2016 YAMAHA YZ450F stop start

ENGINE
3-9
5. Install:
• Copper washer
• Coolant drain bolt
6. Pour coolant.
EWA13040
WARNING
• If coolant splashes in your eyes, thorough-
ly wash them with water and consult a
doctor.
• If coolant splashes on your clothes, quick-
ly wash it away with water and then with
soap and water.
• If coolant is swallowed, induce vomiting
and get immediate medical attention.
ECA13480
NOTICE
• Adding water instead of coolant lowers the
antifreeze content of the coolant. If water
is used instead of coolant check, and if
necessary, correct the antifreeze concen-
tration of the coolant.
• Use only distilled water. However, if dis-
tilled water is not available, soft water may
be used.
• If coolant comes into contact with painted
surfaces, immediately wash them with wa-
ter.
• Do not mix different types of antifreeze.
7. Install:
• Radiator cap
8. Start the engine, warm this up for several
minutes, stop it, and then wait for it to cool
down.
9. Check:
• Coolant level
Refer to “CHECKING THE COOLANT LEV-
EL” on page 3-8.
EASB111072CHECKING THE RADIATOR CAP
1. Check:
• Seal (radiator cap) “1”
• Valve and valve seat “2”
Crack/damage  Replace.
Exist fur deposits  Clean or replace.
EASB111073CHECKING THE RADIATOR CAP VALVE
OPENING PRESSURE
1. Check:
• Radiator cap valve opening pressure
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a. Install the radiator cap tester adapter “2” and
the radiator cap tester “3” to the radiator cap
“1,” and activate the tester to check whether
it can stay for 5 to 10 seconds within stan-
dard pressure values.
TIP
Before attaching the cap to the tester, apply
water to its sealing surface.
No stay  Replace. Coolant drain bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Recommended coolant
High quality ethylene glycol
anti-freeze containing anti-cor-
rosion for aluminum engine
Radiator (including all routes)
1.04 L (1.10 US qt, 0.92 Imp.qt)
Coolant mixing ratio
1:1 (Coolant:Water)
New
T R..
Radiator cap valve opening pres-
sure
108–137 kPa (1.08–1.37 kg/cm
2,
15.7–19.9 psi)
Radiator cap tester
90890-01325
Mityvac cooling system tester kit
YU-24460-A
Radiator cap tester adapter
90890-01352
Pressure tester adapter
YU-33984

ENGINE
3-14
EASB111082CHECKING THE EXHAUST SYSTEM
1. Remove:
• Exhaust pipe protector
2. Check:
• Exhaust pipe 1
• Exhaust pipe 2
• Silencer
Crack/damage  Replace.
Refer to “ENGINE REMOVAL” on page 5-1.
• Exhaust gas
Leaks  Replace the gasket.
Refer to “ENGINE REMOVAL” on page 5-1.
3. Check:
• Tightening torques
4. Install:
• Exhaust pipe protectorEASB111083CHECKING THE FUEL LINE
1. Remove:
• Seat
• Side cover (left/right)
• Air scoop (left/right)
Refer to “GENERAL CHASSIS” on page 4-
1.
• Fuel tank
Refer to “FUEL TANK” on page 7-1.
2. Check:
• Fuel hose “1”
Crack/damage  Replace.
Loose connection  Connect properly.
3. Install:
• Fuel tank
Refer to “FUEL TANK” on page 7-1.
• Air scoop (left/right)
• Seat
• Side cover (left/right)
Refer to “GENERAL CHASSIS” on page 4-
1.
EASB111084CHECKING THE ENGINE OIL LEVEL
1. Stand the vehicle upright on a level surface.
2. Start the engine, warm this up for 2–3 min-
utes, and then stop the engine and wait
about 1 minute.
3. Check:
• Oil level
Make sure that the engine oil level is above
the minimum level mark “a” shown for the oil
level check window “1”, and that the engine
oil does not come out by removing the oil
check bolt “2”.
The minimum level mark “a” or below  Add
the engine oil until its level exceeds the min-
imum level mark “a”.
Engine oil coming out of the oil check bolt 
Drain it until its last drop is out. Exhaust pipe bolt 1 and nut “1”
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Exhaust pipe 1 and exhaust pipe
2 bolt “2”
12 Nm (1.2 m·kgf, 8.7 ft·lbf)
Exhaust pipe 2 and silencer bolt
“3”
12 Nm (1.2 m·kgf, 8.7 ft·lbf)
Silencer and silencer bracket bolt
“4”
30 Nm (3.0 m·kgf, 22 ft·lbf)
Exhaust pipe protector screw
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
LOCTITE®
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2
1
4
3
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1

ENGINE
3-15
ECA33DD018
NOTICE
• Since engine oil also lubricates the clutch,
the wrong oil types or additives could
cause clutch slippage. Therefore, do not
add any chemical additives.
• Do not allow foreign material to enter the
crankcase.
EASB111085CHANGING THE ENGINE OIL
Stand the vehicle upright on a level surface.
1. Start the engine, warm this up for several
minutes, and then stop the engine and wait
about 5 minutes.
2. Place an oil pan under the drain bolt.
3. Remove:
• Oil filler cap “1”
• Drain bolt (with gasket) “2”4. If the oil filter element is also to be replaced,
perform the following procedure.
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a. Remove the oil filter element cover “1” and
oil filter element “2”.
b. Replace the O-rings “3”.
c. Install the new oil filter element and the oil fil-
ter element cover.
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5. To check the oil strainer, perform the follow-
ing procedure.
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a. Remove the oil strainer “1”.
b. Check the oil strainer.
Damage  Replace.
Clogging due to dirt  Wash with kerosene.
c. Replace the O-rings “2”. Recommended brand
YAMALUBE
Type
SAE 10W-40, SAE 10W-50, SAE
15W-40, SAE 20W-40 or SAE
20W-50
Recommended engine oil grade
API service SG type or higher,
JASO standard MA
12
a
Oil filter element cover bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
1
2
1
3
2
New
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CLUTCH......................................................................................................... 5-38
REMOVING THE CLUTCH ...................................................................... 5-41
CHECKING THE FRICTION PLATES...................................................... 5-41
CHECKING THE CLUTCH PLATES ........................................................ 5-41
CHECKING THE CLUTCH SPRINGS...................................................... 5-41
CHECKING THE CLUTCH HOUSING ..................................................... 5-42
CHECKING THE CLUTCH BOSS ............................................................ 5-42
CHECKING THE PRESSURE PLATE ..................................................... 5-42
CHECKING THE PUSH LEVER SHAFT .................................................. 5-42
CHECKING THE CLUTCH PUSH RODS ................................................ 5-42
CHECKING THE PRIMARY DRIVE GEAR .............................................. 5-42
CHECKING THE PRIMARY DRIVEN GEAR ........................................... 5-43
INSTALLING THE OIL SEAL................................................................... 5-43
INSTALLING THE RIGHT CRANKCASE COVER ................................... 5-43
INSTALLING THE CLUTCH ..................................................................... 5-44
INSTALLING THE KICKSTARTER LEVER ............................................. 5-46
KICKSTATER................................................................................................. 5-47
REMOVING THE KICK SHAFT ASSEMBLY ........................................... 5-48
CHECKING THE KICK SHAFT AND RATCHET WHEEL ........................ 5-48
CHECKING THE KICK GEAR, KICK IDLE GEAR AND RATCHET
WHEEL .................................................................................................... 5-48
INSTALLING THE KICK SHAFT ASSEMBLY .......................................... 5-48
INSTALLING THE KICK IDLE GEAR ....................................................... 5-49
SHIFT SHAFT................................................................................................. 5-50
REMOVING THE SHIFT GUIDE AND SHIFT LEVER ASSEMBLY ......... 5-52
REMOVING THE SEGMENT ................................................................... 5-52
CHECKING THE SHIFT SHAFT .............................................................. 5-52
CHECKING THE SHIFT GUIDE AND SHIFT LEVER ASSEMBLY ......... 5-52
CHECKING THE STOPPER LEVER ....................................................... 5-52
INSTALLING THE STOPPER LEVER ..................................................... 5-53
INSTALLING THE SEGMENT.................................................................. 5-53
INSTALLING THE SHIFT GUIDE AND SHIFT LEVER ASSEMBLY ....... 5-53
INSTALLING THE SHIFT SHAFT ............................................................ 5-54
INSTALLING THE SHIFT PEDAL ............................................................ 5-54
OIL PUMP AND BALANCER GEAR............................................................. 5-55
REMOVING THE BALANCER ................................................................. 5-57
CHECKING THE PRIMARY DRIVE GEAR, BALANCER SHAFT
DRIVE GEAR, AND BALANCER WEIGHT GEAR .................................. 5-57
CHECKING THE BALANCER .................................................................. 5-57
CHECKING THE OIL PUMP .................................................................... 5-57
ASSEMBLING THE OIL PUMP ................................................................ 5-58
INSTALLING THE OIL PUMP AND BALANCER GEAR .......................... 5-59

THROTTLE BODY
7-8
EASB111314CHECKING THE INJECTOR
1. Check:
• Injectors
Obstruction  Replace, and check the fuel
pump and the fuel injection system.
Refer to “FUEL INJECTION SYSTEM” on
page 8-10.
Deposits  Replace.
Damage  Replace.
2. Check:
• Injector resistance
Refer to “CHECKING THE FUEL INJEC-
TOR” on page 8-46.
EASB111315CHECKING THE THROTTLE BODY
1. Check:
• Throttle body
Cracks/damage  Replace.
2. Check:
• Fuel passages
Obstructions  Clean.
ECA
NOTICE
• Before removing the throttle body, clean
the area around the throttle body to pre-
vent dirt and other foreign material from
falling into the engine.
• If the throttle body is subject to strong
shocks or dropped during cleaning, re-
place it.
• Do not use any caustic carburetor clean-
ing solution.
• Do not directly push the throttle valves to
open them.
• Do not loosen the throttle valve stopper
screw “1”, throttle valve pulley nut “2”, or
throttle valve screw “3”. A loss of perfor-
mance may occur.
• Do not use compressed air to clean the
throttle body. Foreign materials may ad-
here to the intake air pressure sensor pas-
sage “a” and fuel injector “b” in the
throttle body.3. Check:
• Starter knob/idle screw passage “c”
Obstruction  Blow out with compressed
air.
EASB111316CHECKING THE THROTTLE BODY JOINT
1. Check:
• Throttle body joint “1”
Crack/damage  Replace.
1 2
3
ba
c
1

TROUBLESHOOTING
9-1
EASB111348
TROUBLESHOOTING
EASB111349GENERAL 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.
EASB111350STARTING 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 airElectrical 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
EASB111351INCORRECT 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

TROUBLESHOOTING
9-2
3. Ignition system
• Faulty ECU
• Faulty crankshaft position sensor
• Broken generator rotor woodruff key
EASB111352POOR MEDIUM-AND-HIGH-SPEED PER-
FORMANCE
Refer to “STARTING FAILURES” on page 9-1.
Engine
1. Air filter
• Clogged air filter element
Fuel system
1. Fuel pump
• Faulty fuel pump
2. Throttle body
• Defective throttle body
3. ECU
• Faulty ECU
EASB111353SHIFTING IS DIFFICULT
Refer to “CLUTCH” on page 5-38.
EASB111354SHIFT PEDAL DOES NOT MOVE
Engine
1. Shift shaft
• Bent shift shaft
2. Shift drum and shift forks
• Foreign object in a shift drum groove
• Seized shift fork
• Bent shift fork guide bar
3. Transmission
• Seized transmission gear
• Foreign object between transmission gears
• Improperly assembled transmission
EASB111355JUMPS OUT OF GEAR
Engine
1. Shift shaft
• Incorrect shift pedal position
• Improperly returned stopper lever
2. Shift forks
• Worn shift fork
3. Shift drum
• Incorrect axial play
• Worn shift drum groove
4. Transmission
• Worn gear dog
EASB111356
CLUTCH SLIPS
Engine
1. Clutch
• Improperly assembled clutch
• Loose or fatigued clutch spring
• Worn friction plate
• Worn clutch plate
2. Engine oil
• Incorrect oil level
• Incorrect oil viscosity (low)
• Deteriorated oil
EASB111357CLUTCH DRAGS
Engine
1. Clutch
• Unevenly tensioned clutch springs
• Warped pressure plate
• Bent clutch plate
• Swollen friction plate
• Bent clutch push rod
• Damaged clutch boss
• Burnt primary driven gear bushing
2. Engine oil
• Incorrect oil level
• Incorrect oil viscosity (high)
• Deteriorated oil
EASB111358OVERHEATING
Engine
1. Cylinder head and piston
• Heavy carbon buildup
• Clogged coolant passages
2. Engine oil
• Incorrect oil level
• Incorrect oil viscosity
• Inferior oil quality
Cooling system
1. Coolant
• Low coolant level
2. Radiator
• Damaged or leaking radiator
• Faulty radiator cap
• Bent or damaged radiator fin
3. Water pump
• Damaged or faulty water pump
• Damaged hose
• Improperly connected hose
• Damaged pipe
• Improperly connected pipe