2015 YAMAHA YZ450F oil

SWINGARM
4-60
EAS1SL5185
SWINGARM
Removing the swingarm
Order Part name Q’ty Remarks
Use a suitable stand to raise the front wheel
off the ground.
Brake hose holder Refer to “REAR BRAKE” on page 4-21.
Rear brake caliper Refer to “REAR BRAKE” on page 4-21.
Bolt (brake pedal)
Drive chain
1Collars 2
2Oil seals 2
3Thrust bearing 2
4Bushing 2
5Oil seals 2
6 Bearing 4
For installation, reverse the removal proce-
dure.
1
2
3
6
4
6
4
1
3
6
2
5
T.R.70 Nm (7.0 mlbf) kgf, 51 ft
T.R.4.0 Nm (0.40 mlbf) kgf, 2.9 ft

SWINGARM
4-61
EAS1SL5186REMOVING THE SWINGARM
1. Use a suitable stand to raise the rear wheel
off the ground.
EWA13120
WARNING
Securely support the vehicle so that there is
no danger of it falling over.
2. Measure:
• Swingarm side play
• Swingarm vertical movement
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a. Measure the tightening torque of the pivot
shaft nut.
b. Measure the swingarm side play “a” by mov-
ing the swingarm from side to side.
c. If the swingarm side play is out of specifica-
tion, check the spacers, the bearings, and
the collars.
d. Check the swingarm vertical movement “b”
by moving the swingarm up and down.
If swingarm vertical movement is not smooth
or if there is binding, check the spacers, the
bearings, and the collars.
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EAS1SL5187REMOVING THE BEARING
1. Remove:
• Bearing “1”
TIP
Remove the bearing by pressing its outer race.
EAS1SL5188CHECKING THE SWINGARM
1. Check:
• Swingarm
Bends/cracks/damage  Replace.
2. Check:
• Pivot shaft
Roll the pivot shaft on a flat surface.
Bends  Replace.
EWA13770
WARNING
Do not attempt to straighten a bent pivot
shaft.
3. Wash with kerosene:
• Pivot shaft
• Spacers
•Collars
• Bearing
4. Check:
• Oil seals
Damage  Replace.
• Bearing
• Spacers
Free play exists/unsmooth revolution/rust 
Replace bearing and bushing as a set. Pivot shaft nut
85 Nm (8.5 m·kgf, 61 ft·lbf)
Swingarm end free play limit (ra-
dial)
1.0 mm (0.04 in)
T R..

SWINGARM
4-62
EAS1SL5189INSTALLING THE SWINGARM
1. Lubricate:
• Bearing
•Collars
• Spacers
• Oil seal
• Pivot shaft
2. Install:
• Bearing “1”
• Oil seals “2”
(to the swingarm)
TIP
First install the outer and then the inner bear-
ings to a specified depth from inside.
3. Install:
• Swingarm
TIP
Install the pivot shaft from the right.
4. Install:
• Rear wheel
Refer to “REAR WHEEL” on page 4-7.
5. Adjust:
• Drive chain slack
Refer to “ADJUSTING THE DRIVE CHAIN
SLACK” on page 3-27.Recommended lubricant
Molybdenum disulfide grease
Installed depth “a”
0–0.5 mm (0–0.02 in)
Installed depth “b”
6.5 mm (0.26 in)
Pivot shaft nut
85 Nm (8.5 m·kgf, 61 ft·lbf)
Drive chain slack
50–60 mm (1.97–2.36 in)
New
New
2 22
1 1
aaa
b ba
NewNewNew
T R..

CLUTCH......................................................................................................... 5-37
REMOVING THE CLUTCH ...................................................................... 5-40
CHECKING THE FRICTION PLATES...................................................... 5-40
CHECKING THE CLUTCH PLATES ........................................................ 5-40
CHECKING THE CLUTCH SPRINGS...................................................... 5-40
CHECKING THE CLUTCH HOUSING ..................................................... 5-41
CHECKING THE CLUTCH BOSS ............................................................ 5-41
CHECKING THE PRESSURE PLATE ..................................................... 5-41
CHECKING THE PUSH LEVER SHAFT .................................................. 5-41
CHECKING THE CLUTCH PUSH RODS ................................................ 5-41
CHECKING THE PRIMARY DRIVE GEAR .............................................. 5-41
CHECKING THE PRIMARY DRIVEN GEAR ........................................... 5-42
INSTALLING THE OIL SEAL................................................................... 5-42
INSTALLING THE RIGHT CRANKCASE COVER ................................... 5-42
INSTALLING THE CLUTCH ..................................................................... 5-42
INSTALLING THE KICKSTARTER LEVER ............................................. 5-45
KICKSTATER................................................................................................. 5-46
REMOVING THE KICK SHAFT ASSEMBLY ........................................... 5-47
CHECKING THE KICK SHAFT AND RATCHET WHEEL ........................ 5-47
CHECKING THE KICK GEAR, KICK IDLE GEAR
AND RATCHET WHEEL ......................................................................... 5-47
INSTALLING THE KICK SHAFT ASSEMBLY .......................................... 5-47
INSTALLING THE KICK IDLE GEAR ....................................................... 5-48
SHIFT SHAFT................................................................................................. 5-49
REMOVING THE SHIFT GUIDE AND SHIFT LEVER ASSEMBLY ......... 5-51
REMOVING THE SEGMENT ................................................................... 5-51
CHECKING THE SHIFT SHAFT .............................................................. 5-51
CHECKING THE SHIFT GUIDE AND SHIFT LEVER ASSEMBLY ......... 5-51
CHECKING THE STOPPER LEVER ....................................................... 5-51
INSTALLING THE STOPPER LEVER ..................................................... 5-52
INSTALLING THE SEGMENT.................................................................. 5-52
INSTALLING THE SHIFT GUIDE AND SHIFT LEVER ASSEMBLY ....... 5-52
INSTALLING THE SHIFT SHAFT ............................................................ 5-53
INSTALLING THE SHIFT PEDAL ............................................................ 5-53
OIL PUMP AND BALANCER GEAR............................................................. 5-54
REMOVING THE BALANCER ................................................................. 5-56
CHECKING THE PRIMARY DRIVE GEAR, BALANCER SHAFT
DRIVE GEAR, AND BALANCER WEIGHT GEAR .................................. 5-56
CHECKING THE BALANCER .................................................................. 5-56
CHECKING THE OIL PUMP .................................................................... 5-56
ASSEMBLING THE OIL PUMP ................................................................ 5-57
INSTALLING THE OIL PUMP AND BALANCER GEAR .......................... 5-57

AC MAGNETO................................................................................................ 5-59
REMOVING THE AC MAGNETO............................................................. 5-60
CHECKING THE AC MAGNETO ............................................................. 5-60
CHECKING THE WOODRUFF KEY ........................................................ 5-60
INSTALLING THE AC MAGNETO ........................................................... 5-60
CRANKCASE................................................................................................. 5-62
DISASSEMBLING THE CRANKCASE..................................................... 5-65
REMOVING THE CRANKCASE BEARING ............................................. 5-65
CHECKING THE TIMING CHAIN, TIMING CHAIN GUIDE,
OIL STRAINER ........................................................................................ 5-65
CHECKING THE CRANKCASE ............................................................... 5-65
ASSEMBLING THE CRANKCASE........................................................... 5-66
CRANKSHAFT ASSEMBLY AND BALANCER SHAFT............................... 5-67
REMOVING THE BALANCER SHAFT..................................................... 5-68
REMOVING THE CRANKSHAFT ASSEMBLY ........................................ 5-68
CHECKING THE CRANKSHAFT ASSEMBLY......................................... 5-68
INSTALLING THE CRANKSHAFT ASSEMBLY....................................... 5-69
TRANSMISSION............................................................................................. 5-70
REMOVING THE TRANSMISSION ......................................................... 5-71
CHECKING THE SHIFT FORKS.............................................................. 5-71
CHECKING THE SHIFT DRUM ASSEMBLY ........................................... 5-72
CHECKING THE TRANSMISSION .......................................................... 5-72
INSTALLING THE TRANSMISSION ........................................................ 5-72

ENGINE REMOVAL
5-3
Removing the electronic parts
Order Part name Q’ty Remarks
Use a suitable stand to raise the front wheel
off the ground.
Seat Refer to “GENERAL CHASSIS” on page 4-1.
Side cover (left/right) Refer to “GENERAL CHASSIS” on page 4-1.
Air scoop (left / right) Refer to “GENERAL CHASSIS” on page 4-1.
Fuel tank Refer to “FUEL TANK” on page 7-1.
Air filter case cover
1 Rectifier/regulator 1
2ECU 1
3 Ignition coil 1
4 Condenser 1
5 Neutral switch 1
6 AC magneto coupler 1 Disconnect.
7 Crankshaft position sensor coupler 1 Disconnect.
8 Coolant temperature sensor coupler 1 Disconnect.
For installation, reverse the removal proce-
dure.
T.R.
T.R.
T.R.T.R.
8 3
7
6
154
2
LT

CAMSHAFT
5-16
EAS1SL5213CHECKING THE DECOMPRESSION SYS-
TEM
1. Check:
• Decompression system
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a. Check that the decompressor cam “1”
moves smoothly.
b. Check that the decompressor lever pin “2”
projects from the camshaft.
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EAS1SL5214INSTALLING THE CAMSHAFTS
1. Install:
• Exhaust camshaft “1”
• Intake camshaft “2”
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a. Turn the crankshaft counterclockwise with a
wrench.
TIP
• Apply molybdenum disulfide oil to the cam-
shafts.
• Apply the engine oil on the decompression
system.
• Fill the cylinder head with engine oil up to the
tops “a” of the valve lifters.b. Align the top dead center (TDC) mark “a” on
the rotor with the alignment mark “b” on the
crankcase cover.
c. Fit the timing chain “3” onto both camshaft
sprockets and install the camshafts on the
cylinder head.
TIP
Make sure that the alignment mark “c” on the
exhaust camshaft sprocket and the alignment
mark “d” on the intake camshaft sprocket are
aligned with the edge of the cylinder head.
ECA33DD029
NOTICE
Do not turn the crankshaft during the cam-
shaft installation. Damage or improper
valve timing will result.
d. Install the clips, the camshaft caps and the
bolts (camshaft cap).
1
2
Bolt (camshaft cap)
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
a
aa
b
a
c 3
d
T R..

CYLINDER HEAD
5-19
EAS1SL5215
CYLINDER HEAD
Removing the cylinder head
Order Part name Q’ty Remarks
Seat Refer to “GENERAL CHASSIS” on page 4-1.
Side cover (left/right) Refer to “GENERAL CHASSIS” on page 4-1.
Air scoop (left / right) Refer to “GENERAL CHASSIS” on page 4-1.
Fuel tank Refer to “FUEL TANK” on page 7-1.
Exhaust pipe and silencer Refer to “ENGINE REMOVAL” on page 5-1.
Radiator hose Disconnect.
Coolant temperature sensor coupler Disconnect.
Throttle body Refer to “THROTTLE BODY” on page 7-5.
Camshaft Refer to “CAMSHAFT” on page 5-11.
Upper engine bracket Refer to “ENGINE REMOVAL” on page 5-1.
1 Bolt (cylinder head) 2
2 Bolt (cylinder head) 4
3 Cylinder head 1
4 Cylinder head gasket 1
5 Timing chain guide (intake side) 1
6 Oil check bolt 2
7 66
1st
2nd
Final20 Nm (2.0 m
kgf, 14 ftIbf)T.
R.
30 Nm (3.0 mkgf, 22 ftIbf)
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
15 Nm (1.5 mkgf, 11 ftIbf)T.R.