lock YAMAHA YZ250F 2014 Service Manual

CAMSHAFT
5-13
EAS1SM1208REMOVING THE CAMSHAFT
1. Remove:
• Timing mark accessing screw “1”
• Crankshaft end accessing screw “2”
2. Align:
• Alignment mark
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
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.
TIP
Align the alignment mark “c” on the exhaust
camshaft sprocket and the alignment mark “d”
on the intake camshaft sprocket with the edge
of the cylinder head.
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3. Remove:
• Timing chain tensioner cap bolt “1”
• Timing chain tensioner “2”
•Gaskets4. Remove:
• Bolt (camshaft cap) “1”
• Camshaft cap “2”
• Clip “3”
TIP
• Remove the bolts (camshaft cap) in a criss-
cross pattern, working from the outside in.
• In order to prevent the clip from falling into the
crankcase, remove the camshaft cap.
ECA33DD027
NOTICE
The bolts (camshaft cap) must be removed
evenly to prevent damage to the cylinder
head, camshafts or camshaft caps.
5. Remove:
• Exhaust camshaft “1”
• Intake camshaft “2”
TIP
Attach a wire “3” to the timing chain to prevent
it from falling into the crankcase.
1
2
b
a
dc
1 2
1
2
3

CAMSHAFT
5-15
c. Install the dowel pins and the camshaft
caps.
TIP
• Tighten the camshaft cap bolts in a crisscross
pattern from innermost to outer caps.
• Do not turn the camshaft when measuring the
camshaft journal-to-camshaft cap clearance.
d. Remove the camshaft caps and then mea-
sure the width of the Plastigauge® “1”.
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5. Measure:
• Camshaft journal diameter “a”
Out of specification  Replace the cam-
shaft.
Within specification  Replace the cylinder
head and the camshaft caps as a set.
EAS1SM1210CHECKING THE TIMING CHAIN AND CAM-
SHAFT SPROCKET
1. Check:
• Timing chain “1”
Damage/stiffness  Replace the timing
chain and camshaft and camshaft sprocket
as a set.2. Check:
• Camshaft sprocket
More than 1/4 tooth wear “a”  Replace the
camshaft sprocket and the timing chain as a
set.
EAS1SM1211CHECKING THE TIMING CHAIN TENSION-
ERS
1. Check:
• Timing chain tensioner
Crack/damage  Replace.
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a. While pressing the tensioner rod lightly with
your fingers, use a thin screwdriver “1” to
wind the tensioner rod up fully clockwise.
b. When releasing the screwdriver by pressing
lightly with your fingers, make sure that the
tensioner rod will come out smoothly.
c. If not, replace the tensioner assembly.
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Camshaft cap bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Camshaft journal diameter
21.959–21.972 mm (0.8645–
0.8650 in)
T R..
1
a. 1/4 tooth
b. Correct
1. Timing chain roller
2. Camshaft sprocket
a
b1
2

CAMSHAFT
5-16
EAS1SM1212CHECKING THE DECOMPRESSION SYS-
TEM
1. Check:
• Decompression system
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Check that the decompressor cam “1”
moves smoothly.
b. Check that the decompressor lever pin “2”
projects from the camshaft.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲EAS1SM1213INSTALLING THE CAMSHAFTS
1. Install:
• Exhaust camshaft “1”
• Intake camshaft “2”
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a. Turn the crankshaft counterclockwise with a
wrench.
TIP
• Apply molybdenum disulfide oil to the cam-
shafts.
• Apply the engine oil on the decompression
system.
b. Align the top dead center (TDC) mark “a” on
the rotor with the alignment mark “b” on the
crankcase cover.c. Fit the timing chain “3” onto both camshaft
sprockets and install the camshafts on the
cylinder head.
TIP
Make sure that the alignment mark “c” on the
exhaust camshaft sprocket and the alignment
mark “d” on the intake camshaft sprocket are
aligned with the edge of the cylinder head.
ECA33DD029
NOTICE
Do not turn the crankshaft during the cam-
shaft installation. Damage or improper
valve timing will result.
d. Install the clips, the camshaft caps and the
bolts (camshaft cap).
TIP
• Before installing the clips, cover the cylinder
head with a clean cloth to prevent the clips
from coming off into the cylinder head cavity.
• Tighten the bolts to the specified torque in two
or three steps in the proper tightening se-
quence as shown.
ECA33DD030
NOTICE
The bolts (camshaft cap) must be tightened
evenly, or damage to the cylinder head,
camshaft caps, and camshaft will result.
1
2
Bolt (camshaft cap)
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
b
a
dc
3
T R..

CAMSHAFT
5-17
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2. Install:
• Timing chain tensioner
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a. While pressing the tensioner rod lightly with
your fingers, use a thin screwdriver to wind
the tensioner rod up fully clockwise.
b. With the tensioner rod fully wound and the
chain tensioner UP mark “a” facing upward,
install the gasket “1”, the timing chain ten-
sioner “2”, and the gasket “3”, and tighten
the bolt “4”.
c. Release the screwdriver, check that the ten-
sioner rod comes out smoothly, and tighten
the gasket “5” and the cap bolt “6”.
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3. Turn:
• Crankshaft
Counterclockwise several turns.
4. Check:
• Top dead center (TDC) mark on the rotor
Align with the crankcase alignment mark.
• Camshaft match marks
Align with the cylinder head surface.
Out of alignment  Adjust.
5. Install:
• Timing chain guide (top side) “1”
• Cylinder head cover gasket “2”
• Cylinder head cover “3”
• Bolt (cylinder head cover) “4”
TIP
Before installation, apply the sealant to the cyl-
inder head cover gasket.
6. Install:
• Cylinder head breather hose
• Spark plug Bolt (timing chain tensioner)
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Tensioner cap bolt
6 Nm (0.6 m·kgf, 4.3 ft·lbf)
3
4
8
7
15
26
T R..
T R..
Bolt (cylinder head cover)
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Three Bond No.1215®
90890-85505
Spark plug
13 Nm (1.3m·kgf, 9.4 ft·lbf)
6 5
T R..
4
4
3
21
T R..

CLUTCH
5-38
EAS1SM1233REMOVING THE CLUTCH
1. Remove:
• Clutch boss nut “1”
• Lock washer “2”
• Clutch boss “3”
TIP
• Straighten the lock washer tab.
• While holding the clutch boss with the clutch
holder “4”, loosen the clutch boss nut.
EAS1SM1234CHECKING THE FRICTION PLATES
1. Check:
• Friction plate
Damage/wear  Replace the friction plates
as a set.
2. Measure:
• Friction plate thickness
Out of specification  Replace the friction
plates as a set.
TIP
Measure it at four points on the friction plate.
EAS1SM1235
CHECKING THE CLUTCH PLATES
1. Check:
• Clutch plate
Damage  Replace the clutch plates as a
set.
2. Measure:
• Clutch plate warpage
(with a surface plate and thickness gauge
“1”)
Out of specification  Replace the clutch
plates as a set.
EAS1SM1236CHECKING THE CLUTCH SPRINGS
1. Check:
• Clutch spring
Damage  Replace the clutch springs as a
set.
2. Measure:
• Clutch spring free length
Out of specification  Replace the clutch
springs as a set.
EAS1SM1237
Clutch holder
90890-04086
YM-91042
Friction plate thickness
2.90–3.10 mm (0.114–0.122 in)
Wear limit
2.80 mm (0.110 in)
34
12
Warpage limit
0.10 mm (0.0039 in)
Clutch spring free length
45.00 mm (1.77 in)
Limit
44.00 mm (1.73 in)

CLUTCH
5-41
INSTALLING THE CLUTCH
1. Install:
• Push lever shaft “1”
TIP
• Apply the lithium soap base grease on the oil
seal lip.
• Before installation, apply the engine oil to the
push lever shaft sliding surface.
2. Install:
• Primary driven gear “1”
• Thrust washer “2”
• Clutch boss “3”
TIP
Apply the engine oil on the primary driven gear
inner circumference.
3. Install:
• Lock washer “1”
• Clutch boss nut “2”
ECA1DX1020
NOTICE
Make sure to tighten to specification; other-
wise, it may damage the other part that is
fastened together.
TIP
Use the clutch holding tool “3” to hold the clutch
boss.4. Bend the lock washer “1” tab.
5. Install:
• Friction plate “1”
• Clutch plate “2”
• Cushion spring “3”
TIP
• Install the clutch plates and friction plates al-
ternately on the clutch boss, starting with a
friction plate and ending with a friction plate.
• Install the cushion spring “3” in the position as
shown.
• Apply the engine oil on the friction plates and
clutch plates.
Clutch boss nut
75 Nm (7.5 m·kgf, 54 ft·lbf)
1
New
T R..
Clutch holder
90890-04086
YM-91042
3
21
1
1
1
2 2
2
1
2
3

KICKSTATER
5-46
3. Install:
• Spring guide “1”
TIP
Slide the spring guide into the kick shaft, make
sure the groove “a” in the spring guide fits on
the stopper of the torsion spring.
4. Install:
• Kick shaft assembly “1”
TIP
• Before installation, apply molybdenum disul-
fide grease to the contacting surfaces of the
kick shaft ratchet wheel guide “2” and the kick
shaft stopper “a”.
• Apply the engine oil on the kick shaft.
• Slide the kick shaft assembly into the crank-
case and make sure the kick shaft stopper “a”
fits into the kick shaft ratchet wheel guide.5. Install:
• Torsion spring “1”
TIP
Turn the torsion spring clockwise and hook into
the proper hole “a” in the crankcase.
EAS1SM1253INSTALLING THE KICK IDLE GEAR
1. Install:
• Kick idle gear “1”
• Washer “2”
• Circlip “3”
TIP
• Apply the engine oil on the kick idle gear inner
circumference.
• Install the kick idle gear with its depressed
side “a” toward you.
1 2a b
New

SHIFT SHAFT
5-49
EAS1SM1255REMOVING THE SHIFT GUIDE AND SHIFT
LEVER ASSEMBLY
1. Remove:
• Bolt (shift guide)
• Shift guide “1”
• Shift lever assembly “2”
TIP
Make sure that the shift lever assembly is re-
moved together with the shift guide.
EAS1SM1256REMOVING THE SEGMENT
1. Remove:
• Bolt (segment) “1”
• Segment “2”
TIP
Turn the segment counterclockwise until it
stops and loosen the bolt.
ECA1DX1021
NOTICE
If the segment gets an impact, it may be
damaged. Take care not to give an impact to
it when removing the bolt.
EAS1SM1257
CHECKING THE SHIFT SHAFT
1. Check:
• Shift shaft “1”
Bends/damage/wear  Replace.
• Shift shaft spring “2”
Damage/wear  Replace.
EAS1SM1258CHECKING THE SHIFT GUIDE AND SHIFT
LEVER ASSEMBLY
1. Check:
• Shift guide “1”
• Shift lever “2”
•Pawl “3”
• Pawl pin “4”
• Spring “5”
Wear/damage  Replace.
EAS1SM1259CHECKING THE STOPPER LEVER
1. Check:
• Stopper lever “1”
Wear/damage  Replace.
• Torsion spring “2”
Broken  Replace.
EAS1SM1260
1
2
1
2
3
4
5

FUEL INJECTION SYSTEM
8-14
Fault code 12
SymptomCrankshaft position sensor: no normal signals are received
from the crankshaft position sensor.
Fail-safe systemUnable to start engine
Unable to drive vehicle
Diagnostic code No.—
Diagnostic tool display—
Procedure—
Or-
derProbable cause of malfunc-
tion and checkMaintenance job Reinstatement method
1 Connection of crankshaft po-
sition sensor coupler.
Check the locking condition
of the coupler.
Disconnect the coupler, and
check the pins (for bent or
broken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler secure-
ly, or repair/replace the wire
harness.Crank the engine.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
2 Connection of wire harness
ECU coupler.
Check the locking condition
of the coupler.
Disconnect the coupler, and
check the pins (for bent or
broken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler secure-
ly, or repair/replace the wire
harness.Crank the engine.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
3 Wire harness continuity. Open or short circuit  Re-
place the wire harness.
Between the crankshaft posi-
tion sensor coupler and ECU
coupler.
gray–gray
black/blue–black/blueCrank the engine.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
4 Mounted condition of crank-
shaft position sensor.
Check for looseness or
pinching.
Check the gap between the
crankshaft position sensor
and the pickup rotor.Improperly mounted sensor
 Remount or replace the
sensor. “AC MAGNETO” on
page 5-58.Crank the engine.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
5 Defective crankshaft position
sensor.Check the crankshaft position
sensor.
“CHECKING THE CRANK-
SHAFT POSITION SEN-
SOR” on page 8-42.Crank the engine.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
6 Faulty ECU Replace the ECU.

FUEL INJECTION SYSTEM
8-15
TIP
If fault code Nos. 13 and 14 are both displayed, perform checkup and repair jobs for fault code No.
13 first.
Fault code 13
Symptom Intake air pressure sensor: open or short circuit detected.
Fail-safe systemAble to start engine
Able to drive vehicle
Diagnostic code No.03
Diagnostic tool displayDisplays the intake air pressure.
ProcedureThe atmospheric pressure is displayed on the Yamaha diagnostic
tool.
Or-
derProbable cause of malfunc-
tion and checkMaintenance job Reinstatement method
1 Connection of intake air pres-
sure sensor coupler.
Check the locking condition
of the coupler.
Disconnect the coupler, and
check the pins (for bent or
broken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler secure-
ly, or repair/replace the wire
harness.Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
2 Connection of wire harness
ECU coupler.
Check the locking condition
of the coupler.
Disconnect the coupler, and
check the pins (for bent or
broken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler secure-
ly, or repair/replace the wire
harness.Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
3 Connection of sub wire har-
ness coupler.
Check the locking condition
of the coupler.
Disconnect the coupler, and
check the pins (for bent or
broken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler secure-
ly, or repair/replace the sub-
wire harness.Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
4 Wire harness continuity. Open or short circuit  Re-
place the wire harness.
Between intake air pressure
sensor coupler and ECU cou-
pler.
pink/black–pink/black
blue–blue
black/blue–black/blueTurn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
5 Mounted condition of intake
air pressure sensor.
Check for looseness or
pinching.
Check the mounted position
for correctness.Improperly mounted sensor
 Remount or replace the
sensor.Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.