2011 YAMAHA YZ450F radiator

2-23
CABLE ROUTING DIAGRAM
1. Tension pipe
2. Coolant temperature sensor
coupler
3. Front engine bracket
4. Fuel pump coupler
5. Fuel pump
6. Intake air temperature sensor
coupler
7. Radiator hose 2
8. Radiator breather hose
9. Radiator hose 1
10. Radiator hose 4
11. Radiator pipe 2
12. Radiator hose 3
13. Cylinder head breather hose
14. Frame
15. ECU (electronic control unit)
16. ECU bracket
17. Main harness
18. AC magneto lead
19. Throttle position sensor lead
20. Condenser lead
21. Coolant temperature sensor
lead
22. Ignition coil lead
23. CondenserA. Fasten the wire harness at the
positioning tape to the ECU
bracket with a plastic locking tie.
Face the buckle of the plastic
locking tie downward, and then
cut off the excess end of the tie.
B. Install the cover onto the wire
harness coupler.
C. Route the condenser lead, throt-
tle position sensor lead, coolant
temperature sensor lead, igni-
tion coil lead, and AC magneto
lead under radiator hose 2.
D. Connect the vacuum hose to the
atmospheric pressure sensor,
and then fasten the hose with
the clamp. Make sure to face the
moving part of the sensor rear-
ward.
E. After connecting the condenser
coupler, install the coupler cover
onto the coupler.
F. After connecting the throttle po-
sition sensor coupler, install the
coupler cover onto the coupler.
G. Fasten the AC magneto lead,
condenser lead, throttle position
sensor lead, coolant tempera-
ture sensor lead, and ignition
coil lead to the frame with the
plastic band, making sure to po-
sition the band between the igni-
tion coil bracket and the tension
pipe. Face the buckle of the
plastic band to the right with the
end pointing rearward.
H. Point the end of the vacuum
hose rearward.
I. Fit the bracket into the hole in
the rubber portion of the con-
denser.
J. Fasten the radiator breather
hose to the frame with the plas-
tic band, making sure to position
the band above the front engine
bracket. Face the buckle of the
plastic band outward with the
end pointing rearward.
K. After connecting the coolant
temperature sensor coupler, in-
stall the coupler cover onto the
coupler.L. Route the radiator breather hose
between the down tubes.
M. Fasten the fuel hose and fuel
pump lead with the plastic band,
making sure to position the band
between the bend in the fuel
hose protector and the end of
the protector. Point the end of
the plastic band upward.
N. Insert the projection on the joint
coupler into the hole in the
bracket, and then install the cou-
pler cover onto the coupler.
O. Route the atmospheric pressure
sensor lead, intake air pressure
sensor lead, intake air tempera-
ture sensor lead, fuel injector
lead, and fuel pump lead above
radiator hose 2. Position the
joint coupler above radiator
hose 2.
P. Route the radiator breather hose
to the inside of radiator hose 1
and the front engine bracket.
Q. Hose installation position
(1.3–3.3 mm, 0.05–0.13 in)
R. Clip installation position (0–2.0
mm, 0–0.08 in)
S. Install the washer so that it con-
tacts the bolt head.
T. Install the collar so that the
flange on the collar contacts the
ECU bracket.

3-2
MAINTENANCE INTERVALS
CYLINDER HEAD Inspect carbon deposits and eliminate them.
Inspect and clean ●Change gasket.
CYLINDER Inspect and clean ●Inspect score marks.
Replace ●Inspect wear.
CLUTCH Inspect and adjust ●● Inspect housing, friction plate, clutch
plate and spring.
Replace ●
TRANSMISSION Inspect ●
Replace bearing ●
SHIFT FORK, SHIFT CAM,
GUIDE BAR Inspect ●Inspect wear.
ROTOR NUT Retighten ●●
EXHAUST PIPE, SILENCER,
PROTECTOR Inspect and retighten ●●
Clean ●
Replace fiver ●●* * When the exhaust sound becomes
louder or when a performance drop is
felt.
CRANK Inspect and clean ●●
THROTTLE BODY Inspect ●
SPARK PLUG Inspect and clean ●●
Replace ●
DRIVE CHAIN Use chain lube. Lubricate, slack, alignment ●● Chain slack: 50–60 mm (2.0–2.4 in)
Replace ●
COOLING SYSTEM Check coolant level and leakage ●●
Check radiator cap operation ●
Replace coolant ●Every two years
Inspect hoses ●
OUTSIDE NUTS AND BOLTS Retighten ●● Refer to "STARTING AND BREAK-
IN" section in the CHAPTER 1.
Item
After
break- in Every
race
(about 2.5
hours)
Every third
(about 7.5
hours) Every
fifth
(about 12.5
hours)
As re-
quired Remarks

3-5
PRE-OPERATION INSPECTION AND MAINTENANCE
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.
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
CoolantCheck that coolant is filled up to the radiator cap. Check the cool-
ing system for leakage.P.3-6 – 7
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the fuel
line for leakage.P.1-17
Engine oilCheck that the oil level is correct. Check the crankcase and oil line
for leakage.P.3-9 – 10
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-7
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-8
Brakes Check the play of front brake and effect of front and rear brake. P.3-14 – 17
Drive chainCheck drive chain slack and alignment. Check that the drive chain
is lubricated properly.P.3-17 –18
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-21
SteeringCheck that the handlebar can be turned smoothly and have no ex-
cessive play.P.3-21 – 22
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage.
P.3-18 – 20
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 pipe Check that the exhaust pipe is tightly mounted and has no cracks. P.4-3 – 6
Rear wheel sprocket Check that the rear wheel sprocket tightening bolt is not loose. P.3-17
Lubrication Check for smooth operation. Lubricate if necessary. P.3-23
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-19
Lead connectorsCheck that the AC magneto, ECU and ignition coil are connected
tightly.P.1-10 – 11
SettingsIs the machine set suitably for the condition of the racing course
and weather or by taking into account the results of test runs be-
fore racing? Are inspection and maintenance completely done?P.8-1 – 5

3-6
ENGINE
ENGINE
CHECKING THE COOLANT LEVEL
Do not remove the radiator cap
"1", drain bolt and hoses when the
engine and radiator are hot. Scald-
ing hot fluid and steam may be
blown out under pressure, which
could cause serious injury. When
the engine has cooled, place a
thick towel over the radiator cap,
slowly rotate the cap counter-
clockwise to the detent. This pro-
cedure allows any residual
pressure to escape. When the
hissing sound has stopped, press
down on the cap while turning
counterclockwise and remove it.
Hard water or salt water is harmful
to the engine parts. You may use
distilled water, if you can't get soft
water.
1. Place the machine on a level
place, and hold it in an upright po-
sition.
2. Remove:
• Radiator cap
3. Check:
• Coolant level "a"
Coolant level low→Add coolant.
1. RadiatorCHANGING THE COOLANT
Do not remove the radiator cap
when the engine is hot.
Take care so that coolant does not
splash on painted surfaces. If it
splashes, wash it away with water.
1. Place a container under the en-
gine.
2. Remove:
• Coolant drain bolt "1"
3. Remove:
• Radiator cap
Drain the coolant completely.
4. Clean:
• Cooling system
Thoroughly flush the cooling sys-
tem with clean tap water.
5. Install:
• Copper washer
• Coolant drain bolt
6. Fill:
• Radiator
•Engine
To specified level.
• Do not mix more than one type of
ethylene glycol antifreeze con-
taining corrosion inhibitors for
aluminum engine.
• Do not use water containing im-
purities or oil.
Handling notes of coolant:
The coolant is harmful so it should be
handled with special care.
• When coolant splashes to your
eye.
Thoroughly wash your eye with
water and see your doctor.
• When coolant splashes to your
clothes.
Quickly wash it away with water
and then with soap.
• When coolant is swallowed.
Quickly make him vomit and take
him to a doctor.
7. Install:
• Radiator cap
Start the engine and warm it up
for a several minutes.
8. Check:
• Coolant level
Coolant level low→Add coolant.
CHECKING THE RADIATOR CAP
1. Inspect:
• Seal (radiator cap) "1"
• Valve and valve seat "2"
Crack/damage→Replace.
Exist fur deposits "3" →Clean or
replace.
Coolant drain bolt:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Recommended coolant:
High quality ethylene
glycol anti-freeze con-
taining anti-corrosion
for aluminum engine
Coolant "1" and water
(soft water) "2" mixing ra-
tio:
50%/50%
Coolant capacity:
1.13 L (0.99 Imp qt, 1.19
US qt)

3-7
ENGINE
CHECKING THE RADIATOR CAP
OPENING PRESSURE
1. Attach:
• Radiator cap tester "1" and adapt-
er "2"
Apply water on the radiator cap seal.
3. Radiator cap
2. Apply the specified pressure.
3. Inspect:
• Pressure
Impossible to maintain the speci-
fied pressure for 10 seconds →
Replace.
CHECKING THE COOLING
SYSTEM
1. Inspect:
• Coolant level
2. Attach:
• Radiator cap tester "1" and adapt-
er "2"3. Apply the specified pressure.
• Do not apply pressure more than
specified pressure.
• Radiator should be filled fully.
4. Inspect:
•Pressure
Impossible to maintain the speci-
fied pressure for 10 seconds →
Repair.
• Radiator
• Radiator hose joint
Coolant leakage → Repair or re-
place.
• Radiator hose
Swelling → Replace.
ADJUSTING THE CLUTCH LEVER
POSITION
1. Adjust:
• Clutch lever position
Clutch lever position adjustment
steps:
a. Loosen the locknuts "1".
b. Turn the adjusting bolt "2" until the
clutch lever position "a" is in the
desiered position .
c. Tighten the locknuts.
2. Adjust:
• Clutch cable free play
Refer to "ADJUSTING THE
CLUTCH CABLE FREE PLAY".ADJUSTING THE CLUTCH CABLE
FREE PLAY
1. Check:
• Clutch lever free play "a"
Out of specification→Adjust.
2. Adjust:
• Clutch lever free play
Clutch lever free play adjustment
steps:
a. Loosen the locknuts "1".
b. Turn the adjuster "2" until free
play "a" is within the specified lim-
its.
c. Tighten the locknuts.
• Before adjustment, expose the ad-
juster by moving the boot "3" and
cap "4" away.
• Make minute adjustment on the le-
ver side using the adjuster "5".
• After adjustment, check proper op-
eration of clutch lever.
3. Install:
•Cap "1"
• Boot "2" Radiator cap tester:
YU-24460-01/90890-
01325
Radiator cap tester
adapter:
YU-33984/90890-01352
Radiator cap opening
pressure:
108–137 kPa (1.08–1.37
kg/cm
2, 15.4–19.5 psi)
Radiator cap tester:
YU-24460-01/90890-
01325
Radiator cap tester
adapter:
YU-33984/90890-01352
Standard pressure:
196 kPa (1.96 kg/cm2,
27.9 psi)
Locknut:
5 Nm (0.5 m•kg, 3.6
ft•lb)
Clutch lever free play "a"
:
7–12 mm (0.28–0.47 in)
Locknut:
4 Nm (0.4 m•kg, 2.9
ft•lb)

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

4-8
RADIATOR
11 Pipe 1/O-ring 1/1 Order Part name Q'ty Remarks

4-9
RADIATOR
HANDLING NOTE
Do not remove the radiator cap
when the engine and radiator are
hot. Scalding hot fluid and steam
may be blown out under pressure,
which could cause serious injury.
When the engine has cooled, open
the radiator cap by the following
procedure:
Place a thick rag, like a towel, over
the radiator cap, slowly rotate the
cap counterclockwise to the de-
tent. This procedure allows any re-
sidual pressure to escape. When
the hissing sound has stopped,
press down on the cap while turn-
ing counterclockwise and remove
it.
CHECKING THE RADIATOR
1. Inspect:
• Radiator core "1"
Obstruction→Blow out with com-
pressed air through rear of the ra-
diator.
Bent fin→Repair/replace.
INSTALLING THE RADIATOR
1. Install:
• O-ring "1"
• Pipe 1 "2"
• Radiator hose 1 "3"
• O-ring "4"
• Pipe 2 "5"
• Radiator hose 3 "6"• Radiator hose 4 "7"
2. Install:
• Grommet "1"
Face the smaller portion "a" of the
grommet inward.
3. Install:
• Radiator hose 2 "1"
• Left radiator "2"
4. Install:
• Radiator breather hose "1"
• Right radiator "2"
Refer to "CABLE ROUTING DIA-
GRAM" section in the CHAPTER
2.5. Install:
• Radiator guard "1"
First fit the inner hook portion "a" and
then the outer one "b" onto the radia-
tor.
6. Install:
• Bolt (radiator guard) "1"
Pipe 1:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Radiator hose 1:
2 Nm (0.2 m•kg, 1.4
ft•lb)
Pipe 2:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Radiator hose 3:
2 Nm (0.2 m•kg, 1.4
ft•lb)
Radiator hose 4:
2 Nm (0.2 m•kg, 1.4
ft•lb)
Radiator hose 2:
2 Nm (0.2 m•kg, 1.4
ft•lb)
Left radiator:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Right radiator:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (radiator guard) "1":
10 Nm (1.0 m•kg, 7.2
ft•lb)