2012 YAMAHA YZ450F stop start

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

1-17
CONTROL FUNCTIONS
CONTROL FUNCTIONS
ENGINE STOP SWITCH
The engine stop switch "1" is located
on the left handlebar. Continue push-
ing the engine stop switch till the en-
gine comes to a stop.
CLUTCH LEVER
The clutch lever "1" is located on the
left handlebar; it disengages or en-
gages the clutch. Pull the clutch lever
to the handlebar to disengage the
clutch, and release the lever to en-
gage the clutch. The lever should be
pulled rapidly and released slowly for
smooth starts.
SHIFT PEDAL
The gear ratios of the constant-mesh
5 speed transmission are ideally
spaced. The gears can be shifted by
using the shift pedal "1" on the left
side of the engine.
KICKSTARTER CRANK
Rotate the kickstarter crank "1" away
from the engine. Push the starter
down lightly with your foot until the
gears engage, then kick smoothly
and forcefully to start the engine. This
model has a primary kickstarter crank
so the engine can be started in any
gear if the clutch is disengaged. In
normal practices, however, shift to
neutral before starting.THROTTLE GRIP
The throttle grip "1" is located on the
right handlebar; it accelerates or de-
celerates the engine. For accelera-
tion, turn the grip toward you; for
deceleration, turn it away from you.
FRONT BRAKE LEVER
The front brake lever "1" is located on
the right handlebar. Pull it toward the
handlebar to activate the front brake.
REAR BRAKE PEDAL
The rear brake pedal "1" is located on
the right side of the machine. Press
down on the brake pedal to activate
the rear brake.
STARTER KNOB/IDLE SCREW
The starter knob/idle screw "1" is
used when starting a cold engine.
Pull the starter knob/idle screw out to
open the circuit for starting. When the
engine has warmed up, push it in to
close the circuit.
STARTING AND BREAK-IN
FUEL
Always use the recommended fuel as
stated below. Also, be sure to use
new gasoline the day of a race.
Use only unleaded gasoline. The
use of leaded gasoline will cause
severe damage to the engine inter-
nal parts such as valves, piston
rings, and exhaust system, etc.
Your Yamaha engine has been de-
signed to use premium unleaded gas-
oline with a pump octane number
[(R+M)/2] of 91 or higher, or a re-
search octane number of 95 or high-
er. If knocking (or pinging) occurs,
use a gasoline of a different brand.
• For refueling, be sure to stop the
engine and use enough care not
to spill any fuel. Also be sure to
avoid refueling close to a fire.
• Refuel after the engine, exhaust
pipe, etc. have cooled off.
Gasohol (For USA and Canada)
There are two types of gasohol: gas-
ohol containing ethanol and that con-
taining methanol. Gasohol containing
ethanol can be used if the ethanol
content does not exceed 10%. Gaso-
hol containing methanol is not recom-
mended by Yamaha because it can
cause damage to the fuel system or
vehicle performance problems.
HANDLING NOTE
Never start or run the engine in a
closed area. The exhaust fumes
are poisonous; they can cause
loss of consciousness and death
in a very short time. Always oper-
ate the machine in a well-ventilated
area.
Recommended fuel:
Premium unleaded
gasoline only

1-18
STARTING AND BREAK-IN
• Unlike a two-stroke engine, this
engine cannot be kick started
when the throttle is open be-
cause the kickstarter may kick
back. Also, if the throttle is open
the air/fuel mixture may be too
lean for the engine to start.
• Before starting the machine, per-
form the checks in the pre-opera-
tion check list.
AIR FILTER MAINTENANCE
According to "CLEANING THE AIR
FILTER ELEMENT" section in the
CHAPTER 3, apply the foam-air-filter
oil or its equivalent to the element.
(Excess oil in the element may ad-
versely affect engine starting.)
STARTING A COLD ENGINE
1. Inspect the coolant level.
2. Shift the transmission into neutral.
3. Pull the starter knob/ idle screw
"1" to its full length.
Use the starter knob/ idle screw be-
low an air temperature of 15°C
(59°F).
4. Push the kickstarter down lightly
with your foot until resistance is
felt.
5. With the throttle fully closed, fold
out the kickstarter lever, move it
down lightly with your foot until the
gears engage, and then push it
down smoothly but forcefully.
Do not open the throttle while kick-
ing the kickstarter crank. Other-
wise, the kickstarter crank may
kick back.
If the engine fails to start, give the
kickstarter 10 to 20 slow kicks at full
throttle in order to clear the engine of
the rich air-fuel mixture retained in it.
6. When the engine starts running,
warm it up one or two minutes at
a steady speed (of 3,000 to 5,000
r/min), and then return the starter
knob/ idle screw to its original po-
sition.
7. Push the engine stop switch "1".
Do not warm up the engine for ex-
tended periods of time.
STARTING A WARM ENGINE
To start a warm engine, make sure
that the starter (choke) knob/idling
screw is pushed in and the throttle is
closed, and then start the engine by
pushing the kickstarter.
If the engine fails to start, give the
kickstarter 10 to 20 slow kicks at full
throttle in order to clear the engine of
the rich air-fuel mixture retained in it.
BREAK-IN PROCEDURES
1. Before starting the engine, fill the
fuel tank with the fuel.
2. Perform the pre-operation checks
on the machine.
3. Start and warm up the engine.
Check the idle speed, and check
the operation of the controls and
the engine stop switch. Then, re-
start the engine and check its op-
eration within no more than 5
minutes after it is restarted.
4. Operate the machine in the lower
gears at moderate throttle open-
ings for five to eight minutes.
5. Check how the engine runs when
the machine is ridden with the
throttle 1/4 to 1/2 open (low to me-
dium speed) for about one hour.6. Restart the engine and check the
operation of the machine through-
out its entire operating range. Re-
start the machine and operate it
for about 10 to 15 more minutes.
The machine will now be ready to
race.
• After the break-in or before each
race, you must check the entire
machine for loose fittings and
fasteners as per "TORQUE-
CHECK POINTS". Tighten all
such fasteners as required.
• When any of the following parts
have been replaced, they must
be broken in.
CYLINDER AND CRANKSHAFT:
About one hour of break-in oper-
ation is necessary.
PISTON, RING, VALVES, CAM-
SHAFTS AND GEARS:
These parts require about 30
minutes of break-in operation at
half-throttle or less. Observe the
condition of the engine carefully
during operation.

1-20
CLEANING AND STORAGE
CLEANING AND STORAGE
CLEANING
Frequent cleaning of your machine
will enhance its appearance, maintain
good overall performance, and ex-
tend the life of many components.
1. Before washing the machine,
block off the end of the exhaust
pipe to prevent water from enter-
ing. A plastic bag secured with a
rubber band may be used for this
purpose.
2. If the engine is excessively
greasy, apply some degreaser to
it with a paint brush. Do not apply
degreaser to the chain, sprockets,
or wheel axles.
3. Rinse the dirt and degreaser off
with a garden hose; use only
enough pressure to do the job.
Do not use high-pressure washers
or steam-jet cleaners since they
cause water seepage and deterio-
ration seals.
4. After the majority of the dirt has
been hosed off, wash all surfaces
with warm water and a mild deter-
gent. Use an old toothbrush to
clean hard-to-reach places.
5. Rinse the machine off immediate-
ly with clean water, and dry all
surfaces with a soft towel or cloth.
6. Immediately after washing, re-
move excess water from the
chain with a paper towel and lubri-
cate the chain to prevent rust.
7. Clean the seat with a vinyl uphol-
stery cleaner to keep the cover
pliable and glossy.
8. Automotive wax may be applied
to all painted or chromed surfac-
es. Avoid combination cleaner-
waxes, as they may contain abra-
sives.
9. After completing the above, start
the engine and allow it to idle for
several minutes.STORAGE
If your machine is to be stored for 60
days or more, some preventive mea-
sures must be taken to avoid deterio-
ration. After cleaning the machine
thoroughly, prepare it for storage as
follows:
1. Fill up the fuel tank and add fuel
stabilizer (if available) to prevent
the fuel tank from rusting and the
fuel from deteriorating.
2. Remove the spark plug, pour a ta-
blespoon of SAE 10W-40 motor
oil in the spark plug hole, and re-
install the plug. With the engine
stop switch pushed in, kick the en-
gine over several times to coat the
cylinder walls with oil.
3. Remove the drive chain, clean it
thoroughly with solvent, and lubri-
cate it. Reinstall the chain or store
it in a plastic bag tied to the frame.
4. Lubricate all control cables.
5. Block the frame up to raise the
wheels off the ground.
6. Tie a plastic bag over the exhaust
pipe outlet to prevent moisture
from entering.
7. If the machine is to be stored in a
humid or salt-air environment,
coat all exposed metal surfaces
with a film of light oil. Do not apply
oil to rubber parts or the seat cov-
er.
Make any necessary repairs before
the machine is stored.

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)

2-12
TIGHTENING TORQUES
*1: Tighten the cylinder head bolts to 30 Nm (3.0 m•kg, 22 ft•lb) in the proper tightening sequence, remove and retighten
the cylinder head bolts to 20 Nm (2.0 m•kg, 14 ft•lb) in the proper tightening sequence, and then tighten the cylinder head
bolts further to reach the specified angle 150° in the proper tightening sequence.
Oil filter element cover M6 2 10 Nm (1.0 m•kg, 7.2 ft•lb)
Oil pressure check bolt M6 2 10 Nm (1.0 m•kg, 7.2 ft•lb)
Crankshaft end accessing screw M36 1 10 Nm (1.0 m•kg, 7.2 ft•lb)
Timing mark accessing screw M14 1 6 Nm (0.6 m•kg, 4.3 ft•lb)
Clutch cover M6 7 10 Nm (1.0 m•kg, 7.2 ft•lb)
Right crankcase cover M6 9 10 Nm (1.0 m•kg, 7.2 ft•lb)
Left crankcase cover M6 8 10 Nm (1.0 m•kg, 7.2 ft•lb)
Crankcase M6 13 12 Nm (1.2 m•kg, 8.7 ft•lb)
Clutch cable holder M6 2 10 Nm (1.0 m•kg, 7.2 ft•lb)
Oil drain bolt M8 1 20 Nm (2.0 m•kg, 14 ft•lb)
Oil drain bolt M8 1 20 Nm (2.0 m•kg, 14 ft•lb)
Oil check bolt (crankcase) M6 1 10 Nm (1.0 m•kg, 7.2 ft•lb)
Oil strainer M6 1 10 Nm (1.0 m•kg, 7.2 ft•lb)
Oil nozzle M5 1 8 Nm (0.8 m•kg, 5.8 ft•lb)
Crankcase bearing stopper M6 8 10 Nm (1.0 m•kg, 7.2 ft•lb)
Crankcase bearing stopper (crankshaft) M8 4 22 Nm (2.2 m•kg, 16 ft•lb) Stake.
Drive axle oil seal stopper M6 2 10 Nm (1.0 m•kg, 7.2 ft•lb)
Kick shaft ratchet wheel guide M62 12 Nm (1.2 m•kg, 8.7 ft•lb)Lock washer
Kickstarter crank M8 1 33 Nm (3.3 m•kg, 24 ft•lb)
Screw (kickstarter crank) M6 1 7 Nm (0.7 m•kg, 5.1 ft•lb)
Primary drive gear M20 1 100 Nm (10.0 m•kg, 72 ft•lb)
Clutch boss M20 1 75 Nm (7.5 m•kg, 54 ft•lb)
Clutch cable locknut M8 1 7 Nm (0.7 m•kg, 5.1 ft•lb)
Clutch cable adjust bolt and locknut M6 1 4 Nm (0.4 m•kg, 2.9 ft•lb)
Clutch spring M6 6 10 Nm (1.0 m•kg, 7.2 ft•lb)
Balancer M10 1 45 Nm (4.5 m•kg, 32 ft•lb) Lock washer
Balancer shaft driven gear M14 1 50 Nm (5.0 m•kg, 36 ft•lb) Lock washer
Balancer weight M6 3 10 Nm (1.0 m•kg, 7.2 ft•lb)
Drive sprocket M20 1 75 Nm (7.5 m•kg, 54 ft•lb) Lock washer
Drive chain sprocket cover M6 27 Nm (0.7 m•kg, 5.1 ft•lb)
Shift pedal M6 1 12 Nm (1.2 m•kg, 8.7 ft•lb)
Shift guide M6 2 10 Nm (1.0 m•kg, 7.2 ft•lb)
Stopper lever M6 1 10 Nm (1.0 m•kg, 7.2 ft•lb)
Segment M8 1 30 Nm (3.0 m•kg, 22 ft•lb)Item
Thread
sizeQ'ty Tightening torque Remarks

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)

3-9
ENGINE
8. Apply:
• Foam-air-filter oil or equivalent oil
to the element
Squeeze out the excess oil. Element
should be wet but not dripping.
9. If the thin sheet (air filter element
2) is dirty with mud etc., clean the
thin sheet (air filter element 2) by
the following steps.
Cleaning steps:
a. Remove the air filter element 2
"1".
b. Clean the air filter element 2 with
solvent.
After cleaning, remove the remaining
solvent by squeezing the element.
Do not twist the element when
squeezing the element.
c. Inspect the air filter element 2.
Damage → Replace.
d. Install the air filter element 2.
10. Install:
• Air filter element "1"
• Air filter guide "2"
•Binder
11. Install:
• Mounting bolt for air filter case
cover12. Install:
• Fuel tank bolt (front)
CHECKING THE THROTTLE BODY
JOINT
1. Remove:
•Seat
• Air scoop (left/right)
•Fuel tank
• Air filter
2. Check:
• Throttle body joint "1"
Cracks/damage → Replace.
3. Install:
• Air filter
•Fuel tank
• Air scoop (left/right)
•Seat
CHECKING THE FUEL LINE
1. Remove:
•Seat
•Fuel tank
• Air scoop (left/right)
• Air filter case
• Cover
2. Check:
• Fuel hose "1"
Cracks/damage → Replace.
Loose connection → Reconnect.
3. Install:
• Cover
• Air filter case
• Air scoop (left/right)
•Fuel tank
•Seat
CHECKING THE ENGINE OIL
LEVEL
1. Stand the machine on a level sur-
face.
• When checking the oil level make
sure that the machine is upright.
• Place the machine on a suitable
stand.
2. Start the engine, warm it up for
2–3 minutes at engine idling
speed, and then stop the engine
and wait approximately 1 minute.
3. Inspect:
• Oil level
Make sure that the engine oil level
is between the maximum level
line "a" and minimum level line "b"
shown for the oil level check win-
dow.
Above the upper limit "a"→Check
that no oil comes out when the
check bolt "1" for the oil quantity
upper limit is removed.
If any engine oil comes out, drain
it until its last drop is out.
Below the level mark "b"→Add
sufficient oil and idle run the en-
gine, and after stopping the en-
gine, recheck through the oil
inspection window that the oil is at
the specified level.
• Check the oil quantity within 5 min-
utes after the engine is shut off.
Over 5 minutes, idle the engine
again and recheck the oil quantity.
• Do not leave the check bolt for the
oil quantity upper limit removed.
Otherwise, the oil level drops with
time in the engine, allowing the oil
to flow out.
• Engine oil also luburicates the
clutch and the wrong oil types or
additives could cause clutch
slippage. Therefore, do not add
any chemical additives or use en-
gine oils with a grade of CD or
higher and do not use oils la-
beled "ENERGY CONSERVING
II".
• Do not allow foreign material to
enter the crankcase.
Oil application quantify:
35 g
Mounting bolt for air filter
case cover:
5 Nm (0.5 m•kg, 3.6
ft•lb)
Fuel tank bolt (front):
9 Nm (0.9 m•kg, 6.5
ft•lb)