engine YAMAHA WR 250F 2015 Workshop Manual

ENGINE
3-12
EAS2GB2089CHECKING THE COOLANT CIRCULATORY
SYSTEM FOR LEAKS
1. Check:
• Coolant level
2. Install:
• Radiator cap tester “1”
• Adapter “2”
3. Activate the tester to apply the test pressure.
ECA
NOTICE
• Do not apply such a high pressure as ex-
ceeds the test pressure.
• Make sure that a checkup after the cylin-
der head gasket is replaced is made after 3
minutes of warm-up.
• Make sure that coolant is filled up to the
upper level beforehand.
4. Check:
• Pressure value
No stay for 5 to 10 seconds at the test pres-
sure value  Correct.
• Radiator
• Radiator hose connections
Coolant leaks  Correct or replace.
• Radiator hoses
Bulges  Replace
EWA
WARNING
When the radiator cap tester is removed,
coolant will spout; therefore, cover it with a
cloth beforehand.
EAS2GB2090ADJUSTING THE CLUTCH LEVER FREE
PLAY
1. Check:
• Clutch lever free play “a”
Out of specification  Regulate.
2. Adjust:
• Clutch lever free play
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Handlebar side
a. Turn the adjuster “1” in direction “a” or “b”
until the specified clutch lever free play is ob-
tained.
TIP
If the clutch lever free play cannot be obtained
on the handlebar side, use the adjuster on the
clutch cable side.
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Clutch cable side
a. Slide the clutch cable cover.
b. Loosen the locknut “1”. Radiator cap tester
90890-01325
Mityvac cooling system tester kit
YU-24460-A
Radiator cap tester adapter
90890-01352
Pressure tester adapter
YU-33984
Test pressure value
196 kPa (1.96 kg/cm
2, 27.9 psi)
Clutch lever free play
7.0–12.0 mm (0.28–0.47 in)
Direction “a”
Clutch lever free play is increased.
Direction “b”
Clutch lever free play is decreased.
a b
1

ENGINE
3-13
c. Turn the adjuster “2” in direction “a” or “b”
until the specified clutch lever free play is ob-
tained.
d. Tighten the locknut “1”.
e. Return the clutch cable cover to its original
position.
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EAS2GB2091ADJUSTING THE THROTTLE GRIP FREE
PLAY
TIP
Prior to adjusting throttle grip free play, the en-
gine idling speed should be adjusted.
1. Check:
• Throttle grip free play “a”
Out of specification  Regulate.2. Adjust:
• Throttle grip free play
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a. Loosen the locknut “1”.
b. Turn the adjuster “2” until the specified free
play is obtained.
c. Tighten the locknut.
EWA
WARNING
After adjusting the throttle grip free play,
turn the handlebar to the right and to the left
to ensure that this does not cause the en-
gine idling speed to change.
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EAS2GB2092LUBRICATING THE THROTTLE CABLE
1. Remove:
• Cover (throttle cable cap) “1”
• Cover (grip cap) “2”
• Throttle grip cap “3” Direction “a”
Clutch lever free play is increased.
Direction “b”
Clutch lever free play is decreased.
Locknut
4.0 Nm (0.40 m·kgf, 2.9 ft·lbf)
Throttle grip free play
3.0–5.0 mm (0.12–0.20 in)
T R..
1
2a
b
Direction “a”
Throttle grip free play is increased.
Direction “b”
Throttle grip free play is decreased.
1 2
b
a

ENGINE
3-14
2. Lubricate:
• Throttle cable end “a”
3. Install:
• Throttle grip cap
• Screw (throttle grip cap)
4. Install:
• Cover (grip cap)
• Cover (throttle cable cap)
EWA
WARNING
Check that the throttle grip moves smooth-
ly. If this does not move smoothly, correct
the installed positions.
EAS2GB2093CLEANING THE AIR FILTER ELEMENT
1. Remove:
• Fuel tank cap cover “1”
Refer to “FUEL TANK CAP” on page 1-23.
• Air filter case cover “2”
TIP
Loosen the quick fastener screw “3” and re-
move the air filter case cover.2. Remove:
• Air filter mounting bolt “1”
• Air filter element “2”
• Air filter guide “3” (from the air filter element)
3. Wash:
• Air filter element
EWA
WARNING
Do not use gasoline or organic (acid/alka-
line) volatile oil for washing.
TIP
After washing the element with air filter cleaner
or kerosene, squeeze and dry it completely.
ECA
NOTICE
Do not twist the element when squeezing
the element.
4. Check:
• Air filter element
Damage  Replace.
5. Foam-air-filter oil or equivalent oil to the ele-
ment
TIP
Squeeze out the excess oil. Element should be
wet but not dripping. Recommended lubricant
Lithium-soap-based grease
Screw (throttle grip cap)
3.8 Nm (0.38 m·kgf, 2.8 ft·lbf)
T R..
1
2
3
3
3
Oil application quantify
50 g
13
2

ENGINE
3-15
6. Install:
• Air filter guide “1” (to the air filter element)
• Air filter element “2”
• Air filter mounting bolt “3”
7. Install:
• Air filter case cover “1”
TIP
Align the air filter case cover groove “a” with the
air filter case edge “b”.
8. Install:
• Fuel tank cap cover
EAS2GB2094CHECKING THE THROTTLE BODY JOINT
1. Check:
• Throttle body joint
Refer to “CHECKING THE THROTTLE
BODY JOINT” on page 8-10.
EAS2GB2095CHECKING THE BREATHER HOSES
1. Check:
• Breather hose “1”
Crack/damage  Replace.
Loose connection  Connect properly.
ECA
NOTICE
Make sure the cylinder head breather hose
is routed correctly.
EAS2GB2096CHECKING THE EXHAUST SYSTEM
1. Remove:
• Exhaust pipe protector
2. Check:
• Exhaust pipe 1
• Exhaust pipe 2
• Silencer
Crack/damage  Replace.
Refer to “ENGINE REMOVAL” on page 6-1.
• Exhaust gas
Leaks  Replace the gasket.
Refer to “ENGINE REMOVAL” on page 6-1.
3. Check:
• Tightening torques Air filter mounting bolt
2.0 Nm (0.20 m·kgf, 1.4 ft·lbf)
T R..
31
2
a
b 1Exhaust pipe bolt 1 and nut “1”
20 Nm (2.0 m·kgf, 14 ft·lbf)
Exhaust pipe 1 and exhaust pipe
2 bolt “2”
12 Nm (1.2 m·kgf, 8.7 ft·lbf)
Exhaust pipe 2 and silencer bolt
“3”
12 Nm (1.2 m·kgf, 8.7 ft·lbf)
Silencer and silencer bracket bolt
“4”
30 Nm (3.0 m·kgf, 22 ft·lbf)
1
1
1
T R..
2
1

ENGINE
3-16
4. Install:
• Exhaust pipe protector
EAS2GB2097CHECKING THE FUEL LINE
1. Remove:
• Seat
• Side cover (left/right)
• Air scoop (left/right)
Refer to “GENERAL CHASSIS” on page 5-
1.
• Fuel tank
Refer to “FUEL TANK” on page 8-1.
2. Check:
• Fuel hose “1”
Crack/damage  Replace.
Loose connection  Connect properly.
3. Install:
• Fuel tank
Refer to “FUEL TANK” on page 8-1.
• Air scoop (left/right)
• Seat
• Side cover (left/right)
Refer to “GENERAL CHASSIS” on page 5-
1.
EAS2GB2098
CHECKING THE ENGINE OIL LEVEL
1. Stand the vehicle upright on a level surface.
2. Start the engine, warm this up for 3 minutes,
and then stop the engine and wait about 5
minute.
3. Check:
• Oil level
The engine oil level should be between the
minimum level mark “a” and maximum level
mark “b”.
Below the minimum level mark  Add the
recommended engine oil to the proper level.
ECA
NOTICE
• Since engine oil also lubricates the clutch,
the wrong oil types or additives could
cause clutch slippage. Therefore, do not
add any chemical additives.
• Do not allow foreign material to enter the
crankcase. Exhaust pipe protector screw
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
LOCTITE®
4
3
T R..
1
Recommended brand
YAMALUBE
Recommended engine oil type
SAE10W-30, SAE10W-40,
SAE10W-50, SAE15W-40,
SAE20W-40 or SAE20W-50
Recommended engine oil grade
API service SG type or higher,
JASO standard MA
a b

ENGINE
3-17
EAS2GB2099CHANGING THE ENGINE OIL
Stand the vehicle upright on a level surface.
1. Start the engine, warm this up for 3 minutes,
and then stop the engine and wait about 5
minutes.
2. Place an oil pan under the drain bolt.
3. Remove:
• Engine guard “1”
• Oil filler cap “2”
• Drain bolt (with gasket) “3”
4. If the oil filter element is also to be replaced,
perform the following procedure.
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a. Remove the oil filter element cover “1” and
oil filter element “2”.
b. Replace the O-ring “3”.
c. Install the new oil filter element and the oil fil-
ter element cover.
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5. To check the oil strainer, perform the follow-
ing procedure.
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a. Remove the oil strainer “1”.
b. Check the oil strainer.
Damage  Replace.
Clogging due to dirt  Wash with kerosene.
c. Replace the O-ring “2”.
d. Install the oil strainer.
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6. Install:
•Gasket
• Drain bolt
7. Pour the specified amount of engine oil into
the oil filler cap hole.
Oil filter element cover bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
12
3
1
3
2
New
T R..
Oil strainer bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Drain bolt
20 Nm (2.0 m·kgf, 14 ft·lbf)
Engine oil quantity
Without oil filter element replace-
ment
0.83 L (0.88 US qt, 0.73 Imp.qt)
With oil filter element replace-
ment
0.85 L (0.90 US qt, 0.75 Imp.qt)
Quantity (disassembled)
1.10 L (1.16 US qt, 0.97 Imp.qt)
1
2New
T R..
New
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ENGINE
3-18
8. Install:
• Oil filler cap
9. Check:
• Oil level
Refer to “CHECKING THE ENGINE OIL
LEVEL” on page 3-16.
10.Check:
• Engine oil pressure
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a. Slightly loosen the oil pressure check bolt
“1”.
EWA
WARNING
When the engine is started with the check
bolt removed, oil will spout; therefore, al-
ways loosen it before the checkup.
Start the engine and keep it idling until oil
starts to seep from the oil pressure check
bolt.
EWA
WARNING
Always keep the engine idling speed during
the checkup without increasing the engine
speed.
ECA
NOTICE
If no engine oil seeps out after one minute,
immediately turn the engine off so it will not
seize.
b. If no engine oil seeps out, check the engine
oil for leaks, and the engine oil passage and
the oil pump for damage.
c. Check the oil pressure again.
d. Tighten the oil pressure check bolt.
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EAS2GB2100
ADJUSTING THE ENGINE IDLING SPEED
TIP
• Because the air pressure is lower at high alti-
tudes, the air-fuel mixture will become richer.
If the idling speed is low, turn the starter knob/
idle screw a few clicks counterclockwise to in-
crease the speed before the adjustment.
• Before adjusting the engine idling speed,
make sure that the air filter element is not
clogged, the engine compression is proper,
and the throttle grip free play is proper.
• Adjust the engine idling speed with the starter
knob/idle screw pushed in completely.
1. Start the engine, and warm this up until the
oil has reached the specified temperature.
2. Attach the pocket tester with temperature
probe “1” to the oil drain bolt.
3. Install:
• Digital tachometer
TIP
Get the high tension cord “1” of the ignition coil
pinched in the detector “a” of the digital tachom-
eter.
Oil pressure check bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
1
T R..
Oil temperature
70.0–80.0 °C (158.00–176.00 °F)
Digital tachometer
90890-06760
Digital tachometer
YU-39951-B
1
1 1
a a

ENGINE
3-19
4. Measure:
• Engine idling speed
Out of specification  Regulate.
5. Adjust:
• Engine idling speed
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a. Turn the starter knob/idle screw “1” in the di-
rection of “a” or “b” to make an adjustment.
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EAS2GB2101ADJUSTING THE VALVE CLEARANCE
TIP
• This section is intended for those who have
basic knowledge and skill concerning the ser-
vicing of Yamaha motorcycles (e.g., Yamaha
dealers, service engineers, etc.). Those who
have little knowledge and skill concerning ser-
vicing are requested not to undertake inspec-
tion, adjustment, disassembly, or reassembly
only by reference to this manual. It may lead
to servicing trouble and mechanical damage.
• Make sure that the valve clearance is
checked or adjusted while the engine is cold
(at room temperature).
• While the valve clearance is checked or ad-
justed, make sure that the piston is positioned
in the top dead center (TDC).1. Remove:
• Seat
• Side cover (left/right)
• Air scoop (left/right)
Refer to “GENERAL CHASSIS” on page 5-
1.
• Fuel tank
Refer to “FUEL TANK” on page 8-1.
•ECU
2. Remove:
• Spark plug
• Cylinder head cover
Refer to “CAMSHAFT” on page 6-11.
3. Remove:
• Timing mark accessing screw “1”
• Crankshaft end accessing screw “2”
• O-ring
4. Check:
• Valve clearance
Out of specification  Regulate.
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a. Turn the crankshaft counterclockwise with a
wrench.
b. Align the top dead center (TDC) mark “a” on
the rotor with the alignment mark “b” on the
crankcase cover. Engine idling speed
1900–2100 r/min
Direction “a” Engine idling speed  De-
creases.
Direction “b” Engine idling speed  In-
creases.
1 b
a
Valve clearance (cold)
Intake
0.12–0.19 mm (0.0047–0.0075 in)
Exhaust
0.17–0.24 mm (0.0067–0.0094 in)
12
ab

ENGINE
3-20
TIP
Check that the alignment mark “c” on the cam-
shaft sprocket and the alignment mark “d” on
the intake camshaft sprocket are aligned with
the edge of the cylinder head.
c. Measure the valve clearance “e” using a
thickness gauge “1”.
TIP
Record the measured reading if the clearance
is incorrect.
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5. Adjust:
• Valve clearance
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a. Remove the camshaft (intake and exhaust).
Refer to “CAMSHAFT” on page 6-11.
b. Remove the valve lifter “2” and the adjusting
pad “3” with a valve lapper “1”.
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.
dc
ee
1
Valve lapper
90890-04101
Valve lapping tool
YM-A8998
1
32

ENGINE
3-21
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 6-11.
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