YAMAHA YFZ450 2012 Service Manual

4-16
4
TIP
A special wrench can be obtained at a Yamaha
dealer to make this adjustment.
The spring preload setting is determined by
measuring distance A, shown in the illustration.
The shorter distance A is, the higher the spring
preload; the longer distance A is, the lower the
spring preload. With each complete turn of the
adjusting nut, distance A is changed by 1.5 mm
(0.06 in).
7. Tighten the locknut to the specified torque.NOTICE: Always tighten the locknut
against the adjusting nut, and then tighten
it to the specified torque.
[ECB00081]
1. Spring preload adjusting nut
2. Locknut
3. Special wrench
2
1
(a)
(b)3
Spring preload setting:
Minimum (soft):Distance A = 265.0 mm (10.43 in)
Standard: Distance A = 257.0 mm (10.12 in)
Maximum (hard): Distance A = 250.0 mm (9.84 in)1. Distance A
1
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4-17
48. Place the air filter case in the original position,
connect the air intake duct, and then tighten
the clamp screw at the carburetor side.
NOTICE: Make sure that the air intake duct
is properly connected to the carburetor,
and that the clamp screw is tightened se-
curely.
[ECB01170]
9. Install the bolts, install the hose joint, and then connect the hoses.
10. Install the seat.
WARNING
EWB00450This shock absorber assembly contains highly
pressurized nitrogen gas. If the shock absorb-
er assembly is damaged, it could explode
causing injury or property damage. Shock ab-
sorber cylinder damage could also result in
poor handling which could cause an accident.
Do not tamper with or attempt to open the
cylinder assembly.
Do not subject the shock absorber assembly
to an open flame or other high heat.

Do not deform or damage the cylinder in any
way.
Do not dispose of a damaged or worn out
shock absorber assembly yourself. Take the
shock absorber assembly to a Yamaha deal-
er for any service.
Tightening torque: Locknut:44 Nm (4.4 m ·kgf, 32 ft· lbf)
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5-1
5
EBU19201
PRE-OPERATION CHECKS
EBU19224Inspect your vehicle each time you use it to make sure the vehicle is in safe operating condition. Always
follow the inspection and maintenance procedures and schedules described in the Owner’s Manual.
WARNING
EWB00481Failure to inspect or maintain the vehicle properly increases the possibility of an accident or equip-
ment damage. Do not operate the vehicle if you find any problem. If a problem cannot be corrected
by the procedures provided in this manual, have the vehicle inspected by a Yamaha dealer.Before using this vehicle, check the following points:
ITEM ROUTINE PAGE
Fuel 
Check fuel level in fuel tank, and add recommended fuel if neces-
sary.
 Check fuel line for leakage. Correct if necessary. 4-8, 5-4
Engine oil 
Check oil level in engine oil tank, and add recommended oil to spec-
ified level if necessary.
 Check ATV for oil leakage. Correct if necessary. 5-4, 8-14
Coolant 
Check coolant level in reservoir, and add recommended coolant to
specified level if necessary.
 Check cooling system for leakage. Correct if necessary. 5-4, 8-20
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5-2
5
Front brake
Check operation. If soft or spongy, have Yamaha dealer bleed hy-
draulic system.
 Check brake pads for wear, and replace if necessary.
 Check brake fluid level in reservoir, and add specified brake fluid to
specified level if necessary.
 Check hydraulic system for leakage. Correct if necessary. 5-4, 8-32, 8-33, 8-36
Rear brake 
Check operation. If soft or spongy, have Yamaha dealer bleed hy-
draulic system.
 Check brake pads for wear, and replace if necessary.
 Check brake fluid level in reservoir, and add specified brake fluid to
specified level if necessary.
 Check hydraulic system for leakage. Correct if necessary. 5-4, 8-32, 8-33, 8-36
Clutch 
Check operation, and correct if necessary.
 Lubricate cable if necessary.
 Check lever free play, and adjust if necessary. 8-39
Throttle lever 
Make sure that operation is smooth. Lubricate cable and lever hous-
ing if necessary.
 Check lever free play, and adjust if necessary. 5-5, 8-31
Control cables Make sure that operation is smooth. Lubricate if necessary. 8-43
Drive chain 
Check chain slack, and adjust if necessary.
 Check chain condition. Lubricate if necessary. 5-5, 8-41, 8-43
Wheels and tires 
Check wheel condition, and replace if damaged.
 Check tire condition and tread depth. Replace if necessary.
 Check air pressure. Correct if necessary. 5-5
Shift pedal 
Make sure that operation is smooth.
 Correct if necessary. 8-45
Brake pedal 
Make sure that operation is smooth. Lubricate pedal pivoting point if
necessary. 8-45
ITEM ROUTINE PAGEU1PD60E0.book Page 2 Monday, June 13, 2011 2:57 PM

5-3
5
Brake and clutch levers
Make sure that operation is smooth. Lubricate lever pivoting points if
necessary. 8-44
Chassis fasteners Make sure that all nuts, bolts and screws are properly tightened. 5-7
Instruments, lights and
switches 
Check operation, and correct if necessary. 5-7
ITEM ROUTINE PAGE
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5-4
5
EBU19541Fuel Make sure that there is sufficient fuel in the tank.
(See page 4-8.)EBU19560Engine oil Make sure that the engine oil is at the specified lev-
el. Add oil as necessary. (See page 8-14.)EBU19631Coolant Make 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.EBU19712Front and rear brakes Brake 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
8-36.) 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 system.
Brake fluid level
Check the brake fluid level. Add fluid if necessary.
(See page 8-33.)
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.
Brake 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 8-32.) Specified brake fluid:
DOT 4
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5-5
5
EBU19761Throttle lever Check 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.EBU19770Drive chain Check the condition of the drive chain and check
the drive chain slack. Lubricate and adjust the
drive chain as necessary. (See page 8-41.)EBU19794Tires Check tire pressure regularly to make sure it is at
the recommended specifications. Also check for
wear and damage.
Tire pressure
Use the low-pressure tire gauge to check and ad-
just tire pressures when the tires are cold. Tire
pressures 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.
[EWB02541]
Set tire
pressures to the following specifications:
The low-pressure tire gauge is included as stan-
dard equipment. Make two measurements of the
tire pressure and use the second reading. Dust or
dirt in the gauge could cause the first reading to be
incorrect. Recommended tire pressure:
Fron t25.0 kPa (0.250 kgf/cm ², 3.6 psi)
Rear 30.0 kPa (0.300 kgf/cm ², 4.4 psi)
Minimum tire pressure: Fron t22.0 kPa (0.220 kgf/cm ², 3.2 psi)
Rear 27.0 kPa (0.270 kgf/cm ², 4.0 psi)
Maximum tire seating pressure: Fron t250 kPa (2.5 kgf/cm² , 36 psi)
Rear 250 kPa (2.5 kgf/cm² , 36 psi)
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5-6
5Tire wear limit
When the tire groove decreases to 3 mm (0.12 in)
due to wear, replace the tire. Tire information
This ATV is equipped with tubeless tires with
valves.
WARNING
EWB02551Use of improper tires on this ATV may cause
loss of control, increasing your risk of an acci-
dent.After extensive tests, only the tires listed below
have been approved for this model by Yamaha
Motor Co., Ltd.
1. Low-pressure tire gauge
1
1. Tire wear limit
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5-7
5
Aftermarket 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.
EBU19840Chassis fasteners Make sure that all nuts, bolts and screws are prop-
erly tightened.
EBU19850Instruments, lights and switches Check that all instruments, lights and switches are
working properly. Correct if necessary.
Fro nt:
Manufacturer/model:DUNLOP/KT851B Bias
Size: AT21 x 7-10
Ty p e : Tu b e l e s s
Rear: Manufacturer/model:DUNLOP/KT355A Radial
Size: AT20 x 10R9
Ty p e : Tu b e l e s s
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6-1
6
EBU19881
OPERATION
EBU19901Read 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
EWB00631Read 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.EBU20184Starting a cold engine NOTICEECB00150See the “Engine break-in ” section on page 6-5
prior to operating the engine for the first time.1. Set the parking brake.
2. Turn the fuel cock to “ON ”.
3. Turn the key to “ON ” and the engine stop
switch to “”. 4. Shift the transmission into neutral. The neutral
indicator light should come on. If the indicator
light does not come on, have a Yamaha deal-
er 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.5. Use the starter (choke) in reference to the fig-ure:
Position (1):
Cold engine start with ambient temperature
below 5 ° C (40 °F).
Position (2):
Cold engine start with ambient temperature
between 0 ° C (30 °F) and 30 ° C (90 °F).
Position (3):
Cold engine start with ambient temperature
above 25 °C (80 °F).
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