air filter YAMAHA YZ450F 2012 User Guide

3-10
ENGINE
CHANGING THE ENGINE OIL
1. Start the engine and let it warm up
for several minutes.
2. Stop the engine and place an oil
pan under the drain bolt.
3. Remove:
• Oil filler cap "1"
• Drain bolt (with gasket) "2"
• Drain bolt (with gasket) "3"
Drain the engine oil.
4. If the oil filter is to be replaced dur-
ing this oil change, remove the fol-
lowing parts and reinstall them.
Replacement steps:
a. Remove the oil filter element cov-
er "1" and oil filter element "2".
b. Check the O-rings "3", if cracked
or damaged, replace them with a
new one.
c. Install the oil filter element and oil
filter element cover.
5. Install:
• Gaskets
• Oil drain bolt (oil pan)
• Oil drain bolt (oil tank)
6. Fill:
• Engine oil
7. Install:
• Oil filler cap
8. Inspect:
• Engine (for oil leaks)
• Oil levelCHECKING THE OIL PRESSURE
1. Check:
• Oil pressure
Checking steps:
a. Slightly loosen the oil pressure
check bolt "1".
b. Start the engine and keep it idling
until oil starts to seep from the oil
pressure check bolt. If no oil
comes out after one minute, turn
the engine off so it will not seize.
c. Check oil passages and oil pump
for damage or leakage.
d. Start the engine after solving the
problem(s) and recheck the oil
pressure.
e. Tighten the oil pressure check
bolt.
ADJUSTING THE ENGINE IDLING
SPEED
• Because the air pressure is lower at
high altitudes, the air-fuel mixture
will become richer. If the engine
idling speed is low, turn the starter
(choke) knob/idling screw a few
clicks counterclockwise to increase
the idling speed.
• Before adjusting the engine idling
speed, make sure that the com-
pression pressure is within specifi-
cation and that the air filter element
is not clogged.
• Adjust the engine idling speed with
the starter (choke) knob/idling
screw pushed in completely.
1. Start the engine and warm it up
until the engine oil has reached
the specified temperature.
2. Use a temperature probe tester
"1" and contact it to the drain bolt
thread. Recommended brand:
YAMALUBE
Recommended engine
oil type
SAE10W-30, SAE 10W-
40, SAE10W-50, SAE
15W-40, SAE 20W-40 or
SAE 20W-50
Recommended engine
oil grade
API service SG type or
higher, JASO standard
MA
Oil filter element cover:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Oil drain bolt (oil pan):
20 Nm (2.0 m•kg, 14
ft•lb)
Oil drain bolt (oil tank):
20 Nm (2.0 m•kg, 14
ft•lb)
Oil quantity:
Periodic oil change:
0.95 L (0.84 Imp qt,
1.00 US qt)
With oil filter replace-
ment:
1.0 L (0.88 Imp qt, 1.06
US qt)
Total amount:
1.2 L (1.06 Imp qt, 1.27
US qt)
Oil pressure check bolt:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Oil temperature:
55.0–65.0 °C
(131–149°F)

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.

4-5
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

4-45
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.

6-4
THROTTLE BODY
THROTTLE BODY
REMOVING THE THROTTLE BODY
Order Part name Q'ty Remarks
SeatRefer to "SEAT AND SIDE COVERS" section
in the chapter 4.
Air scoop (left/right)Refer to "SEAT AND SIDE COVERS" section
in the chapter 4.
Fuel tank Refer to "FUEL TANK" section.
1 Cover 1
2 Air filter case 1
3 Fuel hose 1
4 Fuel injector coupler 1 Disconnect.
5 Intake air pressure sensor coupler 1 Disconnect. (I.D. MARK "2")
6 Throttle cable cover 1
7 Throttle cable 2
8 Throttle body 1
9 Throttle body joint 1

7-36
ELECTRICAL COMPONENTS
ELECTRICAL
COMPONENTS
CHECKING THE COOLANT
TEMPERATURE SENSOR
1. Remove:
•Coolant temperature sensor
Refer to "REMOVING THE CYL-
INDER HEAD" section in the
CHAPTER 4.
•Handle the coolant temperature
sensor with special care.
•Never subject the coolant tem-
perature sensor to strong
shocks. If the coolant tempera-
ture sensor is dropped, replace
it.
2. Check:
• Coolant temperature sensor re-
sistance
3. Connect:
•Tester
Tester (+) lead → Brown lead "1"
Tester (-) lead → Black/Blue lead
"2"
4. Immerse the coolant temperature
sensor in a container filled with
coolant.
Make sure the coolant temperature
sensor terminals do not get wet.
5. Place a thermometer "3" in the
coolant.
6. Slowly heat the coolant, and then
let it cool to the specified temper-
ature indicated in the table.Out of specification → Replace.
CHECKING THE INTAKE AIR
PRESSURE SENSOR
1. Check:
• Intake air pressure sensor output
voltage
2. Connect:
• Test harness S–pressure sensor
(3P) "1"
•Tester
Tester (+) lead → Pink/White lead
(wire harness color)
Tester (-) lead → Black/Blue lead
(wire harness color)
3. Connect the FI diagnostic tool
sub-wire harness to a battery, and
then set the switch on the harness
to "ON".
When checking the intake air pres-
sure sensor, do not start the en-
gine.
4. Measure the intake air pressure
sensor output voltage.
Out of specification → ReplaceCHECKING THE INTAKE AIR
TEMPERATURE SENSOR
1. Remove:
• Intake air temperature sensor
(from the air filter case.)
•Handle the intake air temperature
sensor with special care.
•Never subject the intake air tem-
perature sensor to strong
shocks. If the intake air tempera-
ture sensor is dropped, replace
it.
2. Check:
• Intake air temperature sensor re-
sistance
3. Connect:
•Tester
Tester (+) lead → Brown/White
lead "1"
Tester (-) lead →Black/Blue lead
(wire harness color) "2"
Out of specification → Replace.
CHECKING THE ATMOSPHERIC
PRESSURE SENSOR
1. Check:
• Atmospheric pressure sensor out-
put voltage
2. Connect:
• Test harness S- pressure sensor
(3P) "1"
•Tester
Tester (+) lead → Pink lead (wire
harness color)
Tester (-) lead → Black/Blue lead
(wire harness color)
B/L Br
Coolant
tempera-
ture sensor
resistanceTester se-
lector posi-
tion
210–220 Ω
(100°C,
212°F)Ω×100
2.51–2.78
kΩ (20°C,
68°F)kΩ×1
Test harness S–pressure
sensor (3P)
YU-03207/90890-03207
Output volt-
ageTester se-
lector posi-
tion
3.4–3.8 V DCV
Intake air
tempera-
ture sensor
resistanceTester se-
lector posi-
tion
5.4–6.6 kΩ
(0°C, 32°F)kΩ×1
290–390 Ω
(80°C,
176°F)Ω×100
Br/WB/L

7-37
ELECTRICAL COMPONENTS
3. Connect the FI diagnostic tool
sub-wire harness to a battery, and
then set the switch on the harness
to "ON".
When checking the atmospheric
pressure sensor, do not start the
engine.
4. Measure the atmospheric pres-
sure sensor output voltage.
Out of specification→Replace.
CHECKING THE RECTIFIER/
REGULATOR
1. Connect:
• Connect the tester to the coupler
for connecting optional part
Tester (+) lead→ Red lead "1"
Tester (-) lead→ Black/White lead
"2"
2. Start the engine.
3. Check:
• Rectifier/regulato output voltage
Out of specification → Replace.
4. Stop the engine.CHECKING THE FUEL INJECTORS
1. Remove:
•Seat
•Fuel tank
• Air filter case
2. Check:
•Injector resistance
3. Connect:
•Tester
Tester (+) lead → Injector termi-
nal "1"
Tester (-) lead → Injector termi-
nal "2"
Out of specification→Replace. Test harness S–pressure
sensor (3P):
YU-03207/90890-03207
Output volt-
ageTester se-
lector posi-
tion
3.4–3.8 V DCV
Output volt-
ageTester se-
lector posi-
tion
14.1–14.9 V DCV
Lg
R
B/W
Injector re-
sistanceTester se-
lector posi-
tion
12.0 Ω
(20°C, 68°F) Ω×10