2012 YAMAHA YFZ450 maintenance

8-14
8To install the spark plug
1. Clean the surface of the spark plug gasket and its mating surface, and then wipe off any
grime from the spark plug threads.
2. Install the spark plug with the spark plug wrench, and then tighten it to the specified
torque.
TIPIf a torque wrench is not available when installing
the spark plug, a good estimate of the correct
torque is 1/4 –1/2 turn past finger tight. However,
the spark plug should be tightened to the specified
torque as soon as possible.3. Install the spark plug cap.
4. Place the fuel tank in the original position, and then install the bolt.
5. Remove the fuel tank cap by turning it coun- terclockwise.
6. Place the panel in the original position. 7. Install the fuel tank cap by turning it clockwise.
8. Install the bolts and the quick fastener screws.
9. Install the seat.
EBU23307Engine oil and oil filter element The engine oil level should be checked before
each ride. In addition, the oil must be changed and
the oil filter element replaced at the intervals spec-
ified in the periodic maintenance and lubrication
chart.
Tightening torque:
Spark plug:13 Nm (1.3 m ·kgf, 9.4 ft ·lbf)1. Projection
2. Slot
2 1
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8a higher quality than specified. In addition,
do not use oils labeled
“ENERGY CONSERV-
ING II” or higher.

Make sure that no foreign material enters the
crankcase.15. Start the engine, and then let it idle for several
minutes while checking it for oil leakage. If oil
is leaking, immediately turn the engine off and
check for the cause.
16. Turn the engine off, and then check the oil lev- el and correct it if necessary.
17. Install the engine guard by installing the bolts, and then tighten them to the specified torque.
NOTICE: Be sure to apply LOCTITE
® to the
engine guard bolts before installing them.
[ECB00371] EBU23470
Coolant The coolant level should be checked before each
ride. In addition, the coolant must be changed at
the intervals specified in the periodic maintenance
and lubrication chart.EBU27942To check the coolant level
1. Place the ATV on a level surface.TIPThe coolant level must be checked on a cold en-
gine since the level varies with engine tempera-
ture.2. Check the coolant level in the coolant reser- voir.TIPThe coolant should be between the minimum and
maximum level marks.
Tightening torque:Engine guard bolt:7 Nm (0.7 m ·kgf, 5.1 ft ·lbf)
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8-24
813. Remove the radiator cap to check the coolant
level in the radiator. If it is low, add sufficient
coolant until it reaches the top of the radiator,
and then install the radiator cap.
14. Start the engine, and then check for coolant leakage.
TIPIf any leakage is found, have a Yamaha dealer
check the cooling system.15. Install the panel.EBU23707Cleaning the air filter element The air filter element should be cleaned at the in-
tervals specified in the periodic maintenance and
lubrication chart. Clean or, if necessary, replace
the air filter element more frequently if you are
riding in unusually wet or dusty areas.TIPThere is a check hose at the bottom of the air filter
case. If dust or water collects in this hose, empty
the hose and clean the air filter element and air fil-
ter case.
1. Place the ATV on a level surface.
2. Remove the seat. (See page 4-12.)
3. Remove the air filter case cover by unhookingthe holders.1. Air filter case check hose
1
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8-28
817. Install the seat.
TIPThe air filter element should be cleaned every 20
–
40 hours. It should be cleaned and lubricated more
often if the ATV is operated in extremely dusty ar-
eas. Each time the air filter element maintenance
is performed, check the air inlet of the air filter case
for obstructions. Check the air filter case rubber
joint to the carburetor fittings and the rubber joint
manifold fittings for an air-tight seal. Tighten all fit-
tings securely to avoid the possibility of unfiltered
air entering the engine.EBU27703Cleaning the spark arrester Select a well-ventilated area free of combustible
materials and make sure the exhaust and muffler
are cool. 1. Remove the tailpipe bolt. 2. Remove the tailpipe by pulling it out of the
muffler.
3. Tap the tailpipe lightly, and then use a wire brush to remove any carbon deposits from the
spark arrester portion of the tailpipe and inside
of the tailpipe housing.
1. Tailpipe bolt
1
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8-30
8
WARNING
EWB02380Never run the engine in an enclosed area when
purging the spark arrester, otherwise it could
cause injury to the eyes, burns, carbon monox-
ide poisoning, possibly leading to death, and
start a fire.
Always let the exhaust system cool prior to
touching exhaust components.
Always wear eye protection, and make sure
no one is behind the ATV.
Make sure there are no combustible materi-
als in the area.EBU23940Adjusting the carburetor The carburetor should be checked and, if neces-
sary, adjusted at the intervals specified in the peri-
odic maintenance and lubrication chart. The
carburetor is an important part of the engine and
requires very sophisticated adjustment. Therefore,
most carburetor adjustments should be left to aYamaha dealer, who has the necessary profes-
sional knowledge and experience. The adjustment
described in the following section, however, may
be performed by the owner as part of routine main-
tenance.
NOTICEECB00480The carburetor has been set and extensively
tested at the Yamaha factory. Changing these
settings without sufficient technical knowl-
edge may result in poor performance of or
damage to the engine.EBU24030Checking the engine idling speed A special tester is needed to check the engine
idling speed on this model.
Therefore, take the ATV to a Yamaha dealer to
have the engine idling speed checked and adjust-
ed.
Tightening torque:
Purging bolt:27 Nm (2.7 m ·kgf, 20 ft· lbf)Engine idling speed:
1750 –1850 r/min
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8-31
8
EBU24047Adjusting the throttle lever free play The throttle lever free play should be checked and,
if necessary, adjusted at the intervals specified in
the periodic maintenance and lubrication chart.
The throttle lever free play should measure 2.0–
4.0 mm (0.08 –0.16 in) as shown. Periodically
check the throttle lever free play and, if necessary,
adjust it as follows.TIPThe engine idling speed must be checked, and ad-
justed if necessary, before adjusting the throttle le-
ver free play.1. Slide the rubber cover back.
2. Loosen the locknut.
3. To increase the throttle lever free play, turn the throttle lever free play adjusting bolt in di-
rection (a). To decrease the throttle lever free
play, turn the adjusting bolt in direction (b). 4. Tighten the locknut.
5. Slide the rubber cover to its original position.
EBU24060Valve clearance The valve clearance changes with use, resulting in
improper air-fuel mixture and/or engine noise. To
prevent this from occurring, the valve clearance
must be adjusted by a Yamaha dealer at the inter-
vals specified in the periodic maintenance and lu-
brication chart.1. Rubber cover
2. Throttle lever free play adjusting bolt
3. Locknut
4. Throttle lever free play
4
2
1
3
(a)
(b)
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8
5. Install the brake fluid reservoir bracket bolt.
6. Install the seat.
WARNING
EWB02720Improper maintenance can result in loss of
braking ability. Observe these precautions:

Insufficient brake fluid may allow air to enter
the brake system, reducing braking perfor-
mance.
Clean the filler cap before removing. Use
only DOT 4 brake fluid from a sealed contain-
er.
Use only the specified brake fluid; otherwise,
the rubber seals may deteriorate, causing
leakage.
Refill with the same type of brake fluid. Add-
ing a brake fluid other than DOT 4 may result
in a harmful chemical reaction.
Be careful that water does not enter the
brake fluid reservoir when refilling. Water
will significantly lower the boiling point of
the fluid and may result in vapor lock.NOTICEECB01160Brake fluid may damage painted surfaces or
plastic parts. Always clean up spilled fluid im-
mediately.As the brake pads wear, it is normal for the brake
fluid level to gradually go down. A low brake fluid
level may indicate worn brake pads and/or brake
system leakage; therefore, be sure to check the
1. Frame
2. Projection
3. Brake fluid reservoir bracket
4. BoltSpecified brake fluid:
DOT 4
2 3
1 4
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8brake pads for wear and the brake system for leak-
age. If the brake fluid level goes down suddenly,
have a Yamaha dealer check the cause before fur-
ther riding.
EBU24291Changing the brake fluid Have a Yamaha dealer change the brake fluid at
the intervals specified in the TIP after the periodic
maintenance and lubrication chart. In addition,
have the oil seals of the master cylinders and cali-
pers as well as the brake hoses replaced at the in-
tervals listed below or whenever they are damaged
or leaking.
Oil seals: Replace every two years.
Brake hoses: Replace every four years.EBU24394Checking the front brake lever free play The brake lever free play must be checked at the
intervals specified in the periodic maintenance and
lubrication chart. The brake lever should have no
free play as shown. If there is free play, have a
Yamaha dealer check the brake system.
EBU24613Checking the brake pedal height The brake pedal height must be checked and, if
necessary, adjusted at the intervals specified in the
periodic maintenance and lubrication chart.
The top of the brake pedal should be positioned
11.7 mm (0.46 in) below the top of the footrest as
shown. If the brake pedal is not positioned as spec-
ified, have a Yamaha dealer adjust it.1. No brake lever free play
1
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