2017 YAMAHA WR 250F engine

ENGINE
3-21
TIP
• Place a cloth in the timing chain space to pre-
vent adjusting pads from falling into the crank-
case.
• Identity each valve lifter and adjusting pad po-
sition very carefully so that they can be rein-
stalled in their original place.
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 6-12. Valve lapper
90890-04101
Valve lapping tool
YM-A8998
1
32
Last digit of pad
numberRounded valve
0, 1 or 2 0
4, 5 or 6 5
8 or 9 10
4 5

ENGINE
3-22
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.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲

ENGINE
3-23
INTAKE
Example:
Valve clearance (cold) 0.12–0.19 mm
(0.0047–0.0075 in)
Installed is 175
Measured clearance 0.27 mm (0.0106 in)
Replace 175 pad with 185 pad
Pad No.175 = 1.75 mm (0.0689 in)
Pad No.185 = 1.85 mm (0.0728 in)
0.12 0.19
0.250.29 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.30
0.34 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.35
0.39 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.40
0.44 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.45
0.49 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.50
0.54 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.55
0.59 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.60
0.64 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.65
0.69 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.70
0.74 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.75
0.79 180 185 190 195 200 205 210 215 220 225 230 235 240
0.80
0.84 185 190 195 200 205 210 215 220 225 230 235 240
0.85
0.89 190 195 200 205 210 215 220 225 230 235 240
0.90
0.94 195 200 205 210 215 220 225 230 235 240
0.95
0.99 200 205 210 215 220 225 230 235 240
1.00
1.04 205 210 215 220 225 230 235 240
1.05
1.09 210 215 220 225 230 235 240
1.10
1.14 215 220 225 230 235 240
1.15
1.19 220 225 230 235 240
1.20
1.24 225 230 235 240
1.25
1.29 230 235 240
1.30
1.34 235 240
1.35
1.39 240
120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.02 0.06
120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 0.00
0.01120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225
0.07 0.11 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235
0.20 0.24 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
A. Measured clearance
B. Installed pad number
C. Standard clearance

ENGINE
3-24
EXHAUST
Example:
Valve clearance (cold) 0.17–0.24 mm
(0.0067–0.0094 in)
Installed is 175
Measured clearance 0.32 mm (0.0126 in)
Replace 175 pad with 185 pad
Pad No.175 = 1.75 mm (0.0689 in)
Pad No.185 = 1.85 mm (0.0728 in)
EAS2GBB100CLEANING THE SPARK ARRESTER
Refer to “CLEANING THE SPARK ARREST-
ER” on page 6-7.
0.17 0.24
0.25
0.29 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.30
0.34 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.35
0.39 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.40
0.44 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.45
0.49 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.50
0.54 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.55
0.59 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.60
0.64 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.65
0.69 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.70
0.74 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.75
0.79 175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.80
0.84 180 185 190 195 200 205 210 215 220 225 230 235 240
0.85
0.89 185 190 195 200 205 210 215 220 225 230 235 240
0.90
0.94 190 195 200 205 210 215 220 225 230 235 240
0.95
0.99 195 200 205 210 215 220 225 230 235 240
1.00
1.04 200 205 210 215 220 225 230 235 240
1.05
1.09 205 210 215 220 225 230 235 240
1.10
1.14 210 215 220 225 230 235 240
1.15
1.19 215 220 225 230 235 240
1.20
1.24 220 225 230 235 240
1.25
1.29 225 230 235 240
1.30
1.34 230 235240
1.35
1.39 235 240
1.40
1.44 240 0.00
0.01 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220
0.02
0.06 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225
0.07
0.11 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230
0.12
0.16 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235
120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
A. Measured clearance
B. Installed pad number
C. Standard clearance

CHASSIS
3-31
EWA
WARNING
• Use only the designated brake fluid. Other
brake fluids may cause the rubber seals to
deteriorate, causing leakage and poor
brake performance.
• Refill with the same type of brake fluid that
is already in the system. Mixing brake flu-
ids may result in a harmful chemical reac-
tion, leading to poor brake performance.
• When refilling, be careful that water does
not enter the brake fluid reservoir. Water
will significantly lower the boiling point of
the brake fluid and could cause vapor
lock.
ECA
NOTICE
Brake fluid may damage painted surfaces
and plastic parts. Therefore, always clean
up any spilt brake fluid immediately.
EAS2GBB110ADJUSTING THE DRIVE CHAIN SLACKECA
NOTICE
A drive chain that is too tight will overload
the engine and other vital parts, and one
that is too loose can skip and damage the
swingarm or cause an accident. Therefore,
keep the drive chain slack within the speci-
fied limits.
1. Use a suitable stand to raise the rear wheel
off the ground.
EWA
WARNING
Securely support the vehicle so that there is
no danger of it falling over.
2. Shift the transmission into the neutral posi-
tion.
3. Pull the drive chain up above the drive chain
guide installation bolt with a force of about
50 N (5.0 kgf, 36 lbf).
4. Check:
• Drive chain slack “a”
Out of specification  Regulate.
TIP
Measure drive chain slack between the drive
chain guide and the bottom of the chain as
shown.5. Adjust:
• Drive chain slack
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Loosen the wheel axle nut “1”.
b. Loosen both locknuts “2”.
c. Turn the adjusting bolt “3” in direction “a” or
“b” until the specified drive chain slack is ob-
tained.
TIP
• To maintain the proper wheel alignment, ad-
just both sides evenly.
• Push the rear wheel forward to make sure that
there is no clearance between the swingarm
end plates and the ends of the swingarm.
d. Tighten the wheel axle nut.
e. Tighten the locknut.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
Drive chain slack (on a suitable
stand)
50.0–60.0 mm (1.97–2.36 in)
Direction “a”
The drive chain slack decreases.
Direction “b”
The drive chain slack increases.
Wheel axle nut
125 Nm (12.5 m·kgf, 90 ft·lbf)
Locknut
21 Nm (2.1 m·kgf, 15 ft·lbf)
a
1
32
a
b
T R..
T R..

CHASSIS
3-38
c. Turn the front fork to the right and left a few
times, and make sure that the steering ro-
tates smoothly. If it does not turn smoothly,
remove the lower bracket and check the up-
per and lower bearings.
Refer to “STEERING HEAD” on page 5-53.
d. Loosen the ring nut fully turn and then tight-
en it to specification with a steering nut
wrench.
EWA
WARNING
Do not overtighten the lower ring nut.
e. Check the steering head for looseness or
binding by turning the front fork all the way in
both directions. If any binding is felt, remove
the lower bracket and check the upper and
lower bearings.
Refer to “STEERING HEAD” on page 5-53.
f. Install the washer “1”.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
5. Install:
• Upper bracket
Refer to “STEERING HEAD” on page 5-53.
• Handlebar
Refer to “HANDLEBAR” on page 5-33.
EAS2GBB124CHECKING AND LUBRICATING THE CA-
BLES
The following procedure applies to all of the in-
ner and outer cables.
EWA
WARNING
Damaged outer cable may cause the cable
to corrode and interfere with its movement.
Replace damaged outer cable and inner ca-
bles as soon as possible.1. Check:
• Outer cable
Damage  Replace.
2. Check:
• Cable operation
Rough movement  Lubricate.
TIP
Hold the cable end upright and pour a few
drops of lubricant into the cable sheath or use
a suitable lubricating device.
EAS2GBB125LUBRICATING THE LEVERS
1. Lubricate the pivoting points and metal-to-
metal moving parts of the following parts.
•Brake lever
• Clutch lever
EAS2GBB126LUBRICATING THE PEDAL
1. Lubricate the pivoting point and metal-to-
metal moving parts of the pedal.
EAS2GBB127LUBRICATING THE DRIVE CHAIN
The drive chain consists of many interacting
parts. If the drive chain is not maintained prop-
erly, it will wear out quickly. Therefore, the drive
chain should be serviced, especially when the
vehicle is used in dusty areas.
This vehicle has a drive chain with small rubber
O-rings between each side plate. Steam clean-
ing, high-pressure washing, certain solvents,
and the use of a coarse brush can damage
these O-rings. Therefore, use only kerosene to
clean the drive chain. Wipe the drive chain dry
and thoroughly lubricate it with engine oil or
chain lubricant that is suitable for O-ring chains.
Do not use any other lubricants on the drive
chain since they may contain solvents that
could damage the O-rings. Ring nut (initial tightening torque)
38 Nm (3.8 m·kgf, 27 ft·lbf)
Ring nut (final tightening torque)
7 Nm (0.7 m·kgf, 5.1 ft·lbf)
T R..
T R..
1
Recommended lubricant
Engine oil or a suitable cable lu-
bricant
Recommended lubricant
Silicone grease
Recommended lubricant
Lithium-soap-based grease
Recommended lubricant
Lithium-soap-based grease

ELECTRICAL SYSTEM
3-41
3. Adjust:
• Engine idling speed
Refer to “ADJUSTING THE ENGINE
IDLING SPEED” on page 3-18.
4. Check:
• Ignition timing
Check whether the alignment mark “a” on
the left crankcase cover is within the firing
range “b” on the rotor.
Incorrect firing range  Check rotor and
Crankshaft position sensor.
5. Install:
• Timing mark accessing screw
EAS2GBB133CHECKING AND CHARGING THE BATTERY
Refer to “CHECKING AND CHARGING THE
BATTERY” on page 9-69.
EAS2GBB134REPLACING THE HEADLIGHT BULBEWA
WARNING
Since the headlight bulb gets extremely hot,
keep flammable products and your hands
away from the bulb until it has cooled down.
1. Remove:
• Headlight unit bolt “1”
TIP
After you have removed the headlight unit
bolts, lift and remove the headlight unit.
2. Remove:
• Headlight coupler “1”
• Bulb cover “2”
3. Remove:
• Headlight bulb “1” Timing light
90890-03141
Timing light
YU-03141
Digital tachometer
90890-06760
Digital tachometer
YU-39951-B
Timing mark accessing screw
6 Nm (0.6 m·kgf, 4.3 ft·lbf)
2
1
3
ba
T R..
11
1
2
1

CHASSIS
4-3
TIP
Generally a stiff spring gives a stiff riding feel-
ing. Rebound damping tends to become weak-
er, resulting in lack of a sense of contact with
the road surface or in a vibrating handlebar.
EAS2GBB143FRONT FORK SETTING PARTS
• Front fork spring “1”
TIP
The I.D. mark (slits) “a” is proved on the end of
the spring.
EAS2GBB144REAR SUSPENSION SETTING
The rear shock absorber setting should be
made depending on the rider’s feeling of an ac-
tual run and the circuit conditions.
The rear suspension setting includes the fol-
lowing two factors:
1. Setting of spring preload
• Change the set length of the spring.
• Change the spring.
2. Setting of damping force
• Change the rebound damping force.
• Change the compression damping force.
EAS2GBB145CHOOSING SET LENGTH
1. Place a stand or a block under the engine to
put the rear wheel above the floor, and mea-
sure the length “a” between the rear wheel
axle center and the rear fender holding bolt.
2. Remove the stand or block from the engine
and, with a rider astride the seat, measure
the sunken length “b” between the rear
wheel axle center and the rear fender hold-
ing bolt.
3. Loosen the locknut “1” and make adjustment
by turning the adjuster “2” to achieve the
standard figure from the subtraction of the
length “b” from the length “a”. TypeSpring
rate N/
mmPart numberI.D.
Mark
(slits)
SOFT4.1 2GB-23141-A0 |||
4.2 2GB-23141-B0 ||||
4.3 2GB-23141-C0 |||||
STD 4.42GB-23141-30 —
2GB-23141-D0 |-|
STIFF4.5 2GB-23141-E0 |-||
4.6 33D-23141-30 |-|||
a
1
Standard figure
90–100 mm (3.5–3.9 in)