2015 YAMAHA YZ450F Owners Manual

5
ENGINE
ENGINE REMOVAL......................................................................................... 5-1
REMOVING THE SILENCER ..................................................................... 5-6
REMOVING THE EXHAUST PIPE 2.......................................................... 5-6
REMOVING THE DRIVE SPROCKET ....................................................... 5-6
REMOVING THE ENGINE ......................................................................... 5-7
CHECKING THE SILENCER AND EXHAUST PIPE.................................. 5-7
CHANGING THE SILENCER FIBER ......................................................... 5-7
INSTALLING THE ENGINE........................................................................ 5-8
INSTALLING THE BRAKE PEDAL ............................................................ 5-9
INSTALLING THE DRIVE SPROCKET...................................................... 5-9
INSTALLING THE EXHAUST PIPE AND MUFFLER............................... 5-10
CAMSHAFT.................................................................................................... 5-11
REMOVING THE CAMSHAFT ................................................................. 5-13
CHECKING THE CAMSHAFT.................................................................. 5-14
CHECKING THE TIMING CHAIN AND CAMSHAFT SPROCKET .......... 5-15
CHECKING THE TIMING CHAIN TENSIONERS .................................... 5-15
CHECKING THE DECOMPRESSION SYSTEM...................................... 5-16
INSTALLING THE CAMSHAFTS ............................................................. 5-16
CYLINDER HEAD........................................................................................... 5-19
REMOVING THE CYLINDER HEAD........................................................ 5-21
CHECKING THE TIMING CHAIN GUIDE (INTAKE SIDE) ...................... 5-21
CHECKING THE CYLINDER HEAD ........................................................ 5-21
INSTALLING THE CYLINDER HEAD ...................................................... 5-22
VALVES AND VALVE SPRINGS................................................................... 5-24
REMOVING THE VALVES ....................................................................... 5-25
CHECKING THE VALVES AND VALVE GUIDES ................................... 5-26
CHECKING THE VALVE SEATS ............................................................. 5-27
CHECKING THE VALVE SPRINGS......................................................... 5-29
CHECKING THE VALVE LIFTERS .......................................................... 5-29
INSTALLING THE VALVES ..................................................................... 5-30
CYLINDER AND PISTON............................................................................... 5-32
REMOVING THE PISTON ....................................................................... 5-33
CHECKING THE CYLINDER AND PISTON ............................................ 5-33
CHECKING THE PISTON RINGS............................................................ 5-34
CHECKING THE PISTON PIN ................................................................. 5-35
INSTALLING THE PISTON AND CYLINDER .......................................... 5-35

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
5-1
EAS1SL5196
TIP
This section is intended for those who have basic knowledge and skill concerning the servicing of
Yamaha motorcycles (e.g., Yamaha dealers, service engineers, etc.). Those who have little knowl-
edge and skill concerning servicing are requested not to undertake inspection, adjustment, disas-
sembly, or reassembly only by reference to this manual. It may lead to servicing trouble and
mechanical damage.
EAS1SL5197
ENGINE REMOVAL
Removing the exhaust pipe
Order Part name Q’ty Remarks
Side cover (right) Refer to “GENERAL CHASSIS” on page 4-1.
Rear shock absorber assembly lower boltRefer to “REAR SHOCK ABSORBER AS-
SEMBLY” on page 4-53.
Connecting arm bolt (frame side)Refer to “REAR SHOCK ABSORBER AS-
SEMBLY” on page 4-53.
1 Silencer clamp 1 Loosen.
2 Silencer 1
3 Exhaust pipe 2 clamp 1 Loosen.
4 Exhaust pipe 2 1
5 Exhaust pipe 1 1
6 Gaskets 3
10
5
9
2 6
1
66
3
84 7 (8)
(6)
30 Nm (3.0 mkgf, 22 ftIbf)T.R
.
30 Nm (3.0 mkgf, 22 ftIbf)T.
R
.
8 Nm (0.8 mkgf, 5.8 ftIbf)T.R
.
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
New
New
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
12 Nm (1.2 mkgf, 8.7 ftIbf)T.R.12 Nm (1.2 mkgf, 8.7 ftIbf)T.R.
20 Nm (2.0 mkgf, 14 ftIbf)T.R
.
New
1st 7 Nm (0.7 mkgf, 5.1 ftlbf)
2nd 10 Nm (1.0 m
kgf, 7.2 ftlbf)T.R
.
LT
LT
LT

ENGINE REMOVAL
5-2
7 Exhaust pipe 1 protector 1
8 Exhaust pipe 2 protector 1
9 Silencer body 1
10 Silencer cap 1
For installation, reverse the removal proce-
dure.
Removing the exhaust pipe
Order Part name Q’ty Remarks
10
5
9
2 6
1
66
3
84 7 (8)
(6)
30 Nm (3.0 mkgf, 22 ftIbf)T.R
.
30 Nm (3.0 mkgf, 22 ftIbf)T.R
.
8 Nm (0.8 mkgf, 5.8 ftIbf)T.R
.
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
New
New
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
12 Nm (1.2 mkgf, 8.7 ftIbf)T.R.12 Nm (1.2 mkgf, 8.7 ftIbf)T.R.
20 Nm (2.0 mkgf, 14 ftIbf)T.R
.
New
1st 7 Nm (0.7 mkgf, 5.1 ftlbf)
2nd 10 Nm (1.0 m
kgf, 7.2 ftlbf)T.R
.
LT
LT
LT

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

ENGINE REMOVAL
5-4
Removing the engine
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.
Rear fender 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.
Air filter case Refer to “THROTTLE BODY” on page 7-5.
Throttle body Refer to “THROTTLE BODY” on page 7-5.
Clutch cable Refer to “CLUTCH” on page 5-37.
Shift pedal Refer to “SHIFT SHAFT” on page 5-49.
1 Engine guard 1
2 Brake pedal 1
3Spring 1
4 Cylinder head breather hose 1
5 Drive sprocket cover 1
6 Drive chain guide 1
New
New
LS
M
8
8
7
6
11
45
New
1 10
3
2

ENGINE REMOVAL
5-5
7 Drive sprocket 1
8 Upper engine bracket 2
9 Lower engine bracket 2
10 Pivot shaft 1
11 Engine 1
For installation, reverse the removal proce-
dure.
Removing the engine
Order Part name Q’ty Remarks
New
New
LS
M
8
8
7
6
11
45
New
1 10
3
2