YAMAHA YFZ450R 2011 Owners Manual

8-25
8 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.4. Insert the tailpipe into the muffler and align the
bolt holes.
5. Install the bolt and tighten it to the specified
torque.
6. Remove the purging bolt and the gasket.
1. Bolt
2. Tailpipe
1
2
1. Tailpipe
2. Spark arresterTightening torque:
Tailpipe bolt:
8 Nm (0.8 m·kgf, 5.8 ft·lbf)
1
2
U18P64E0.book Page 25 Thursday, May 13, 2010 6:00 PM

8-26
87. Start the engine and rev it up approximately
twenty times while momentarily creating ex-
haust system back pressure by blocking the
end of the muffler with a shop towel.
8. Stop the engine and allow the exhaust pipe to
cool.
9. Check the gasket for damage, and replace it if
necessary.
10. Install the gasket and the purging bolt, and
then tighten the bolt to the specified torque.
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.EBU29701Adjusting 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.
1. Purging bolt
2. Gasket
2
1
Tightening torque:
Purging bolt:
27 Nm (2.7 m·kgf, 20 ft·lbf)
U18P64E0.book Page 26 Thursday, May 13, 2010 6:00 PM

8-27
8 The throttle lever free play should measure 2.0–
4.0 mm (0.08–0.16 in) at the throttle lever. Period-
ically check the throttle lever free play and, if nec-
essary, adjust it as follows.
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.EBU29601Brakes Replacement of brake components requires pro-
fessional knowledge. Brake service should be per-
formed by a Yamaha dealer.
WARNING
EWB02571Operating with improperly serviced or adjust-
ed brakes could lead to a loss in braking ability
and an accident.EBU24130Checking the front and rear brake pads The front and rear brake pads must be checked for
wear at the intervals specified in the periodic main-
tenance and lubrication chart.
1. Rubber cover
2. Throttle lever free play adjusting bolt
3. Locknut
4. Throttle lever free play
3 2
4 (a)(b)
1
U18P64E0.book Page 27 Thursday, May 13, 2010 6:00 PM

8-28
8
EBU29560Front brake pads
Each brake pad is provided with wear indicator
grooves, which allow you to check the brake pad
wear without having to disassemble the brake. To
check the brake pad wear, check the wear indica-
tor grooves. If a brake pad has worn to the point
that the wear indicator grooves have almost disap-
peared, have a Yamaha dealer replace the brake
pads as a set.TIPThe wheels need to be removed to check the
brake pads. (See page 8-47.)
EBU29831Rear brake pads
Each brake pad is provided with wear indicator
grooves, which allow you to check the brake pad
wear without having to disassemble the brake. To
check the brake pad wear, check the wear indica-
tor grooves. If a brake pad has worn to the point
that the wear indicator grooves have almost disap-
peared, have a Yamaha dealer replace the brake
pads as a set.
1. Wear indicator groove
1
1. Wear indicator groove
1
U18P64E0.book Page 28 Thursday, May 13, 2010 6:00 PM

8-29
8
EBU29500Checking the brake fluid level Insufficient brake fluid may allow air to enter the
brake system, possibly causing it to become inef-
fective.
Before riding, check that the brake fluid is above
the minimum level mark and replenish if neces-
sary. A low brake fluid level may indicate worn
brake pads and/or brake system leakage. If the
brake fluid level is low, be sure to check the brake
pads for wear and the brake system for leakage.
Front brakeRear brake
TIPTo check the rear brake fluid level, remove the
seat. (See page 4-10.)Observe these precautions:
When checking the fluid level, make sure that
the top of the brake fluid reservoir is level.
Use only the recommended quality brake fluid,
otherwise the rubber seals may deteriorate,
causing leakage and poor braking performance.
1. Minimum level mark
1
1. Minimum level markRecommended brake fluid:
DOT 4
1
U18P64E0.book Page 29 Thursday, May 13, 2010 6:00 PM

8-30
8

Refill with the same type of brake fluid. Mixing
fluids may result in a harmful chemical reaction
and lead to poor braking performance.
Be careful that water does not enter the brake
fluid reservoir when refilling. Water will signifi-
cantly lower the boiling point of the fluid and may
result in vapor lock.
Brake fluid may deteriorate painted surfaces or
plastic parts. Always clean up spilled fluid imme-
diately.
As the brake pads wear, it is normal for the brake
fluid level to gradually go down. However, if the
brake fluid level goes down suddenly, have a
Yamaha dealer check the cause.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.1. No brake lever free play
1
U18P64E0.book Page 30 Thursday, May 13, 2010 6:00 PM

8-31
8 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.
EBU24712Adjusting the parking brake free play The parking brake free play must be checked and,
if necessary, adjusted at the intervals specified in
the periodic maintenance and lubrication chart.
Cable length “A” should measure 47–51 mm
(1.85–2.01 in). Adjust the parking brake free play
as follows.1. Release the parking brake by moving the
parking brake lever to the right.
2. Fully loosen the locknut and the adjusting bolt
at the rear brake caliper.
3. Slide the rubber cover back.
4. Loosen the locknut on the brake cable.
5. Turn the adjusting nut on the brake cable in di-
rection (a) to increase the cable length, and in
direction (b) to decrease it.1. Brake pedal height
1
1. Adjusting bolt
2. Cable length “A”
3. Locknut
1
2
3
U18P64E0.book Page 31 Thursday, May 13, 2010 6:00 PM

8-32
8
TIPIf the cable length cannot be adjusted to specifica-
tion, consult a Yamaha dealer.6. Tighten the locknut on the brake cable.
7. Slide the rubber cover to its original position.
8. Turn in the adjusting bolt at the rear brake cal-
iper until it feels tight, then turn it out 1/8 turn
and tighten its locknut to the specified torque.
NOTICE: When tightening the locknut,hold the adjusting bolt with a wrench so
that it does not turn together with the lock-
nut.
[ECB00521]
WARNING
EWB02090Operating with improperly serviced or adjust-
ed brakes could cause the brakes to malfunc-
tion, resulting in reduced braking
performance. This could increase the chance
of a collision or accident. After adjusting the
parking brake free play, block the rear of the
ATV off the ground and spin the rear wheels.
Check to make sure there is no brake drag. If
brake drag is noticed, perform the adjustment
again.EBU24742Brake light switches The brake light, which is activated by the brake
pedal and brake lever, should come on just before
braking takes effect.
1. Locknut
2. Parking brake free play adjusting nut
3. Rubber cover
(a)
(b)
1
2
3
Tightening torque:
Locknut (rear brake caliper):
16 Nm (1.6 m·kgf, 12 ft·lbf)
U18P64E0.book Page 32 Thursday, May 13, 2010 6:00 PM

8-33
8 The brake light switch for the brake pedal can be
adjusted as follows, but the front brake light switch
should be adjusted by a Yamaha dealer.
Turn the adjusting nut while holding the brake light
switch in place. To make the brake light come on
earlier, turn the adjusting nut in direction (a). To
make the brake light come on later, turn the adjust-
ing nut in direction (b).
EBU30151Adjusting the clutch lever free play The clutch lever free play must be checked and, if
necessary, adjusted at the intervals specified in the
periodic maintenance and lubrication chart.The clutch lever free play should measure 8.0–
13.0 mm (0.31–0.51 in) as shown. If the free play
is incorrect, adjust it as follows.
1. To increase the clutch lever free play, turn the
adjusting nut at the clutch lever in direction (a),
and to decrease it, turn the nut in direction (b).
If the specified free play cannot be obtained,
proceed with the following steps.
2. Fully turn the adjusting nut at the clutch lever
in direction (a) to loosen the clutch cable.
3. Slide the rubber cover back.
4. Loosen the clutch cable locknut, located to-
wards the center of the cable.1. Rear brake light switch
2. Rear brake light switch adjusting nut
1
2(a)(b)
1. Clutch lever free play
2. Clutch lever free play adjusting nut (clutch lever)
1
(a)
(b)
2
U18P64E0.book Page 33 Thursday, May 13, 2010 6:00 PM

8-34
85. To increase the clutch lever free play, turn the
adjusting nut located towards the center of the
cable in direction (a), and to decrease it, turn
the nut in direction (b).
6. Tighten the locknut.
7. Slide the rubber cover to its original position.
TIPIf the specified free play cannot be obtained as de-
scribed above or if the clutch does not operate cor-
rectly, have a Yamaha dealer check the internal
clutch mechanism.
EBU26864Drive chain slack The drive chain slack should be checked before
each ride and adjusted if necessary.
To check the drive chain slack
1. Place the ATV on a level surface.TIPWhen checking and adjusting the drive chain
slack, there should be no weight on the ATV and
all tires must be touching the ground.2. Move the ATV back and forth to locate the
tightest portion of the drive chain, and then
measure the drive chain slack as shown.
1. Locknut
2. Clutch lever free play adjusting nut (clutch cable)
3. Rubber cover
(a)
(b)
1
2
3
Drive chain slack:
25.0–35.0 mm (0.98–1.38 in)
U18P64E0.book Page 34 Thursday, May 13, 2010 6:00 PM