2014 YAMAHA YZ450F key

EAS1SL1003
INTRODUCTION
Congratulations on your purchase of a Yamaha YZ series. This model is the culmination of Yamaha's
vast experience in the production of pacesetting racing machines. It represents the highest grade of
craftsmanship and reliability that have made Yamaha a leader.
This manual explains operation, inspection, basic maintenance and tuning of your machine. If you
have any questions about this manual or your machine, please contact your Yamaha dealer.
TIP
Yamaha continually seeks advancements in product design and quality. Therefore, while this manual
contains the most current product information available at the time of printing, there may be minor
discrepancies between your machine and this manual. If you have any questions concerning this
manual, please consult your Yamaha dealer.
EWA1DX0001
WARNING
PLEASE READ THIS MANUAL CAREFULLY AND COMPLETELY BEFORE OPERATING THIS
MACHINE. DO NOT ATTEMPT TO OPERATE THIS MACHINE UNTIL YOU HAVE ATTAINED A
SATISFACTORY KNOWLEDGE OF ITS CONTROLS AND OPERATING FEATURES AND UNTIL
YOU HAVE BEEN TRAINED IN SAFE AND PROPER RIDING TECHNIQUES. REGULAR INSPEC
-
TIONS AND CAREFUL MAINTENANCE, ALONG WITH GOOD RIDING SKILLS, WILL ENSURE
THAT YOU SAFETY ENJOY THE CAPABILITIES AND THE RELIABILITY OF THIS MACHINE.
EAS1SL1004
IMPORTANT MANUAL INFORMATION
Particularly important information is distinguished in this manual by the following notations.
This is the safety alert symbol. It is used to alert you to potential personal
injury hazards. Obey all safety messages that follow this symbol to avoid
possible injury or death.
A WARNING indicates a hazardous situation which, if not avoided, could
result in death or serious injury.
A NOTICE indicates special precautions that must be taken to avoid
damage to the vehicle or other property.
A TIP provides key information to make procedures easier or clearer.
WARNING
NOTICE
TIP

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

OIL PUMP AND BALANCER GEAR
5-55
Removing the balancer
OrderPart nameQ’tyRemarks
Primary driven gearRefer to “CLUTCH” on page 5-37.
Right crankcase coverRefer to “CLUTCH” on page 5-37.
StatorRefer to “AC MAGNETO” on page 5-59.
1Nut (balancer)1
2Nut (primary drive gear)1
3Nut (balancer shaft driven gear)1
4Lock washer1
5Balancer1
6Straight key1
7Conical washer1
8Primary drive gear1
9Balancer shaft drive gear1
10Lock washer1
11Balancer weight gear1
For installation, reverse the removal proce-dure.
45 Nm (4.5 mkgf, 33 ftIbf)T.R.
100 Nm (10 mkgf, 72 ftlbf)T.R.
50 Nm (5.0 mkgf, 36 ftIbf)T.R.
New

OIL PUMP AND BALANCER GEAR
5-58
NOTICE
After tightening the bolts, make sure that
the oil pump turns smoothly.
2. Install:
• Balancer weight gear “1”
TIP
Install the balancer weight gear and balancer
shaft with their lower splines “a” aligning with
each other.
3. Install:
• Balancer drive gear “1”
TIP
• Align the punched mark “a” on the balancer
drive gear with the punched mark “b” on the
balancer weight gear.
• Install the balancer drive gear and crankshaft
with the lower splines “c” aligning with each
other.
4. Install:
• Lock washer “1”
• Balancer weight gear nut “2”
• Primary drive gear “3”
• Conical washer “4”
• Primary drive gear nut “5”
• Straight key “6”
•Balancer “7”
• Lock washer “8”
• Balancer nut “9”
TIP
• Apply engine oil to the contact surface and
threaded portion of the primary drive gear nut.
• Apply engine oil to the contact surfaces of the
conical washer.
• Place an aluminum plate “a” between the
teeth of the balancer drive gear “10” and bal
-
ancer weight gear “11”.
• Install the conical washer with its convex sur-
face “b” outward.
5. Bend the lock washer tab.
Balancer weight gear nut
50 Nm (5.0 m·kgf, 36 ft·lbf)
Primary drive gear nut
100 Nm (10 m·kgf, 72 ft·lbf)
New
T R..
New
T R..
Balancer nut
45 Nm (4.5 m·kgf, 33 ft·lbf)
New
T R..
1
2 11
10
a
3 45
1011
a
b
3

AC MAGNETO
5-59
EAS1SL1272
AC MAGNETO
Removing the AC magneto
OrderPart nameQ’tyRemarks
Engine oilDrain.Refer to “CHANGING THE ENGINE OIL” on page 3-15.
SeatRefer to “GENERAL CHASSIS” on page 4-1.
Air scoop (left)Refer to “GENERAL CHASSIS” on page 4-1.
1AC magneto leadDisconnect.
2Crankshaft position sensor lead1Disconnect.
3Shift pedal1
4Left crankcase cover1
5Gaskets1
6Dowel pin2
7Holder1
8Stator assembly1
9Rotor1
10Woodruff key1
For installation, reverse the removal proce-dure.
110
2
4 7 5 8 3
96
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
8 Nm (0.8 mkgf, 5.8 ftIbf)T.R.
8 Nm (0.8 mkgf, 5.8 ftIbf)T.R.
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
65 Nm (6.5 mkgf, 47 ftIbf)T.R.
New
LT
6
LT
LT

AC MAGNETO
5-60
EAS1SL1273REMOVING THE AC MAGNETO
1. Remove:
• Nut (rotor) “1”
• Washers
2. Remove:
• Rotor “1”
Use the rotor puller “2” to remove the rotor.
• Woodruff key
EAS1SL1274CHECKING THE AC MAGNETO
1. Check:
• Rotor inner surface “a”
• Stator outer surface “b”
Damage  Inspect the crankshaft runout
and crankshaft bearing.
EAS1SL1275
CHECKING THE WOODRUFF KEY
1. Check:
• Woodruff key “1”
Damage  Replace.
EAS1SL1276INSTALLING THE AC MAGNETO
1. Install:
• Stator “1”
• Screw (stator) “2”
• Crankshaft position sensor “3”
• Bolt (crankshaft position sensor) “4”
• Holder “5”
• Bolt (holder) “6”
TIP
• Apply the sealant to the grommet of the AC
magneto lead.
• Tighten the stator screws using the T25 bit.
• Pass the AC magneto lead “a” through the
crankcase cover side.
Rotor puller
90890-04151
YM-04151
1
ab
Screw (stator)
8 Nm (0.8 m·kgf, 5.8ft·lbf)
LOCTITE®
Bolt (crankshaft position sensor)
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
LOCTITE®
Holder
8 Nm (0.8 m·kgf, 5.8 ft·lbf)
LOCTITE®
Three Bond No.1215®
90890-85505
T R..
T R..
26
5
4
3
4a
1
LT
LT

AC MAGNETO
5-61
2. Install:
• Woodruff key “1”
• Rotor “2”
TIP
• Clean the contact surfaces of the tapered por-
tions 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.
3. Install:
• Washers
• Nut (rotor) “1”
4. Install:
• Dowel pin “1”
• Gasket (left crankcase cover) “2”
• Left crankcase cover “3”
• Lead holder “4”
• Bolt (left crankcase cover) “5”
TIP
Tighten the bolts in stages and in a crisscross
pattern.
5. Connect:
• AC magneto lead
Refer to “CABLE ROUTING DIAGRAM” on
page 2-33.
Nut (rotor)
65 Nm (6.5 m·kgf, 47 ft·lbf)
Bolt (left crankcase cover)
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
b11
c
2 a
T R..
1
New
T R..
1
1
2
3
5
5
5
5
4
45

TROUBLE SHOOTING
9-1
EAS1SL1349
TROUBLE SHOOTING
EAS1SL1350GENERAL INFORMATION
TIP
The following guide for troubleshooting does
not cover all the possible causes of trouble. It
should be helpful, however, as a guide to basic
troubleshooting. Refer to the relative procedure
in this manual for checks, adjustments, and re
-
placement of parts.
EAS1SL1351STARTING FAILURES
Engine
1. Cylinder and cylinder head
• Loose spark plug
• Loose cylinder head or cylinder
• Damaged cylinder head gasket
• Damaged cylinder gasket
• Worn or damaged cylinder
• Incorrect valve clearance
• Improperly sealed valve
• Incorrect valve-to-valve-seat contact
• Incorrect valve timing
• Faulty valve spring
• Seized valve
2. Piston and piston ring(s)
• Improperly installed piston ring
• Damaged, worn or fatigued piston ring
• Seized piston ring
• Seized or damaged piston
3. Air filter
• Improperly installed air filter
• Clogged air filter element
4. Crankcase and crankshaft
• Improperly assembled crankcase
• Seized crankshaft
Fuel system
1. Fuel tank
• Empty fuel tank
• Clogged fuel tank breather hose
• Deteriorated or contaminated fuel
• Clogged or damaged fuel hose
2. Fuel pump
• Faulty fuel pump
3. Throttle body
• Deteriorated or contaminated fuel
• Sucked-in air
Electrical system
1. Spark plug
• Incorrect spark plug gap
• Incorrect spark plug heat range
• Fouled spark plug
• Worn or damaged electrode
• Worn or damaged insulator
2. Ignition coil
• Cracked or broken ignition coil body
• Broken or shorted primary or secondary
coils
3. Ignition system
• Faulty ECU
• Faulty crankshaft position sensor
• Broken generator rotor woodruff key
4. Switches and wiring
• Faulty ECU
• Faulty engine stop switch
• Broken or shorted wiring
• Faulty neutral switch
• Improperly grounded circuit
• Loose connections
EAS1SL1352INCORRECT ENGINE IDLING SPEED
Engine
1. Cylinder and cylinder head
• Incorrect valve clearance
• Damaged valve train components
2. Air filter
• Clogged air filter element
Fuel system
1. Throttle body
• Damaged or loose throttle body joint
• Improperly synchronized throttle bodies
• Improper throttle cable free play
• Flooded throttle body
Electrical system
1. Spark plug
• Incorrect spark plug gap
• Incorrect spark plug heat range
• Fouled spark plug
• Worn or damaged electrode
• Worn or damaged insulator
• Faulty spark plug cap
2. Ignition coil
• Broken or shorted primary or secondary
coils
• Cracked or broken ignition coil