.
T R..2 Nm (0.2 m · kg, 1.4 ft · lb)
New
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
5. Install:
Oil pump drive gear 1
Plate washer 2
Circlip 3
NOTE:
Apply the engine oil on the oil pump drive gear
inner circumference.
New

4 - 73
ENGKICK AXLE AND SHIFT SHAFT
EC4B5111
Stopper lever
1. Install:
Torsion spring 1
Stopper lever 2
Bolt (stopper lever) 3
NOTE:
Align the stopper lever roller with the slot on
segment.
Shift guide and shift lever assembly
1. Install:
Spring 1
Pawl pin 2
Pawl 3
To shift lever 4.
NOTE:
Apply the engine oil on the springs, pawl pins
and pawls.
2. Install:
Shift lever assembly 1
To shift guide 2.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
2
1
3. Install:
Shift lever assembly 1
Shift guide 2
NOTE:
The shift lever assembly is installed at the
same time as the shift guide.
Apply the engine oil on the bolt (segment)
shaft.
4. Install:
Bolt (shift guide) 1
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

4 - 74
ENGKICK AXLE AND SHIFT SHAFT
EC4C5301
Shift shaft
1. Install:
Roller 1
Collar 2
Torsion spring 3
Shift shaft 4
NOTE:
Apply the engine oil on the roller and shift
shaft.
2. Install:
Shift pedal
Refer to “AC MAGNETO AND
STARTER CLUTCH” section.
Kick axle assembly
1. Install:
Kick gear 1
Plain washer 2
Circlip 3
Ratchet wheel 4
Spring 5
Plain washer 6
Circlip 7
To kick axle 8.
NOTE:
Apply the molybdenum disulfide oil on the
inner circumferences of the kick gear and
ratchet wheel.
Align the punch mark a on the ratchet wheel
with the punch mark b on the kick axle.
New
New
2. Install:
Torsion spring 1
To kick axle 2.
NOTE:
Make sure the stopper a of the torsion spring
fits into the hole b on the kick axle.

4 - 75
ENGKICK AXLE AND SHIFT SHAFT
3. Install:
Spring guide 1
NOTE:
Slide the spring guide into the kick axle, make
sure the groove a in the spring guide fits on
the stopper of the torsion spring.
4. Install:
Kick axle assembly 1
Plain washer 2
NOTE:
Apply the molybdenum disulfide grease on
the contacting surfaces of the kick axle stop-
per a and stopper plate 3.
Apply the engine oil on the kick axle.
Slide the kick axle assembly into the crank-
case and make sure the kick axle stopper fits
into the stopper plate.
5. Hook:
Torsion spring 1
NOTE:
Turn the torsion spring clockwise and hook
into the proper hole a in the crankcase.
Kick idle gear
1. Install:
Kick idle gear 1
Plain washer 2
Circlip 3
NOTE:
Install the kick idle gear with its depressed
side a toward you.
Apply the engine oil on the kick idle gear
inner circumference.
New

4 - 76
ENG

AC MAGNETO AND STARTER CLUTCH
AC MAGNETO AND STARTER CLUTCH
Extent of removal:
1
Starter clutch/wheel gear removal
2
Rotor removal
3
Pickup coil/stator removal
Extent of removal Order Part name Q’ty Remarks
AC MAGNETO AND STATOR
REMOVAL
Preparation for removal 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.
Bolt [radiator (left)]
Disconnect the AC magneto lead.Refer to “RADIATOR” section.
1 Shift pedal 1
2 Engine guard (left) 1
3 Cover (idle gear 1) 1
4 Idle gear 1 1
5 Bearing 1
6 Shaft 1
7 Crankcase cover (left) 1
8 Gasket 1
31

4 - 80
ENGAC MAGNETO AND STARTER CLUTCH
2. Install:
Holder 1
Bolt 2
NOTE:
Pass the pick-up coil lead 3 and AC mag-
neto lead 4 under the holder as shown.
Take care not to catch the AC magneto lead
between crankcase cover ribs.
Apply the sealant to the grommet of the AC
magneto lead.
Quick gasket:
ACC-QUICK-GS-KT
YAMAHA Bond No. 1215:
90890-85505
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
3. Install:
Plain washer 1
Bearing 2
Starter clutch drive gear 3
Starter clutch 4
NOTE:
Apply the engine oil on the plain washer, bear-
ing and starter clutch drive gear inner circum-
ference.
4. Install:
Woodruff key 1
Rotor 2
NOTE:
Clean the tapered portions of the crankshaft
and rotor.
When installing the woodruff key, make sure
that its flat surface a is in parallel with the
crankshaft center line b.
When installing the rotor, align the keyway c
of the rotor with the woodruff key.
c
2 1 1
ba