2014 YAMAHA YZ450F fuel cap

PRE-OPERATION INSPECTION AND MAINTENANCE
3-7
EAS1SL1067
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation, practice or a race, make sure the machine is in good operating
condition.
Before using this machine, check the following points.
EAS1SL1068GENERAL INSPECTION AND MAINTENANCE
TIP
Perform usual maintenance enough so that, in the race course, a confirmation of that and simple set-
ting adjustments may only be left, in order to get enough time to use effectively.
ITEMinspectPage
CoolantCheck that coolant is filled up to the radiator cap.
Check the cooling system for leakage.3-8 – 10
FuelCheck that a fresh gasoline is filled in the fuel tank.
Check the fuel line for leakage.1-22
Engine oilCheck that the oil level is correct. Check the crank-
case and oil line for leakage.3-14 – 16
Gear shifter and clutchCheck that gears can be shifted correctly in order and
that the clutch operates smoothly.3-10 – 11
Throttle grip/Housing
Check that the throttle grip operation and free play
are correctly adjusted. Lubricate the throttle grip and
housing, if necessary.
3-11 – 12
BrakesCheck the play of front brake and effect of front and
rear brake.3-21 – 27
Drive chainCheck drive chain slack and alignment. Check that
the drive chain is lubricated properly.3-27
4-64 – 65
WheelsCheck for excessive wear and tire pressure. Check
for loose spokes and have no excessive play.3-32 – 33
SteeringCheck that the handlebar can be turned smoothly and
have no excessive play.3-33 – 34
Front forks and rear
shock absorberCheck that they operate smoothly and there is no oil
leakage.3-28 – 32
Cables (wires)
Check that the clutch and throttle cables move
smoothly. Check that they are not caught when the
handlebars are turned or when the front forks travel
up and down.
—
Exhaust pipeCheck that the exhaust pipe is tightly mounted and
has no cracks.3-13 – 14
Rear wheel sprocketCheck that the rear wheel sprocket tightening bolt is
not loose.4-8 – 9
LubricationCheck for smooth operation. Lubricate if necessary. 3-12 , 3-34
Bolts and nutsCheck the chassis and engine for loose bolts and
nuts.1-25 – 26
Lead connectorsCheck that the AC magneto, ECU and ignition coil are
connected tightly.1-12 – 14
Settings
Is the machine set suitably for the condition of the rac-
ing course and weather or by taking into account the
results of test runs before racing? Are inspection and
maintenance completely done?10-1 – 8

ENGINE
3-12
LUBRICATING THE THROTTLE CABLE
1. Remove:• Cover (throttle cable cap) “1”
• Cover (grip cap) “2”
• Throttle grip cap “3”
2. Lubricate: • Throttle cable end “a”
3. Install: • Throttle grip cap
• Screw (throttle grip cap)
4. Install: • Cover (grip cap)
• Cover (throttle cable cap)
EWA
WARNING
Check that the throttle grip moves smooth-
ly. If this does not move smoothly, correct
the installed positions.
EAS1SL1080CLEANING THE AIR FILTER ELEMENT
1. Remove:• Fuel tank cap cover “1”Refer to “FUEL TANK CAP” on page 1-21.
• Air filter case cover “2” 2. Remove:
• Air filter mounting bolt “1”
• Air filter element “2”
• Air filter guide “3” (from the air filter element)
3. Wash: • Air filter element
EWA
WARNING
Do not use gasoline or organic (acid/alka-
line) volatile oil for washing.
TIP
After washing the element with air filter cleaner
or kerosene, squeeze and dry it completely.
ECA33DD016
NOTICE
Do not twist the element when squeezing
the element.
Recommended lubricant
Lithium-soap-based grease
Screw (throttle grip cap) 3.8 Nm (0.38 m·kgf, 2.8 ft·lbf)
T R..
1
2
13
2

ENGINE
3-13
4. Check:• Air filter elementDamage  Replace.
5. Foam-air-filter oil or equivalent oil to the ele- ment
TIP
Squeeze out the excess oil. Element should be
wet but not dripping.
6. Install:• Air filter guide “1” (to the air filter element)
• Air filter element “2”
• Air filter mounting bolt “3”
7. Install: • Air filter case cover “1”
• Air filter case cover mounting bolt
TIP
Align the air filter case cover groove “a” with the
air filter case edge “b”.
8. Install:• Fuel tank cap cover
EAS1SL1081
CHECKING THE THROTTLE BODY JOINT
1. Check:• Throttle body joint “1”
Refer to “CHECKING THE THROTTLE
BODY JOINT” on page 7-8.
EAS1SL1082CHECKING THE BREATHER HOSES
1. Check:• Breather hose “1”Crack/damage  Replace.
Loose connection  Connect properly.
ECA14920
NOTICE
Make sure that the breather hoses are rout-
ed correctly.
EAS1SL1083CHECKING THE EXHAUST SYSTEM
1. Remove:
• Exhaust pipe protector
2. Check:
• Exhaust pipe 1
• Exhaust pipe 2
• SilencerCrack/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
Oil application quantify
50 g
Air filter mounting bolt 2 Nm (0.2 m·kgf, 1.4 ft·lbf)
Air filter case cover mounting bolt 6 Nm (0.6 m·kgf, 4.3 ft·lbf)
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31
2
T R..
a
b
1
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)
1
T R..

ENGINE
3-16
7. Pour the specified amount of engine oil into
the oil filler cap hole.
8. Install:
• Oil filler cap
9. Check:
• Oil level
Refer to “CHECKING THE ENGINE OIL
LEVEL” on page 3-14.
10.Check:
• Engine oil pressure
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Slightly loosen the oil pressure check bolt
“1.”
EWA
WARNING
When the engine is started with the check
bolt removed, oil will spout; therefore, al
-
ways loosen it before the checkup.
Start the engine and keep it idling until oil
starts to seep from the oil pressure check
bolt.
EWA
WARNING
Always keep the engine idling speed during
the checkup without increasing the engine
speed.
ECA
NOTICE
If no engine oil seeps out after one minute,
immediately turn the engine off so it will not
seize.
b. If no engine oil seeps out, check the engine
oil for leaks, and the engine oil passage and
the oil pump for damage.
c. Check the oil pressure again.
d. Tighten the oil pressure check bolt.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS1SL1087ADJUSTING THE ENGINE IDLING SPEED
TIP
• Because the air pressure is lower at high alti-
tudes, the air-fuel mixture will become richer.
If the idling speed is low, turn the starter knob/
idle screw a few clicks counterclockwise to in
-
crease the speed before the adjustment.
• Before adjusting the engine idling speed,
make sure that the air filter element is not
clogged, the engine compression is proper,
and the throttle grip free play is proper.
• Adjust the engine idling speed with the starter
knob/idle screw pushed in completely.
1. Start the engine, and warm this up until the
oil has reached the specified temperature.
2. Attach the pocket tester with temperature
probe “1” to the oil drain bolt.
3. Install:
• Digital tachometer
Engine oil quantity
With oil filter element replace-
ment
0.69 L (0.73 US qt, 0.61 Imp.qt)
Quantity (disassembled)
0.95 L (1.00 US qt, 0.84 Imp.qt)
1
Oil pressure check bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Oil temperature
55-65 °C (131–149 °F)
Digital tachometer
90890-06760
YU-39951-B
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1

ELECTRICAL SYSTEM
3-35
EAS1SL1114
ELECTRICAL SYSTEM
EAS1SL1115CHECKING THE SPARK PLUG
1. Remove:
• Seat
• Air scoop (left/right)
Refer to “GENERAL CHASSIS” on page 4-
1.
• Fuel tank “1”
Refer to “FUEL TANK” on page 7-1.ECA1DX1001
NOTICE
Do not use too much force to pull the hose.
TIP
Remove the fuel tank, turn this 180° clockwise,
and put it in the frame “2” as shown.
2. Remove:
• Spark plug cap
• Spark plug
Refer to “CAMSHAFT” on page 5-11.ECA13330
NOTICE
In order not to allow the dirt accumulated
around the spark plug to drop from the
spark plug hole into the cylinder, clean it be
-
fore removing the spark plug.
3. Check:
• Spark plug type
Wrong type  Replace.
4. Check:
• Electrode
Damage/wear  Replace the spark plug.
• Insulator
Abnormal color  Replace the spark plug.
Normal color is medium-to-light tan.
5. Clean:
• Spark plug
(with a spark plug cleaner or a wire brush)
6. Measure:
• Spark plug gap “a”
Out of specification  Adjust the spark plug
gap.
7. Install:
• Spark plug
TIP
Before installing the spark plug, clean the spark
plug and gasket surface.
8. Install:
• Spark plug cap
• Fuel tank
• Air scoop (left/right)
• Seat
• Side cover (left/right)
Refer to “GENERAL CHASSIS” on page 4-
1.
EAS1SL1116CHECKING THE IGNITION TIMING
1. Remove:
• Timing mark accessing screw “1”Manufacturer/model
NGK/CR8E
1
1
2
Spark plug gap
0.7–0.8 mm (0.028–0.031 in)
Spark plug
13 Nm (1.3 m·kgf, 9.4 ft·lbf)T R..
1

GENERAL CHASSIS
4-2
EAS1SL1119REMOVING THE LEFT SIDE COVER
1. Remove:• Bolt (side cover)
• Side cover “1”
TIP
Draw the left side cover “1” backward to re-
move it because its projection “a” is inserted in
the rear frame.
EAS1SL1120REMOVING THE SEAT
TIP
The fuel tank cap cover and the seat are cou-
pled with each other with a plastic band.
When removing the seat, always remove the
fuel tank cap cover beforehand.
1. Remove:• Fuel tank cap cover “1”
Refer to “FUEL TANK CAP” on page 1-21.
2. Remove: • Seat “1”
EAS1SL1121
REMOVING THE NUMBER PLATE
1. Remove:• Bolt (number plate)
• Number plate “1”
TIP
• The projection “a” is inserted into the band of
the number plate. Pull the band off the projec-
tion before removal.
• Remove the clutch cable “2” from the cable
guide “b” on the number plate.
• The projection “c” on the lower bracket is in- serted into the number plate. Remove the
number plate by pulling it off the projection.
1
a
1
1
1

FUEL TANK
7-2
EAS1SL1306REMOVING THE FUEL TANK
1. Extract the fuel in the fuel tank through the
fuel tank cap with a pump.
2. Remove:
• Fuel hose couplerEWA23P1001
WARNING
Cover the fuel hose connection with a cloth
when disconnecting it. This is because re
-
sidual pressure in the fuel hose could cause
fuel to spurt out when the hose is removed.
ECA23P1090
NOTICE
Make sure that the fuel hose is disconnect-
ed by hand. Do not forcefully disconnect the
hose with tools.
TIP
• To disconnect the fuel hose from the fuel tank,
remove the fuel hose connector holder “a”,
and then slide the fuel hose connector cover.
• To remove the fuel hose from the fuel rail,
slide the fuel hose connector cover “1” on the
end of the hose in the direction of the arrow
shown, press the two buttons “2” on the sides
of the connector, and then remove the hose.
• Before removing the hose, place a few cloths
in the area under where it will be removed.
• To prevent sand, dust, and other foreign ma-
terials from entering the fuel pump, install the
included fuel hose joint cover 1 “3” and the
fuel hose joint cover 2 “4” onto the disconnect
-
ed fuel hose and the fuel pump.
3. Remove:
• Side cover (left/right)
• Seat
• Air scoop (left/right)
• Fuel tank
TIP
Do not set the fuel tank down on the installation
surface of the fuel pump. Be sure to lean the
fuel tank against a wall or the like.
EAS1SL1307REMOVING THE FUEL PUMP
1. Remove:
• Fuel pumpECA14720
NOTICE
Do not drop the fuel pump or give it a strong
shock.
EAS1SL1308CHECKING THE FUEL PUMP BODY
1. Check:
• Fuel pump body
Obstructions  Clean.
Cracks/damage  Replace the fuel pump
assembly.
EAS1SL1309INSTALLING THE FUEL PUMP
1. Install:
• Fuel pump gasket
• Fuel pump
• Fuel pump bracket
TIP
• Take care not to damage the installation sur-
faces of the fuel tank.
• Always use a new fuel pump gasket.
• Install the lip on the fuel pump gasket upward.
• Install the fuel pump as shown in the figure.
• Align the projection “a” on the fuel pump with
the slot “b” in the fuel pump bracket.
• Tighten the fuel pump bolts in the proper tight-
ening sequence as shown.
a
1
2
Fuel pump bolts
4.0 Nm (0.40 m·kgf, 2.9 ft·lbf)
3 4
New
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8
ELECTRICAL SYSTEM
IGNITION SYSTEM.......................................................................................... 8-2
CIRCUIT DIAGRAM ................................................................................... 8-2
TROUBLESHOOTING ............................................................................... 8-4
CHARGING SYSTEM....................................................................................... 8-6
CIRCUIT DIAGRAM ................................................................................... 8-6
TROUBLE SHOOTING .............................................................................. 8-8
FUEL INJECTION SYSTEM........................................................................... 8-10
CIRCUIT DIAGRAM ................................................................................. 8-10
YAMAHA DIAGNOSTIC TOOL ................................................................ 8-12
TROUBLESHOOTING DETAILS ............................................................. 8-13
FUEL PUMP SYSTEM.................................................................................... 8-32
CIRCUIT DIAGRAM ................................................................................. 8-32
TROUBLESHOOTING ............................................................................. 8-34
ELECTRICAL COMPONENTS....................................................................... 8-36
CHECKING THE SWITCHES .................................................................. 8-38
CHECKING THE IGNITION SPARK GAP................................................ 8-41
CHECKING THE SPARK PLUG CAP ...................................................... 8-41
CHECKING THE IGNITION COIL ............................................................ 8-41
CHECKING THE CRANKSHAFT POSITION SENSOR........................... 8-42
CHECKING THE ECU .............................................................................. 8-43
CHECKING THE STATOR COIL ............................................................. 8-43
CHECKING THE RECTIFIER/REGULATOR ........................................... 8-43
CHECKING THE COOLANT TEMPERATURE SENSOR........................ 8-44
CHECKING THE THROTTLE POSITION SENSOR ................................ 8-44
CHECKING THE THROTTLE POSITION SENSOR 
INPUT VOLTAGE .................................................................................... 8-43
CHECKING THE INTAKE AIR PRESSURE SENSOR ............................ 8-46
CHECKING THE INTAKE AIR TEMPERATURE SENSOR ..................... 8-46
CHECKING THE NEUTRAL SWITCH ..................................................... 8-46
CHECKING THE FUEL INJECTOR ......................................................... 8-47