radiator cap YAMAHA YZ450F 2012 Owners Manual

1-5
DESCRIPTION
DESCRIPTION
• The machine you have purchased may differ slightly from those shown in the following.
• Designs and specifications are subject to change without notice.
1. Clutch lever
2. Front brake lever
3. Throttle grip
4. Radiator cap
5. Fuel tank cap
6. Engine stop switch
7. Kickstarter crank
8. Fuel tank
9. Radiator10. Coolant drain bolt
11. Rear brake pedal
12. Valve joint
13. Air cleaner
14. Drive chain
15. Shift pedal
16. Oil level check window
17. Starter knob/idle screw
18. Front fork

1-12
SPECIAL TOOLS
SPECIAL TOOLS
The proper special tools are necessary for complete and accurate tune-up and assembly. Using the correct special tool will
help prevent damage caused by the use of improper tools or improvised techniques. The shape and part number used for
the special tool differ by country, so two types are provided. Refer to the list provided to avoid errors when placing an order.
• For U.S.A. and Canada, use part number starting with "YM-", "YU-" or "ACC-".
• For others, use part number starting with "90890-".
Tool name/Part number How to use Illustration
Dial gauge and stand
YU-3097, 90890-01252
Stand
YU-1256These tools are used to check each
part for runout or bend.
Crankshaft installing tool
Crankshaft installing pot
YU-90050, 90890-01274
Crankshaft installing bolt
YU-90050, 90890-01275
Spacer (crankshaft installer)
YM-91044, 90890-04081
Adapter (M12)
YU-90063, 90890-01278These tools are used to install the
crankshaft.
Piston pin puller set
YU-1304, 90890-01304 This tool is used to remove the pis-
ton pin.
Radiator cap tester
YU-24460-01, 90890-01325
Radiator cap tester adapter
YU-33984, 90890-01352These tools are used for checking
the cooling system.
Steering nut wrench
YU-33975, 90890-01403 This tool is used when tighten the
steering ring nut to specification.

2-8
MAINTENANCE SPECIFICATIONS
Throttle position sensor:----
Throttle position sensor maximum resistance 5 kΩ----
Throttle position sensor variable resistance 0–2 kΩ (full closed) ----
Throttle position sensor input voltage 4–6 V ----
Fuel injection sensor:----
Crankshaft position sensor resistance 248–372 Ω----
Intake air pressure sensor output voltage 3.57–3.71 V at 101.3kPa (1.013 kg/cm
2,
14.41 psi)----
Atmospheric pressure sensor output voltage 3.57–3.71 V at 101.3kPa (1.013 kg/cm
2,
14.41 psi)----
Intake air temperature sensor 5.4–6.6 kΩat 0 °C (32 °F)
290–390 Ωat 80 °C (176 °F)----
Idling condition:----
Engine idle speed 1,900–2,100 r/min ----
Oil temperature 55–65 °C (131–149 °F) ----
Lubrication system:
Oil filter type Paper type ----
Oil pump type Trochoid type ----
Tip clearance 0.12 mm or less (0.0047 in or less) 0.20 mm (0.008
in)
Side clearance 0.09–0.17 mm (0.0035–0.0067 in) 0.24 mm (0.009
in)
Housing and rotor clearance 0.03–0.10 mm (0.0012–0.0039 in) 0.17 mm (0.007
in)
Bypass valve setting pressure 40–80 kPa (0.4–0.8 kg/cm
2, 5.69–11.38
psi)----
Cooling:
Radiator core size
Width 121.4 mm (4.78 in) ----
Height 235 mm (9.25 in) ----
Thickness 28 mm (1.10 in) ----
Radiator cap opening pressure 108–137 kPa (1.08–1.37 kg/cm
2,
15.4–19.5 psi)----
Radiator capacity (total) 0.62 L (0.55 Imp qt, 0.66 US qt) ----
Water pump
Type Single-suction centrifugal pump ----Item Standard Limit

2-11
TIGHTENING TORQUES
TIGHTENING TORQUES
ENGINE
△- marked portion shall be checked for torque tightening after break-in or before each race.
ItemThread
sizeQ'ty Tightening torque Remarks
Spark plug M10S 1 13 Nm (1.3 m•kg, 9.4 ft•lb)
Camshaft cap M6 8 10 Nm (1.0 m•kg, 7.2 ft•lb)
Cylinder head blind plug screw M12 2 28 Nm (2.8 m•kg, 20 ft•lb)
Oil passage plug M8 1 15 Nm (1.5 m•kg, 11 ft•lb)
Cylinder head (stud bolt) M6 3 7 Nm (0.7 m•kg, 5.1 ft•lb)
Cylinder head (bolt) M10 4 Refer to TIP.
*1
Cylinder head (bolt) M6 2 10 Nm (1.0 m•kg, 7.2 ft•lb)
Cylinder head cover M6 3 10 Nm (1.0 m•kg, 7.2 ft•lb)
Cylinder M6 1 10 Nm (1.0 m•kg, 7.2 ft•lb)
Timing chain tensioner M6 2 10 Nm (1.0 m•kg, 7.2 ft•lb)
Timing chain tensioner cap bolt M6 1 7 Nm (0.7 m•kg, 5.1 ft•lb)
Timing chain guide stopper plate (exhaust
side)M6 2 10 Nm (1.0 m•kg, 7.2 ft•lb)
Exhaust pipe (nut) M6 3 10 Nm (1.0 m•kg, 7.2 ft•lb)
Exhaust pipe and frame M8 1 20 Nm (2.0 m•kg, 14 ft•lb)
△Silencer M8 2 30 Nm (3.0 m•kg, 22 ft•lb)
Silencer clamp (front) M8 1 12 Nm (1.2 m•kg, 8.7 ft•lb)
Silencer clamp (rear) M8 1 16 Nm (1.6 m•kg, 11 ft•lb)
Starter knob/Idle screw M12 1 2 Nm (0.2 m•kg, 1.4 ft•lb)
Throttle body joint M6 2 10 Nm (1.0 m•kg, 7.2 ft•lb)
Throttle body joint clamp M5 1 3 Nm (0.3 m•kg, 2.2 ft•lb)
△Air filter case M6 3 7 Nm (0.7 m•kg, 5.1 ft•lb)
Air filter joint and air filter case M4 9 1 Nm (0.1 m•kg, 0.7 ft•lb)
Air filter case cover M5 2 5 Nm (0.5 m•kg, 3.6 ft•lb)
Air filter joint clamp M4 1 4 Nm (0.4 m•kg, 2.9 ft•lb)
Throttle cable adjust bolt and locknut M6 1 4 Nm (0.4 m•kg, 2.9 ft•lb)
Throttle cable (pull) M10 1 7 Nm (0.7 m•kg, 5.1 ft•lb)
Throttle cable (return) M10 1 7 Nm (0.7 m•kg, 5.1 ft•lb)
Throttle cable cover M5 2 4 Nm (0.4 m•kg, 2.9 ft•lb)
Air duct M6 3 7 Nm (0.7 m•kg, 5.1 ft•lb)
Radiator M6 4 10 Nm (1.0 m•kg, 7.2 ft•lb)
Radiator hose clamp M6 8 2 Nm (0.2 m•kg, 1.4 ft•lb)
Radiator pipe 1 M6 1 10 Nm (1.0 m•kg, 7.2 ft•lb)
Radiator pipe 2 M6 1 10 Nm (1.0 m•kg, 7.2 ft•lb)
Impeller M8 1 14 Nm (1.4 m•kg, 10 ft•lb)
Water pump housing cover M6 4 10 Nm (1.0 m•kg, 7.2 ft•lb)
Coolant drain bolt M6 1 10 Nm (1.0 m•kg, 7.2 ft•lb)
Oil pump cover M4 1 2 Nm (0.2 m•kg, 1.4 ft•lb)
Oil pump M6 2 10 Nm (1.0 m•kg, 7.2 ft•lb)
Oil pump drive gear shaft M6 1 10 Nm (1.0 m•kg, 7.2 ft•lb)

2-21
CABLE ROUTING DIAGRAM
1. Clutch cable
2. Throttle cable (return)
3. Throttle cable (pull)
4. Cable holder
5. Clamp
6. Rectifier/regulator
7. Ignition coil
8. Ignition coil coupler
9. AC magneto coupler
10. Radiator hose 2
11. Ground lead terminal
12. Plug cap
13. Ignition coil bracket
14. Clamp (lock)
15. Clamp (clip)
16. AC magneto lead
17. ECU bracket
18. Cylinder head cover installing
boltA. Pass the clutch cable, throttle
cables, and engine stop switch
lead through the cable holder.
Pass the clutch cable through
the lower guide only.
B. Route the engine stop switch
lead to the inside of the clip.
C. Fasten the rectifier/regulator
lead and engine stop switch lead
(wire harness end).
D. Insert the projection on the en-
gine stop switch coupler into the
hole in the bracket.
E. Insert the projection on the recti-
fier/regulator coupler into the
hole in the bracket.
F. Position the ignition coil bracket
to the outside of the ignition coil,
and insert the bolts from the igni-
tion coil side.
G. Fasten the AC magneto lead to
the ignition coil bracket with a
plastic locking tie, making sure
to position the tie above the low-
er mounting portion of the brack-
et. Face the buckle of the plastic
locking tie forward, and then cut
off the excess end of the tie.
H. Route the ignition coil lead be-
tween the condenser and the ig-
nition coil.
I. Fit the clip portion of the clamp
into the ignition coil bracket and
fasten the clutch cable with the
locking portion of the clamp.
J. Route the clutch cable to the
outside of the AC magneto lead.
K. Route the throttle cables under
radiator hose 2, making sure not
to twist the cables.
L. Route the AC magneto lead to
the inside of the throttle cables
and clutch cable.
M. Install the ground lead terminal
between the ECU bracket and
the cable holder, making sure to
position the terminal between
the stoppers.
N. Push in the spark plug cap com-
pletely, making sure that there is
no gap between the cylinder
head cover and the cap.
O. Pass the high tension cord so
that it may not go right over the
cylinder head cover installing
bolt when viewed directly from
above.
P. Apply sealant to the slit and in-
ner surface of the grommet, and
then install the grommet at the
position shown.

3-2
MAINTENANCE INTERVALS
CYLINDER HEADInspect 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 – 4
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
desired 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
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)