YAMAHA YFZ450R 2021 Owners Manual

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17. 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 areas. Each time the air filter element main-
tenance is performed, check the air inlet of the air
filter case for obstructions. Check the air filter
case rubber joint to the throttle body and the rub-
ber joint manifold fittings for an air-tight seal.
Tighten all fittings securely to avoid the possibility
of unfiltered air entering the engine. EBU30863Cleaning the spark arresterSelect a well-ventilated area free of combustible
materials and make sure the exhaust and muffler
are cool.
WARNING
EWB02342Always let the exhaust system cool prior to
touching exhaust components.
Do not start the engine with the spark arrester
removed. Sparks or exhaust particulate can
cause eye injury, burns, or start a fire.
1. Remove the tailpipe cover by removing the
bolts.
2. Remove the retainer by removing the bolts, and then remove the tailpipe and gasket from
the muffler.1. Tailpipe cover
2. Bolt2
1 2
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93. 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. Install the gasket, tailpipe, and retainer and
align the bolt holes.
5. Install the bolts and tighten them to the spec- ified torque.
6. Install the tailpipe cover and align the bolt holes.
7. Install the bolts and tighten them to the spec- ified torque.
1. Bolt
2. Retainer
3. Tailpipe
4. Gasket1
2
3
4
1
1. Tailpipe
2. Spark arresterTightening torque:Retainer bolt:10 N·m (1.0 kgf·m, 7.4 lb·ft)
1
2
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EBU29705Adjusting the throttle lever free playPeriodically check the throttle lever free play and
adjust if necessary.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.
EBU24062Valve clearanceThe 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 chart.EBU29602BrakesReplacement of brake components requires pro-
fessional knowledge. Brake service should be
performed by a Yamaha dealer.
Tightening torque:
Tailpipe cover bolt:8 N·m (0.8 kgf·m, 5.9 lb·ft)
1. Rubber cover
2. Throttle lever free play adjusting bolt
3. Locknut
4. Throttle lever free playThrottle lever free play: 2.0–4.0 mm (0.08–0.16 in)
32
4
(a)(b)
1
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WARNING
EWB02572Operating with improperly serviced or adjust-
ed brakes could lead to a loss in braking ability
and an accident. EBU24132Checking the front and rear brake padsThe front and rear brake pads must be checked
for wear at the intervals specified in the periodic
maintenance chart.EBU29561Front 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 dis-
appeared, have a Yamaha dealer replace the
brake pads as a set.
TIPThe wheels need to be removed to check the
brake pads. (See page 9-49.) EBU29832Rear 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 dis-
appeared, have a Yamaha dealer replace the
brake pads as a set.1. Wear indicator groove
1
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EBU29502Checking the brake fluid levelBefore riding, check that the brake fluid is above
the minimum level mark. Check the brake fluid lev-
el with the top of the reservoir level. Replenish the
brake fluid if necessary.Front brake
Rear brake1. Wear indicator groove
1
1. Minimum level mark
1. Minimum level mark
1
1
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TIPTo check the rear brake fluid level, remove the
seat. (See page 5-10.)
WARNING
EWB02721Improper 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 flu-
id and may result in vapor lock.
NOTICEECB01161Brake 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
brake pads for wear and the brake system for
leakage. If the brake fluid level goes down sud-
denly, have a Yamaha dealer check the cause be-
fore further riding.EBU24294Changing the brake fluidHave a Yamaha dealer change the brake fluid at
the intervals specified in the periodic maintenance
chart. In addition, have the oil seals of the master
Specified brake fluid:
DOT 4
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cylinders and calipers as well as the brake hoses
replaced at the intervals listed below or whenever
they are damaged or leaking.

Oil seals: Replace every two years.
 Brake hoses: Replace every four years.
EBU24396Checking the front brake lever free
playThere should be no free play at the brake lever
end. If there is free play, have a Yamaha dealer in-
spect the brake system.
EBU24616Checking the brake pedal heightPeriodically check the brake pedal height. If the
brake pedal is not positioned as specified, have a
Yamaha dealer adjust it.
1. No brake lever free play
1
1. Brake pedal heightBrake pedal height: 11.7 mm (0.46 in)
1
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EBU24717Adjusting the parking brake free playPeriodically check the cable length “A” and adjust
if necessary.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 at the brake ca-
ble.
4. Loosen the locknut.
5. Turn the parking brake free play adjusting nut in direction (a) to increase the cable length,
and in direction (b) to decrease it.
TIPIf the cable length cannot be adjusted to specifi-
cation, consult a Yamaha dealer. 6. Tighten the locknut on the brake cable.
7. Slide the rubber cover to its original position.
1. Adjusting bolt
2. Cable length “A”
3. LocknutCable length “A”:47–51 mm (1.85–2.01 in)
1
2
3
1. Locknut
2. Parking brake free play adjusting nut
3. Rubber cover
1
2
3
(b)
(a)
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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.
[ECB00522]
WARNING
EWB02091Operating 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.
EBU24744Brake light switchesThe brake light, which is activated by the brake
pedal and brake lever, should come on just before
braking takes effect.
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 rear brake light switch 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 adjusting nut in direction (b).
Tightening torque:
Locknut (rear brake caliper):16 N·m (1.6 kgf·m, 12 lb·ft)1. Rear brake light switch
2. Rear brake light switch adjusting nut
1
2(a) (b)
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EBU30155Adjusting the clutch lever free playPeriodically check the clutch lever free play and
adjust if necessary.1. To increase the clutch lever free play, turn the clutch lever free play 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 back the rubber cover at the clutch ca- ble.
4. Loosen the locknut.
5. To increase the clutch lever free play, turn the clutch lever free play adjusting nut located to-
wards 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.1. Clutch lever free play
2. Clutch lever free play adjusting nut (clutch lever)Clutch lever free play: 8.0–13.0 mm (0.31–0.51 in)
1
(a)
(b)
2
1. Locknut
2. Clutch lever free play adjusting nut (clutch cable)
3. Rubber cover
1
2
3
(b)
(a)
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