2007 YAMAHA YZ450F fuel

4 - 2
ENG
REMOVAL POINTS
Side cover
1. Remove:
Bolt (side cover)
Side cover (left) 1
Side cover (right) 2
NOTE:
Draw the side cover downward to remove it
because its claws a are inserted in the air fil-
ter case.
Number plate
1. Remove:
Bolt (number plate)
Number plate 1
NOTE:
The projection a is inserted into the band of
the number plate. Pull the band off the pro-
jection before removal.
Remove the hot starter cable 2 and clutch
cable 3 from the cable guide b on the num-
ber plate.
The projection c on the under bracket is
inserted into the number plate. Remove the
number plate by pulling it off the projection.
ASSEMBLY AND INSTALLATION
Air scoop
1. Install:
Air scoop 1
Bolt (air scoop)
NOTE:
Put the portion a of the flap of the air filter
case on the inside of the air scoop.
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
SEAT, FUEL TANK AND SIDE COVERS

4 - 3
ENGEXHAUST PIPE AND SILENCER
EC4S0000
EXHAUST PIPE AND SILENCER
Extent of removal:
1 Silencer removal
2 Exhaust pipe removal
Extent of removal Order Part name Q’ty Remarks
EXHAUST PIPE AND
SILENCER REMOVAL
Preparation for removal Side cover (right) Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
1 Bolt (clamp) 1 Only loosening.
2 Bolt [silencer (front)] 1
3 Bolt [silencer (rear)] 1
4 Collar 1
5 Silencer 1
6Clamp 1
7 Nut (exhaust pipe) 1
8 Bolt (exhaust pipe) 1
9 Exhaust pipe 1
10 Gasket 2
2
1
2

4 - 6
ENGRADIATOR
EC450001
RADIATOR
Extent of removal:
1 Radiator removal
Extent of removal Order Part name Q’ty Remarks
RADIATOR REMOVAL
Preparation for removal Drain the coolant. Refer to “COOLANT REPLACEMENT”
section in the CHAPTER 3.
Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Exhaust pipe Refer to “EXHAUST PIPE AND
SILENCER” section.
1 Panel 2
2Clamp 8
3 Radiator (right) 1
4 Hose 2 1
5 Hose 3 1
6 Hose 4 1
7 Pipe 2/O-ring 1/1
8 Radiator breather hose 1
9 Radiator (left) 1
10 Hose 1 1
11 Pipe 1/O-ring 1/1
1

4 - 9
ENGCARBURETOR
CARBURETOR
Extent of removal:
1 Carburetor removal
Extent of removal Order Part name Q’ty Remarks
CARBURETOR REMOVAL
Preparation for removal Fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Rear shock absorber Refer to “REAR SHOCK ABSORBER”
section in the CHAPTER 5.
1Band 1
2 TPS coupler 1
3 Throttle cable cover 1
4 Throttle cable 2
5 Clamp (air cleaner joint) 1 Loosen the screw (air cleaner joint).
6 Clamp (carburetor joint) 1 Loosen the screws (carburetor joint).
7 Hot starter plunger 1
8 Carburetor 1
9 Carburetor joint 1
1

4 - 12
ENGCARBURETOR
EC466020
HANDLING NOTE
CAUTION:
Do not loosen the screws {TPS (throttle
position sensor)}
1 except when changing
the TPS (throttle position sensor) due to
failure because it will cause a drop in
engine performance.
1
REMOVAL POINTS
Pilot screw
1. Remove:
Pilot screw 1
NOTE:
To optimize the fuel flow at a small throttle
opening, each machine’s pilot screw has been
individually set at the factory. Before removing
the pilot screw, turn it in fully and count the
number of turns. Record this number as the
factory-set number of turns out.
INSPECTION
Carburetor
1. Inspect:
Carburetor body
Contamination → Clean.
NOTE:
Use a petroleum based solvent for cleaning.
Blow out all passages and jets with com-
pressed air.
Never use a wire.

4 - 22
ENGCAMSHAFTS
CAMSHAFTS
CYLINDER HEAD COVER
Extent of removal:
1 Cylinder head cover removal
Extent of removal Order Part name Q’ty Remarks
Preparation for removalCYLINDER HEAD COVER
REMOVAL
Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Hot starter plunger Refer to “CARBURETOR” section.
Engine upper bracket (right) Refer to “ENGINE REMOVAL” section.
Engine upper bracket (left)
1 Spark plug 1
2 Cylinder head breather hose 1
3 Bolt (cylinder head cover) 2
4 Cylinder head cover 1
5 Gasket 1
6 Timing chain guide (top) 1
1

4 - 30
ENGCYLINDER HEAD
CYLINDER HEAD
CYLINDER HEAD
Extent of removal:
1 Cylinder head removal
NOTE:
Tighten the cylinder head bolts to 30 Nm (3.0 m  kg, 22 ft  lb) in the proper tightening sequence, remove and
retighten the cylinder head bolts to 20 Nm (2.0 m  kg, 14 ft  lb) in the proper tightening sequence, and then
tighten the cylinder head bolts further to reach the specified angle 180° in the proper tightening sequence.
Extent of removal Order Part name Q’ty Remarks
CYLINDER HEAD REMOVAL
Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Radiator Refer to “RADIATOR” section.
Carburetor Refer to “CARBURETOR” section.
Camshaft Refer to “CAMSHAFTS” section.
1Bolt 2
2* Bolt 4 Refer to NOTE.
3 Cylinder head 1
4 Gasket 1
5 Dowel pin 2
6 Timing chain guide (front) 1
1

4 - 78
ENGCDI MAGNETO
EC4L0000
CDI MAGNETO
Extent of removal:1 CDI magneto removal
Extent of removal Order Part name Q’ty Remarks
CDI MAGNETO REMOVAL
Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Disconnect the CDI magneto lead.
1 Crankcase cover (left) 1
2 Gasket 1
3 Dowel pin 2
4 Nut (rotor) 1 Use special tool.
Refer to “REMOVAL POINTS”.
5 Rotor 1
6 Stator 1
7 Woodruff key 1
1