2014 YAMAHA YZ250F Owners Manual

ENGINE
3-19
c. Check the number on the originally installed
adjusting pad.
TIP
• The adjusting pad number “a” is indicated on
the top of the adjusting pad.
• For the number on the originally installed ad-
justing pad, convert the last digit of adjusting
pad number as per the below table.
d. Select an adjusting pad with a proper valve
clearance from the adjusting pad selection
table.
TIP
• There are 25 types of adjusting pads, ranging
from 1.20 mm (0.0472 in) to 2.40 mm (0.0945
in), in increments of 0.05 mm (0.0020 in).
• The field where the number on the originally
installed adjusting pad and the measured
valve clearance intersect shows the adjusting
pad number to replace.
Example:
Pad number = 148
Rounded value = 150
e. Install the new adjusting pads “4” and the
valve lifters “5”.
ECA@
NOTICE
Do not twist adjusting pads and valve lifters
forcibly during installation.
TIP
• Apply the engine oil on the valve lifters.
• Apply molybdenum disulfide oil to the valve
stem ends.
• Check that the valve lifters turn smoothly
when rotated with your finger.
• Make sure that valve lifters and adjusting
pads are installed in place.
• Make sure that adjusting pads are installed
with their numbers facing upward.
f. Install the camshafts (exhaust and intake).
Refer to “CAMSHAFT” on page 5-11.
g. Measure the valve clearance again.
h. If the valve clearance is out of specification,
repeat adjusting the valve clearance until it
is within specification.
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Last digit of pad
numberRounded valve
0, 1 or 2 0
4, 5 or 6 5
8 or 9 10
4 5

ENGINE
3-20
INTAKE
EXHAUST
120 125 130 135 140 145 150 155 160 165 170175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.02
0.06 0.00 0.01
120 125 130 135 140 145 150 155160165 170 175 180 185 190 195 200 205 210 215 220 225 230 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225
0.07
0.11120 125 130 135 140 145 150 155 160 165170 175 180 185 190 195 200 205 210 215 220 225 230 235
0.12
0.19
0.20
0.24125130135140145150155160165170175180 185 190 195 200 205 210 215 220 225 230 235240
0.250.29130135140145150155160165170175180185 190 195 200 205 210 215 220 225 230 235240
0.30 0.34 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.35 0.39 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.40 0.44 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.45 0.49 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.50 0.54 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.55 0.59 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.600.64 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.65 0.69 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.70 0.74 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.75 0.79 180 185 190 195 200 205 210 215 220 225 230 235240
0.80 0.84 185 190 195 200 205 210 215 220 225 230 235240
0.85 0.89 190 195 200 205 210 215 220 225 230 235240
0.90 0.94 195 200 205 210 215 220 225 230 235240
0.95 0.99 200 205 210 215 220 225 230 235240
1.001.04 205 210 215 220 225 230 235240
1.05 1.09 210 215 220 225 230 235240
1.10 1.14 215 220 225 230 235240
1.15 1.19 220 225 230 235240
1.20 1.24 225 230 235240
1.25 1.29 230 235240
1.30 1.34 235240
1.35 1.39 240
0.19
0.12
120 125 130 135 140 145 150 155 160 165 170175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.00
0.01 120 125 130 135 140 145150155 160 165 170 175 180 185 190 195 200 205 210 215 220
0.02
0.06120 125 130 135 140 145 150 155160 165 170 175 180 185 190 195 200 205 210 215 220 225
0.07
0.11120 125 130 135 140 145 150 155 160165 170 175 180 185 190 195 200 205 210 215 220 225 230
0.12 0.16120125130135140145150155160165170 175 180 185 190 195 200 205 210 215 220 225230235
0.17
0.24
0.25 0.29 125 130 135 140 145 150 155 160 165 170 175180 185 190 195 200 205 210 215 220 225230235240
0.30 0.34130135140145150155160165170175180185 190 195 200 205 210 215 220 225230235240
0.35 0.39 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.40 0.44 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.45 0.49 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.50 0.54 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.55 0.59 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.60 0.64 160 165 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.65 0.69 165 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.70 0.74 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.75 0.79 175 180 185 190 195 200 205 210 215 220 225230235240
0.80 0.84 180 185 190 195 200 205 210 215 220 225230235240
0.85 0.89 185 190 195 200 205 210 215 220 225230235240
0.90 0.94 190 195 200 205 210 215 220 225230235240
0.95 0.99 195 200 205 210 215 220 225230235240
1.00 1.04 200 205 210 215 220 225230235240
1.05 1.09 205 210 215 220 225230235240
1.10 1.14 210 215 220 225230235240
1.15 1.19 215 220 225230235240
1.20 1.24 220 225230235240
1.25 1.29 225230235240
1.30 1.34 230235240
1.35 1.39 235240
1.40 1.44 240
0.24
0.17

CHASSIS
3-21
EAS1SM1089
CHASSIS
EAS1SM1090BLEEDING THE BRAKE SYSTEMEWA13100
WARNING
Bleed the brake system whenever:
• The system is disassembled.
• A brake hose is loosened, disconnected,
or replaced.
• The brake fluid level is very low.
• Brake operation is faulty.
1. Remove:
• Brake master cylinder cap
• Reservoir diaphragm
• Reservoir float (front brake)
• Protector (rear brake)
TIP
• Be careful not to spill any brake fluid or allow
the reservoir to overflow.
• Make sure that there is enough brake fluid be-
fore applying the brake. Ignoring this precau-
tion could allow air to enter the brake system,
considerably lengthening the bleeding proce-
dure.
• If bleeding is difficult, it may be necessary to
let the brake fluid settle for a few hours. Re-
peat the bleeding procedure when the tiny
bubbles in the hose have disappeared.
2. Bleed the brake system.
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a. Fill the reservoir to the proper level with the
recommended brake fluid.
b. Install the reservoir diaphragm.
c. Connect the plastic hose “1” to the bleed
screw “2” securely, and place a container
under the end of the plastic hose.d. Slowly apply the brake several times.
e. Fully pull the brake lever or fully press down
the brake pedal and hold it in position.
f. Loosen the bleed screw.
TIP
Loosening the bleed screw will release the
pressure in the brake caliper and cause the
brake lever to contact the throttle grip or the
brake pedal to fully extend.
g. Tighten the bleed screw and then release
the brake lever or brake pedal.
h. Repeat steps (d) to (g) until all of the air bub-
bles have disappeared from the brake fluid
in the plastic hose.
TIP
During the procedure, keep adding brake fluid
to the reservoir.
ECA
NOTICE
Brake fluid may erode painted surfaces or
plastic parts. Always clean up spilled fluid
immediately.
i. Tighten the bleed screw.
j. Pour brake fluid to the reservoir up to the
specified level.
Refer to “CHECKING THE BRAKE FLUID
LEVEL” on page 3-26.
EWA13110
WARNING
After bleeding, check the brake operation.
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1 2
A
A. Front
B. Rear
Bleed screw
6 Nm (0.6 m·kgf, 4.3 ft·lbf)
2
1B
T R..

CHASSIS
3-22
EAS1SM1091CHECKING THE BRAKE HOSE
1. Check:
• Brake hose “1”
Cracks/damage/wear  Replace.
2. Check:
• Brake hose clamp
Loose Connection  Tighten the clamp bolt.
3. Stand the vehicle upright and apply the front
brake and the rear brake several times.
4. Check:
• Brake hoses
Brake fluid leaks  Replace the damaged
brake hose.
Refer to “FRONT BRAKE” on page 4-11.
Refer to “REAR BRAKE” on page 4-21.
EAS1SM1092ADJUSTING THE FRONT BRAKE
1. Check:
• Brake lever position “a”2. Remove:
• Brake lever cover
3. Adjust:
• Brake lever position
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Loosen the locknut “1”.
b. Turn the adjusting bolt “2” in direction “a” or
“b” until the specified brake lever position is
obtained.
c. Tighten the locknut.
EWA13050
WARNING
A soft or spongy feeling in the brake lever
can indicate the presence of air in the brake
system. Before running, bleed the brake
system. Air in the brake system will cause
braking performance to be reduced.
ECA13490
NOTICE
After adjusting the brake lever position,
make sure that there is no brake drag.
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4. Install:
• Brake lever cover
A. Front
B. Rear
Brake lever position
95 mm (3.74 in)
Extent of adjustment
86–105 mm (3.39–4.13 in)
1
1
Direction “a”
Brake lever position is increased.
Direction “b”
Brake lever position is decreased.
Locknut
5 Nm (0.5 m·kgf, 3.6 ft·lbf)
a
b
T R..

CHASSIS
3-23
EAS1SM1093ADJUSTING THE REAR BRAKE
1. Check:
• Brake pedal position “a”
(distance from the top of the rider footrest to
the top of the brake pedal)
Out of specification  Regulate.
2. Adjust:
• Brake pedal position
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a. Loosen the locknut “1”.
b. Turn the adjusting bolt “2” in direction “a” or
“b” until the specified brake pedal position is
obtained.
c. Tighten the locknut.
EWA1DX1001
WARNING
A soft or spongy feeling in the brake pedal
can indicate the presence of air in the brake
system. Before running, bleed the brake
system. Air in the brake system will cause
braking performance to be reduced.
ECA13510
NOTICE
After adjusting the brake pedal position,
make sure that there is no brake drag.
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EAS1SM1094CHECKING THE FRONT BRAKE PADS
1. Measure:
• Brake pad thickness “a”
Out of specification  Replace as a set.
TIP
The pads worn up to the indicator “b” grooves
mean that the brake pad thickness limit is
reached.
2. Replace:
• Brake pads
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the pad pin plug “1”. Brake pedal position
0.0 mm (0.00 in)
Direction “a”
Brake pedal is raised.
Direction “b”
Brake pedal is lowered.
Locknut
6 Nm (0.6 m·kgf, 4.3 ft·lbf)1 2
a
b
T R..
Brake pad lining thickness (inner)
4.4 mm (0.17 in)
Limit
1.0 mm (0.04 in)
Brake pad lining thickness (outer)
4.4 mm (0.17 in)
Limit
1.0 mm (0.04 in)
a
b
a
1

CHASSIS
3-24
b. Loosen the pad pin “2”.
c. Remove the brake caliper “3” from the front
fork.
d. Remove the pad pin and brake pads “4”.
e. Connect the plastic hose “5” to the bleed
screw “6” and place a container under the
end of the plastic hose.
f. Loosen the bleed screw and push the brake
caliper piston in.
EWA@
WARNING
Do not reuse the drained brake fluid.
g. Tighten the bleed screw.
h. Install the brake pads “7” and the pad pin.
TIP
• Install the brake pads with their projections “a”
into the brake caliper recesses “b”.
• Temporarily tighten the pad pin at this point.i. Install the brake caliper “8” and tighten the
pad pin “9”.
j. Install the pad pin plug “10”.
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3. Check:
• Brake fluid level
Refer to “CHECKING THE BRAKE FLUID
LEVEL” on page 3-26.
4. Check:
• Brake lever operation
A softy or spongy feeling  Bleed the brake
system.
Refer to “BLEEDING THE BRAKE SYS-
TEM” on page 3-21. Bleed screw
6 Nm (0.6 m·kgf, 4.3 ft·lbf)
3
2
4
6
5
T R..
Bolt (brake caliper)
28 Nm (2.8 m·kgf, 20 ft·lbf)
Pad pin
17 Nm (1.7 m·kgf, 12 ft·lbf)
Pad pin plug
2.5 Nm (0.25 m·kgf, 1.8 ft·lbf)
7
a b
T R..
8
9
T R..
10

CHASSIS
3-25
EAS1SM1095CHECKING THE REAR BRAKE PADS
1. Measure:
• Brake pad thickness “a”
Out of specification  Replace as a set.
TIP
The pads worn up to the indicator “b” grooves
mean that the brake pad thickness limit is
reached.
2. Replace:
• Brake pads
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the protector “1” and the pad pin
plug “2”.
b. Loosen the pad pin “3”.
c. Remove the rear wheel “4” and the brake
caliper “5”.
Refer to “REAR WHEEL” on page 4-7.d. Remove the pad pin “6” and the brake pads
“7”.
e. Connect the plastic hose “8” to the bleed
screw “9” and place a container under the
end of the plastic hose.
f. Loosen the bleed screw and push the brake
caliper piston in.
EWA@
WARNING
Do not reuse the drained brake fluid.
g. Tighten the bleed screw.
h. Install the brake pad “10” and the pad pin
“11”.
TIP
• Install the brake pads with their projections “a”
into the brake caliper recesses “b”.
• Temporarily tighten the pad pin at this point. Brake pad lining thickness (inner)
6.4 mm (0.25 in)
Limit
1.0 mm (0.04 in)
Brake pad lining thickness (outer)
6.4 mm (0.25 in)
Limit
1.0 mm (0.04 in)
ba
a
1 2
Bleed screw
6 Nm (0.6 m·kgf, 4.3 ft·lbf)
34
5
7 6
9
8
T R..

CHASSIS
3-26
i. Install the brake caliper “12” and the rear
wheel “13”.
Refer to “REAR WHEEL” on page 4-7.
j. Tighten the pad pin “14”.
k. Install the pad pin plug “15” and the protector
“16”.
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3. Check:
• Brake fluid level
Refer to “CHECKING THE BRAKE FLUID
LEVEL” on page 3-26.4. Check:
• Brake pedal operation
A softy or spongy feeling  Bleed the brake
system.
Refer to “BLEEDING THE BRAKE SYS-
TEM” on page 3-21.
EAS1SM1096CHECKING THE REAR BRAKE PAD INSU-
LATOR
1. Remove:
• Brake pads
Refer to “REAR BRAKE” on page 4-21.
2. Check:
• Rear brake pad insulator “1”
Damage  Replace.
EAS1SM1097CHECKING THE BRAKE FLUID LEVEL
1. Stand the vehicle upright on a level surface.
TIP
In order to ensure a correct reading of the brake
fluid level, make sure that the top of the brake
fluid reservoir is horizontal.
2. Check:
• Brake fluid level
The minimum level mark “a” or below 
Add. Pad pin
17 Nm (1.7 m·kgf, 12 ft·lbf)
Pad pin plug
2.5 Nm (0.25 m·kgf, 1.8 ft·lbf)
Bolt (protector)
7 Nm (0.7 m·kgf, 5.1 ft·lbf)
10 11
a
b
T R..
13
14
12
T R..
15
16Recommended brake fluid
DOT 4
A. Front brake
B. Rear brake