2006 YAMAHA YZ450F engine

4 - 68
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 - 69
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.
T R..2 Nm (0.2 m · kg, 1.4 ft · lb)
New
4. Install:
Outer rotor 2 1
Dowel pin 2
Oil pump assembly 3
Bolt (oil pump assembly) 4
NOTE:
Apply the engine oil on the outer rotor 2.
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 - 74
ENGKICK AXLE AND SHIFT SHAFT
EC4C5000
ASSEMBLY AND INSTALLATION
Segment
1. Install:
Segment 1
Bolt (segment)
NOTE:
Align the notch a on the segment with the pin
b on the shift cam.
CAUTION:
If the segment gets an impact, it may be
damaged. Take care not to give an impact
to the segment when tightening the bolt.
T R..30 Nm (3.0 m · kg, 22 ft · lb)
EC4B5111
Stopper lever
1. Install:
Torsion spring 1
Plain washer 2
Stopper lever 3
Bolt (stopper lever) 4
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.
1
2
4
3
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
NOTE:
Apply the engine oil on the springs, pawl pins
and pawls.
2. Install:
Shift lever assembly 1
To shift guide 2.
1
2

4 - 75
ENGKICK AXLE AND SHIFT SHAFT
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)
EC4C5301
Shift shaft
1. Install:
Roller 1
Collar 2
Torsion spring 3
Plain washer 4
Shift shaft 5
NOTE:
Apply the engine oil on the roller and shift
shaft.
2. 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
4.4 mm (0.17 in) a above the top of the footrest.
T R..12 Nm (1.2 m · kg, 8.7 ft · lb)

4 - 76
ENGKICK AXLE AND SHIFT SHAFT
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.
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 ratchet wheel guide 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 ratchet wheel guide.

4 - 77
ENG
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
KICK AXLE AND SHIFT SHAFT

4 - 81
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 nodanger of it falling over.
Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Rear shock absorber Refer to “REAR SHOCK ABSORBER”
section in the CHAPTER 5.
Carburetor Refer to “CARBURETOR” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Clutch cable Disconnect at engine side.
Radiator Refer to “RADIATOR” section.
Shift pedal Refer to “KICK AXLE AND SHIFT
SHAFT” section.
Cylinder head breather hose Refer to “CAMSHAFTS” section.
Drain the engine oil Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Ignition coil
Disconnect the CDI magneto lead.
Engine guard

4 - 82
ENGENGINE REMOVAL
Extent of removal:
1 Engine removal
Extent of removal Order Part name Q’ty Remarks
1 Neutral switch 1
2 Chain cover 1
3 Nut (drive sprocket) 1
Refer to “REMOVAL POINTS”. 4 Lock washer 1
5 Drive sprocket 1
6Clip 1
7 Bolt (brake pedal) 1
8 Brake pedal 1
9 Engine upper bracket (right) 1
10 Engine upper bracket (left) 1
11 Engine lower bracket 2
12 Engine mounting bolt 3
13 Pivot shaft 1
Refer to “REMOVAL POINTS”.
14 Engine 1
1