2001 YAMAHA YZ250F check oil

4 - 99
ENGTRANSMISSION, SHIFT CAM AND SHIFT FORK
5. Install:
lShift fork 1 (L) 1
lShift fork 2 (C) 2
lShift fork 3 (R) 3
lShift cam 4
To main axle and drive axle.
NOTE:
lApply the molybdenum disulfide oil on the
shift fork grooves.
lMesh the shift fork #1 (L) with the 4th wheel
gear 5 and #3 (R) with the 5th wheel gear
7 on the drive axle.
lMesh the shift fork #2 (C) with the 3rd pinion
gear 6 on the main axle.
6. Install:
lTransmission assembly 1
To left crankcase 2.
NOTE:
Apply the engine oil on the bearings and guide
bars.
7. Check:
lShifter operation
lTransmission operation
Unsmooth operation ® Repair.

5 - 35
CHASFRONT FORK
13. Check:
lInner tube smooth movement
Tightness/binding/rough spots ®
Repeat the steps 2 to 12.
14. Compress the front fork fully.
15. Fill:
lFront fork oil
Until outer tube top surface with recom-
mended fork oil 1.
ACHTUNG:CAUTION:
lBe sure to use recommended fork oil. If
other oils are used, they may have an
excessively adverse effect on the front
fork performance.
lNever allow foreign materials to enter the
front fork.
Recommended oil:
Suspension oil “01”
16. After filling, pump the damper rod 1
slowly up and down more than 10 times
to distribute the fork oil.
17. Fill:
lFront fork oil
Until outer tube top surface with recom-
mended fork oil once more.
18. After filling, pump the outer tube 1 slowly
up and down (about 200 mm (7.9 in)
stroke) to distribute the fork oil once
more.
NOTE:
Be careful not to excessive full stroke. A stroke
of 200 mm (7.9 in) or more will cause air to
enter. In this case, repeat the steps 15 to 18.

5 - 36
CHASFRONT FORK
19. Wait ten minutes until the air bubbles
have been removed from the front fork,
and the oil has dispense evenly in system
before setting recommended oil level.
NOTE:
Fill with the fork oil up to the top end of the
outer tube, or the fork oil will not spread over to
every part of the front forks, thus making it
impossible to obtain the correct level.
Be sure to fill with the fork oil up to the top of
the outer tube and bleed the front forks.
20. Measure:
lOil level (left and right) a
Out of specification ® Adjust.
NOTE:
Be sure to install the spring guide 2 when
checking the oil level.
WARNING
Never fail to make the oil level adjustment
between the maximum and minimum level
and always adjust each front fork to the
same setting. Uneven adjustment can
cause poor handling and loss of stability.
Standard oil level:
140 mm (5.51 in)
Extent of adjustment:
80 ~ 150 mm (3.15 ~ 5.91 in)
From top of outer tube with
inner tube and damper rod 1
fully compressed without
spring.

–+ELEC

6 - 3
IGNITION SYSTEM
EC620000
IGNITION SYSTEM
INSPECTION STEPS
Use the following steps for checking the possibility of the malfunctioning engine being attributable to
ignition system failure and for checking the spark plug which will not spark.
*marked: Only when the ignition checker is used.
NOTE:

l
Remove the following parts before inspection.
1) Seat
2) Fuel tank
l
Use the following special tools in this inspection.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754
Pocket tester:
YU-3112-C/90890-03112
Spark gap test*Clean or replace
spark plug.
Check entire ignition
system for connection.Repair or replace.
Check engine stop switch. Replace.
Check ignition coil. Primary coil Replace.
Secondary coil Replace.
Check CDI magneto. Pickup coil Replace.
Charging coil Replace.
Check neutral switch. Repair or replace.
Replace CDI unit.
No spark
OK
OK
OK
OK
OK
Spark
No good
No good
No good
No good
No good
No good
No good

6 - 6
–+ELECIGNITION SYSTEM
2. Inspect:
lCharging coil 1 resistance
Out of specification ® Replace.
3. Inspect:
lCharging coil 2 resistance
Out of specification ® Replace. Tester (+) lead ® Brown lead 1
Tester (–) lead ® Green lead 2
Charging coil 1
resistanceTester selector
position
720 ~ 1,080 W
at 20 ˚C (68 ˚F)W ´ 100
Tester (+) lead ® Pink lead 1
Tester (–) lead ® Black lead 2
Charging coil 2
resistanceTester selector
position
44 ~ 66 W at
20 ˚C (68 ˚F)W ´ 10
NEUTRAL SWITCH INSPECTION
1. Inspect:
lNeutral switch conduct
No continuous while in neutral ® Replace.
Continuous while in gear ® Replace.
EC628000
CDI UNIT INSPECTION
Check all electrical components. If no fault is
found, replace the CDI unit. Then check the
electrical components again.Tester (+) lead ® Sky blue lead 1
Tester (–) lead ® Ground 2
Sb
1Ground
2Tester selec-
tor position
NEUTRALW ´ 1IN GEAR

–+ELEC
6 - 7
THROTTLE POSITION SENSOR SYSTEM
THROTTLE POSITION SENSOR SYSTEM
INSPECTION STEPS
If the throttle position sensor will not operate, use the following inspection steps.
*marked: Refer to “IGNITION SYSTEM” section.
NOTE:
lRemove the following parts before inspection.
1) Seat
2) Fuel tank
lUse the following special tools in this inspection.
Pocket tester:
YU-3112-C/90890-03112Inductive tachometer:
YU-08036-B
Engine tachometer:
90890-03113
Check entire ignition
system for connection.Repair or replace.
Check throttle position
sensor.Throttle posi-
tion sensor coilReplace.
*Check CDI magneto. Charging coil Replace.
Check CDI unit.Throttle posi-
tion sensor
input voltageReplace.
OK
OK
OK
No good
No good
No good
No good

6 - 8
–+ELECTHROTTLE POSITION SENSOR SYSTEM
EC624000
COUPLERS AND LEADS CONNECTION
INSPECTION
1. Check:
lCouplers and leads connection
Rust/dust/looseness/short-circuit ®
Repair or replace.
THROTTLE POSITION SENSOR COIL
INSPECTION
1. Inspect:
lThrottle position sensor coil resistance
Out of specification ® Replace.
2. Loosen:
lThrottle stop screw 1
NOTE:
Turn out the throttle stop screw until the throt-
tle shaft is in the full close position.Tester (+) lead ® Blue lead 1
Tester (–) lead ® Black lead 2
Throttle posi-
tion sensor coil
resistanceTester selector
position
4 ~ 6 kW at
20 ˚C (68 ˚F)kW ´ 1
3. Inspect:
lThrottle position sensor coil variable
resistance
Check that the resistance in increased
as the throttle grip is moved from the
full close position to the full open posi-
tion.
Out of specification ® Replace.
Tester (+) lead ® Yellow lead 1
Tester (–) lead ® Black lead 2
Throttle position sen-
sor coil variable
resistanceTester
selector
position
Full closedFull opened
kW ´ 1 Zero ~ 3 kW
at 20 ˚C
(68 ˚F)4 ~ 6 kW at
20 ˚C
(68 ˚F)

7 - 21
TUNSETTING
EC72H002
Suspension setting
lFront fork
NOTE:
lIf any of the following symptoms is experienced with the standard position as the base, make
resetting by reference to the adjustment procedure given in the same chart.
lBefore any change, set the rear shock absorber sunken length to the standard figure 90 ~
100 mm (3.5 ~ 3.9 in).
SymptomSection
Check Adjust
JumpLarge
gapMedium
gapSmall
gap
Stiff over entire range
CCC
Compression damping
Oil level (oil amount)
SpringTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Decrease oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).
Replace with soft spring.
Unsmooth movement
over entire range
CCCC
Outer tube
Inner tube
Under bracket tightening
torqueCheck for any bends, dents, and other noticeable
scars, etc. If any, replace affected parts.
Retighten to specified torque.
Poor initial
movement
C
Rebound damping
Oil sealTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Apply grease in oil seal wall.
Soft over entire range,
bottoming out
CC
Compression damping
Oil level (oil amount)
SpringTurn adjuster clockwise (about 2 clicks) to increase
damping.
Increase oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).
Replace with stiff spring.
Stiff toward stroke end
COil level (oil amount) Decrease oil level by about 5 mm (0.2 in).
Soft toward stroke end,
bottoming out
COil level (oil amount) Increase oil level by about 5 mm (0.2 in).
Stiff initial movement
CCCCCompression dampingTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Low front, tending to
lower front posture
CC
Compression damping
Rebound damping
Balance with rear end
Oil level (oil amount)Turn adjuster clockwise (about 2 clicks) to increase
damping.
Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 95 ~ 100 mm (3.7 ~ 3.9 in) when
one passenger is astride seat (lower rear posture).
Increase oil level by about 5 mm (0.2 in).
“Obtrusive” front, tend-
ing to upper front pos-
ture
CC
Compression damping
Balance with rear end
Spring
Oil lever (oil amount)Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 90 ~ 95 mm (3.5 ~ 3.7 in) when
one passenger is astride seat (upper rear posture).
Replace with soft spring.
Decrease oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).