YAMAHA YFZ450 2019 Workshop Manual

5-4
5
EBU38000FuelMake sure there is sufficient gasoline in the tank
before starting off. Refuel if necessary. (See page
4-9.)EBU19561Engine oilMake sure that the engine oil is at the specified
level. Add oil as necessary. (See page 8-14.)EBU19632CoolantMake sure that the coolant is at the specified level.
Add coolant as necessary. (See page 8-20.)TIPThe coolant level must be checked on a cold en-
gine since the level varies with engine tempera-
ture. EBU19713Front and rear brakesBrake lever and brake pedal
Check that there is no free play in the brake le-
ver. If there is free play, have a Yamaha dealer
check the brake system. 
Check for correct brake pedal height. (See page
8-32.) If the pedal height is incorrect, have a
Yamaha dealer adjust it.
 Check the operation of the lever and pedal.
They should move smoothly and there should
be a firm feeling when the brakes are applied. If
not, have a Yamaha dealer check the brake sys-
tem.
Brake fluid level
Check the brake fluid level. Add fluid if necessary.
(See page 8-30.)
Brake fluid leakage
Check to see if any brake fluid is leaking out of the
pipe joints or brake fluid reservoirs. Apply the
brakes firmly for one minute. If there is any leak-
age, have a Yamaha dealer check the brake sys-
tem. Specified brake fluid:
DOT 4UBW262E0.book Page 4 Tuesday, April 3, 2018 10:59 AM

5-5
5Brake operation
Test the brakes at slow speed after starting out to
make sure they are working properly. If the brakes
do not provide proper braking performance,
check the brake pads for wear. (See page 8-29.)
EBU19762Throttle leverCheck the operation of the throttle lever. It must
open smoothly and spring back to the idle position
when released. Have a Yamaha dealer correct if
necessary.EBU19771Drive chainCheck the condition of the drive chain and check
the drive chain slack. Lubricate and adjust the
drive chain as necessary. (See page 8-36.)EBU19818TiresCheck tire pressure regularly to make sure it is at
the recommended specifications. Also check for
wear and damage. Tire pressure
Use a tire pressure gauge to check and adjust tire
air pressure when the tires are cold. The tire air
pressure must be equal on both sides.
WARNING! Operation of this vehicle with im- proper tire pressure may cause severe injury or
death from loss of control or rollover. Tire
pressure below the minimum specified could
also cause the tire to dislodge from the rim un-
der severe riding conditions.
[EWB02542]
Recommended tire pressure: Front35.0 kPa (0.350 kgf/cm², 5.0 psi)
Rear 35.0 kPa (0.350 kgf/cm², 5.0 psi)
Minimum tire pressure: Front32.0 kPa (0.320 kgf/cm², 4.6 psi)
Rear 32.0 kPa (0.320 kgf/cm², 4.6 psi)
Maximum tire seating pressure: Front250 kPa (2.5 kgf/cm², 36 psi)
Rear 250 kPa (2.5 kgf/cm², 36 psi)
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5
Tire pressure gauge
A low-pressure tire gauge is included as standard
equipment with your vehicle. (See page 8-2.)
When using the tire pressure gauge, make two
measurements and use the second reading as grit
in the gauge or tire valve could have caused the
first reading to be incorrect.
Tire wear
If the tire is damaged or the tire tread depth de-
creases to 3 mm (0.12 in) or less, replace the tire. Tire information
This ATV is equipped with tubeless tires and tire
air valves. After extensive tests, only the tires list-
ed below are approved for this model by Yamaha.
WARNING
EWB02552Use of improper tires on this ATV may cause
loss of control, increasing your risk of an acci-
dent.
1. Low-pressure tire gauge
2. Tire air valve
1
2
1. Tire tread depth
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5-7
5Aftermarket tires and rims
The tires and rims that came with your ATV were
designed to match the performance capabilities
and to provide the best combination of handling,
braking, and comfort. Other tires, rims, sizes, and
combinations may not be appropriate.
EBU19841Chassis fastenersMake sure that all nuts, bolts and screws are
properly tightened.EBU19851Instruments, lights and switchesCheck that all instruments, lights and switches are
working properly. Correct if necessary.Front:
Manufacturer/model:MAXXIS/MS21
Size: AT21 x 7R10
Rear: Manufacturer/model:MAXXIS/MS22
Size: AT20 x 10R9UBW262E0.book Page 7 Tuesday, April 3, 2018 10:59 AM

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6
EBU19882
OPERATION
EBU19902Read the Owner’s Manual carefully before riding
the ATV. If there is a control or function you do not
understand, ask your Yamaha dealer.
WARNING
EWB00632Read the Owner’s Manual carefully to become
familiar with all controls in order to help pre-
vent any loss of control, which could cause an
accident or injury. EBU29954Starting the engineNOTICEECB00151See the “Engine break-in” section on page 6-4
prior to operating the engine for the first time. 1. Set the parking brake.
2. Turn the key to “ ” (on) and the engine stopswitch to “ ”.
The following warning lights should come on
for a few seconds, then go off. 
Coolant temperature warning light
 Fuel level warning light
 Engine trouble warning light
NOTICEECB00826To avoid possible damage, do not operate the
ATV if a warning light does not work as de-
scribed above. 3. Shift the transmission into neutral. The neutral
indicator light should come on, if it does not
come on, have a Yamaha dealer check the
electrical circuit.TIPThis model is equipped with an ignition circuit cut-
off system. The engine can be started under the
following conditions.
The transmission is in neutral.
 The clutch is disengaged with the transmission
in gear. However, it is recommended to shift
into neutral before starting the engine. 4. Completely close the throttle lever and start
the engine by pushing the start switch.
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6
TIPIf the engine fails to start, release the start switch,
then push it again. Pause a few seconds before
the next attempt. Each cranking should be as
short as possible to preserve battery energy. Do
not crank the engine more than 10 seconds on
each attempt. NOTICEECB00164For maximum engine life, never accelerate
hard when the engine is cold! EBU20525ShiftingThis ATV has a 5-speed forward transmission. The
transmission allows you to control the amount of
power you have available at a given speed or for
starting, accelerating, climbing hills, etc.
To shift into neutral, release the throttle lever, ap-
ply the clutch, and then repeatedly depress the
shift pedal until it stops.
When it stops, it will be in first gear. Raise the ped-
al slightly to reach the neutral position, and then
release the clutch.
EBU20595To start out and accelerate1. Release the throttle lever, apply the front or rear brake, and then release the parking
brake.
2. Pull the clutch lever to disengage the clutch.
3. Shift into first gear, and then release the brake. NOTICE: Always close the throttle
before shifting gears, otherwise damage
to the engine and drive train may result.
[ECB01220]
1. Shift pedal
2. Neutral position
1
1
N
2 3
4
5
2
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6
4. Open the throttle gradually and at the same
time, release the clutch lever slowly.
WARNING! Opening the throttle abruptly or releasing the clutch lever too quickly
could make the ATV wheelie, which would
increase the chance of an accident, in-
cluding an overturn.
[EWB00732]
5. Once the ATV has attained adequate speed, release the throttle, and at the same time,
quickly pull in the clutch lever.
6. Shift the transmission into second gear. (Make sure not to shift the transmission into
neutral.)
7. Open the throttle part way and gradually re- lease the clutch lever.
8. Follow the same procedure when shifting to the next higher gear.EBU20653To decelerate
When slowing down or stopping, release the
throttle and apply the brakes smoothly and evenly.
As you slow down, shift to a lower gear. Be sure
that the engine has sufficiently slowed before en-
gaging a lower gear. Improper use of the brakes or shifting can cause the tires to lose traction, reduc-
ing control and increasing the possibility of an ac-
cident.
WARNING
EWB00712Make sure the engine has sufficiently slowed
before shifting to a lower gear. Engaging a low-
er gear when the engine speed is too high
could make the wheels stop rotating and lose
traction. This could cause loss of control, an
accident and injury. It could also cause engine
or drivetrain damage. NOTICEECB00181
Even with the transmission in the neutral po-
sition, do not coast for long periods of time
with the engine off, and do not tow the ATV
for long distances. The transmission is prop-
erly lubricated only when the engine is run-
ning. Inadequate lubrication may damage
the transmission.
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6-4
6
Always use the clutch when changing gears.
The engine, transmission and drive train are
not designed to withstand the shock of
forced shifting and can be damaged by shift-
ing without using the clutch.
EBU20674Engine break-inThere is never a more important period in the life
of your engine than the first 320 km (200 mi) or 20
hours of operation. For this reason, you should fol-
low the engine break-in instructions carefully.
Since the engine is brand new, do not put an ex-
cessive load on it for the first 320 km (200 mi) or
20 hours. During this period the various parts in
the engine wear and polish themselves to the cor-
rect operating clearances. Avoid prolonged full-
throttle operation or any condition that might re-
sult in engine overheating.
0–160 km (0–100 mi) or 0–10 hours
Avoid prolonged operation above 1/2 throttle.
Vary the speed of the ATV regularly. Do not oper-
ate it at one set throttle position. 160–320 km (100–200 mi) or 10–20 hours
Avoid prolonged operation above 3/4 throttle. Rev
the engine through the gears freely, but do not use
full throttle at any time.
320 km (200 mi) or 20 hours and beyond
The ATV can now be operated normally.
NOTICEECB00221If any engine trouble should occur during the
engine break-in period, immediately have a
Yamaha dealer check the ATV. EBU26762ParkingWhen parking the ATV, shift into first gear, stop
the engine, and then apply the parking brake.
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6
EBU20907Parking on a slope
WARNING
EWB00852Avoid parking on hills or other inclines. Parking
on a hill or other incline could cause the ATV to
roll out of control, increasing the chance of an
accident. If you must park on an incline, place
the ATV transversely across the incline, shift
into first gear, stop the engine, apply the park-
ing brake, and then block the front and rear
wheels with rocks or other objects.Never park the ATV on hills that are too steep
to walk up easily.
1. Bring the ATV to a stop by applying the
brakes.
2. With the brake pedal applied, shift into first gear and then stop the engine.
3. Apply the parking brake.EBU20911Accessories and loadingEBU20922Genuine Yamaha Accessories
Choosing accessories for your ATV is an impor-
tant decision. Genuine Yamaha Accessories,
which are available only from a Yamaha dealer,
1. Parking brake lever (locked position)UBW262E0.book Page 5 Tuesday, April 3, 2018 10:59 AM

6-6
6have been designed, tested, and approved by
Yamaha for use on your ATV. Many companies with no connection to Yamaha manufacture parts
and accessories or offer other modifications for
Yamaha vehicles. Yamaha is not in a position to test the products that these aftermarket compa-
nies produce. Therefore, Yamaha can neither en-
dorse nor recommend the use of accessories not
sold by Yamaha or modifications not specifically
recommended by Yamaha, even if sold and in-
stalled by a Yamaha dealer.
Aftermarket parts, accessories, and modifica-
tions
While you may find aftermarket products similar in
design and quality to genuine Yamaha Accesso-
ries, recognize that some aftermarket accessories
or modifications are not suitable because of po-
tential safety hazards to you or others. Installing
aftermarket products or having other modifica-
tions performed to your ATV that change any of
the vehicle’s design or operation characteristics
can put you and others at greater risk of serious
injury or death. You are responsible for injuries re-
lated to changes in the vehicle. Keep the following in mind when considering an
accessory or operating an ATV which has acces-
sories.

Accessories should be rigidly and securely
mounted. An accessory which can shift position
or come off while you are riding could affect
your ability to control the ATV.
 Do not mount an accessory where it could inter-
fere with your ability to control the ATV. Exam-
ples include (but are not limited to) a heavy or
bulky object attached to the handlebars which
could make steering difficult, an accessory that
limits your ability to move around on the seat, or
one that limits your view.
 Use extra caution when riding an ATV with ac-
cessories. The ATV may handle differently than
it does without accessories.
EBU20942Loading
WARNING
EWB00821Never exceed the stated load capacity for this
ATV. Overloading this ATV or carrying or tow-
ing cargo improperly could cause changes in
ATV handling which could lead to an accident.
Cargo should be properly distributed and se-
UBW262E0.book Page 6 Tuesday, April 3, 2018 10:59 AM