fuel YAMAHA YZ450F 2011 Owner's Guide

3-25
ELECTRICAL
TROUBLESHOOTING
The following guide for troubleshooting does not cover all the possible causes of problems. If the following problems occur,
perform the specified checks or maintenance jobs. If a problem occurs that is not listed in this manual or if the problem
cannot be corrected by the procedures provided in this manual, contact your Yamaha dealer.
Engine starting problems, engine idling speed problems, and medium and high-speed performance problems
• Engine does not start even though the kickstarter is pushed.
• Engine starts, but soon stops.
Engine idling speed problems
• Engine idling speed fluctuates.
• Engine idling speed is high.
• Engine idling speed is low.
Medium and high-speed performance problems
• Engine speed does not increase.
• Engine knocks.
• Engine speed increases suddenly.
• Loss of engine power.
INSPECTION STEPS
If the aforementioned problems have occurred, perform the following inspection steps in the order given.
Check that the fuel tank is filled with fresh gaso-
line.No good→
Fill the fuel tank.
OK↓
Check that the fuel tank breather hose is not
clogged. (Refer to "INCLUDED PARTS" section
in the CHAPTER 1.)No good→
Repair or replace.
OK↓
Adjusting the engine idling speed(Refer to "AD-
JUSTING THE ENGINE IDLLING SPEED" sec-
tion in the CHAPTER 3.)No good→
Adjust.
OK↓
Check that the fuel hose is connected properly
and is not kinked or pinched.No good→
Repair.
OK↓
Check the spark plug for dirt, the spark plug gap,
and the spark plug cap. (Refer to "CHECKING
THE SPARK PLUG" section in the CHAPTER 3.)No good→
Clean or adjust.
OK↓
Check that the air filter element is installed cor-
rectly and is not clogged. (Refer to "CLEANING
THE AIR FILTER" section in the CHAPTER 3.)No good→
Clean or repair.
OK↓
Checking the sensors, injector and ignition coil
connection.No good→
Repair or replace.
OK↓
Installed condition of ECU (Refer to "CHECKING
THE ECU" section in the CHAPTER 7.)No good→
Repair.
OK↓
Check the assembled condition of the throttle
body, and check the throttle valve and its sur-
rounding parts for dirt.No good→
Repair or clean.
OK↓
Consult a Yamaha dealer.

4-7
RADIATOR
RADIATOR
REMOVING THE RADIATOR
Order Part name Q'ty Remarks
Drain the coolant.Refer to "CHANGING THE COOLANT" sec-
tion in the CHAPTER 3.
SeatRefer to "SEAT AND SIDE COVERS" sec-
tion.
Fuel tank Refer to "FUEL TANK" section in the CHAP-
TER 6.
Air filter caseRefer to "THROTTLE BODY" section in the
CHAPTER 6.
1 Radiator guard 2
2 Radiator hose clamp 8 Only loosening.
3 Right radiator 1
4 Radiator hose 2 1
5 Radiator hose 4 1
6 Radiator hose 3 1
7 Pipe 2/O-ring 1/1
8 Radiator breather hose 1
9 Left radiator 1
10 Radiator hose 1 1

4-10
CAMSHAFTS
CAMSHAFTS
REMOVING THE CYLINDER HEAD COVER
Order Part name Q'ty Remarks
Seat Refer to "SEAT AND SIDE COVERS" sec-
tion.
Fuel tank Refer to "FUEL TANK" section in the CHAP-
TER 6.
CoverRefer to "THROTTLE BODY" section in the
CHAPTER 6.
1 Spark plug 1
2 Cylinder head breather hose 1
3 Bolt (cylinder head cover) 3
4 Cylinder head cover 1
5 Cylinder head cover gasket 1
6 Timing chain guide (top side) 1

4-15
CYLINDER HEAD
CYLINDER HEAD
REMOVING THE CYLINDER HEADOrder Part name Q'ty Remarks Seat Refer to "SEAT AND SIDE COVERS" sec-
tion.
Fuel tank Refer to "FUEL TANK" section in the CHAP- TER 6.
Exhaust pipe and silencer Refer to "EXHAUST PIPE AND SILENCER"
section.
Radiator Refer to "RADIATOR" section
Throttle body Refer to "THROTTLE BODY" section in the
CHAPTER 6.
Camshaft Refer to "CAMSHAFTS" section.

4-45
AC MAGNETO
AC MAGNETO
REMOVING THE AC MAGNETO
Order Part name Q'ty Remarks
Seat Refer to "SEAT AND SIDE COVERS" sec-
tion.
Fuel tank Refer to "FUEL TANK" section in the
CHAPER 6.
Disconnect the AC magneto lead
1 Left crankcase cover 1
2 Gasket 1
3 Dowel pin 2
4 Nut (rotor) 1 Refer to removal section.
5 Rotor 1 Refer to removal section.
6 Stator 1
7 Woodruff key 1

4-47
ENGINE REMOVAL
ENGINE REMOVAL
REMOVING THE ELECTRONIC PARTS
Order Part name Q'ty Remarks
Hold the machine by placing the suitable stand
under the frame.Refer to "HANDLING NOTE".
SeatRefer to "SEAT AND SIDE COVERS" sec-
tion.
Fuel tankRefer to "FUEL TANK" section in the CHAP-
TER 6.
Air filter caseRefer to "THROTTLE BODY" section in the
CHAPTER 6.
Radiator Refer to "RADIATOR" section.
1 Rectifier/regulator 1
2 Ignition coil bracket 1
3 Ignition coil 1
4 Atmospheric pressure sensor 1
5 Condenser 1
6 AC magneto lead 1 Disconnect.
7 Coolant temperature sensor coupler 1 Disconnect.

5-16
FRONT FORK
FRONT FORK
REMOVING THE FRONT FORK
Order Part name Q'ty Remarks
Hold the machine by placing the suitable stand
under the engine.Refer to "HANDLING NOTE".
Front wheel Refer to "FRONT WHEEL AND REAR
WHEEL" section.
Front brake caliper Refer to "FRONT BRAKE AND REAR
BRAKE" section.
Number plateRefer to "SEAT, FUEL TANK AND SIDE
COVERS" section in the CHAPTER 4.
1 Protector 1
2 Pinch bolt (upper bracket) 2 Only loosening.
3 Damper assembly 1Loosen when disassembling the front fork.
Refer to removal section.
4 Pinch bolt (lower bracket) 2 Only loosening.
5 Front fork 1

6-1
FUEL TANK
FUEL SYSTEM
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 knowledge and skill concerning servicing are request-
ed not to undertake inspection, adjustment, disassembly, or reassembly only by reference to this manual. It may lead to
servicing trouble and mechanical damage.
FUEL TANK
REMOVING THE FUEL TANK
Order Part name Q'ty Remarks
SeatRefer to "SEAT AND SIDE COVERS" section
in the chapter 4.
Air scoop (left/right) 1/1Refer to "SEAT AND SIDE COVERS" section
in the chapter 4.
1 Fuel pump coupler 1 Disconnect.
2 Fuel hose 1 Refer to removal section.
3 Fuel tank bolt 2
4 Fuel tank 1 Refer to removal section.
5 Fuel pump bracket 1
6 Fuel pump assembly 1 Refer to removal section.
7O-ring 1
6

6-2
FUEL TANK
REMOVING THE FUEL TANK
1. Extract the fuel in the fuel tank through the fuel tank cap with a
pump.
Be careful not to damage the fuel
pump.
2. Remove: • Fuel pump coupler
Although the fuel has been re-
moved from the fuel tank be care-
ful when removing the fuel hoses,
since there may be fuel remaining
in it.
• Before disconnecting the fuel hose, clean the area around the fuel hose
connector.
• Before removing the fuel hose, place a few rags in the area under
where it will be removed.
• To disconnect the fuel hose from the fuel tank, remove the fuel hose
connector holder "a", and then slide
the fuel hose connector cover.
• Slide the fuel hose connector cover "1" in the direction of the arrow
mark, and press the buttons "2" on
both sides of the connector to re-
move the fuel hose.
• Disconnecting the hose is done by hand. There is no need to use tools.
• To prevent sand, dust, and other
foreign material from entering the
fuel pump, install the included fuel
hose joint cover 1 "3" and fuel hose
joint cover 2 "4" onto the fuel pump
and disconnected fuel hose.
3. Remove:•Fuel tank
Do not set the fuel tank down so that
the installation surface of the fuel
pump is directly under the tank.
REMOVING THE FUEL PUMP
1. Remove:•Fuel pump
Do not drop the fuel pump or give
it a strong shock.
CHECKING THE FUEL PUMP
BODY
1. Check:
• Fuel pump bodyCracks/damage → Replace fuel
pump assembly.
CHECKING THE FUEL PUMP
OPERATION
1. Check: • Fuel pump operationRefer to "CHECKING THE FUEL
PRESSURE" section.
INSTALLING THE FUEL PUMP
1. Install: •Fuel pump
• Fuel pump bracket
•Do not damage th e installation
surfaces of the fuel tank when in-
stalling the fuel pump.
• Before installing the fuel pump,
remove any dirt and other foreign
material from the installation sur-
face on the fuel tank.
• Always use a new fuel pump gas- ket.
• Install the lip on the fuel pump gas- ket upward.
• Install the fuel pump as shown in
the illustration.
• Align the projection "a" on the fuel pump with the slot in the fuel pump
bracket. Align the slot "b" on the fuel
tank damper with the projection "a"
on the fuel pump.
• Tighten the fuel pump bolts in stag- es in a crisscross pattern.
INSTALLING THE FUEL TANK
1. Install:•Fuel hose
•When installing the fuel hose,
make sure that it is securely con-
nected, and that the fuel hose
holders are in the correct posi-
tion, otherwise the fuel hose will
not be properly installed.
• Be sure not to kink or pinch the
fuel hose.
• Insert the fuel hose on the fuel pipe
until you hear a definite "click".
• Slide the fuel hose connector cover
"1" at the fuel hose end in the direc-
tion of the arrow.
• Install the fuel hose connector hold-
er "a".
• Make sure that the fuel hose and fuel pump lead are routed through
the guide on the cover.
Fuel pump bracket bolt
4 Nm (0.4 m•kg, 2.9
ft•lb)

6-3
FUEL TANK
2. Install:
• Fuel pump coupler
• Air scoop (left/right)
• Seat
Refer to "SEAT AND SIDE COV-
ERS" in the chapter 4.
CHECKING THE FUEL PRESSURE
1. Check:
• Pressure regulator operation
2. Remove the fuel tank.
Refer to "REMOVEING
THE FUEL TANK" section.
3. Connect the pressure gauge "1"
and adapter "2" to the fuel injec-
tion pipe.
4. Install the fuel tank.
Refer to "INSTALLING THE
FUEL TANK" section.
5. Start the engine.
6. Measure the fuel pressure.CHECKING AND REPLACING THE
DUMPER
1. Inspect:
• Damper 1 "1"
• Damper 2 "2"
• Damper 3 "3"
Wear/damage → Replace
• Affix dampers 1 and 3 so that the
arrow on each damper is pointing
outward.
• Affix damper 2 so that the edge of
the damper contacts the edge "a" of
the frame.
Pressure gauge
YU-03153/90890-03153
Fuel pressure adapter
YM-03186/90890-03186
Fuel pressure
312–328 kPa (3.12–3.28
kg/cm
2)
20mm
20mm
35mm 35mm