2006 YAMAHA YZ250F check oil

–+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:
•Remove the following parts before inspection.
1) Seat
2) Fuel tank
•Use the following special tools in this inspection.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754Pocket tester:
YU-3112-C/90890-03112
Spark gap test*Clean or replace
spark plug.
Check entire ignition
system for connection.
(couplers, leads and
ignition coil)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 - 4
–+ELECIGNITION SYSTEM
SPARK GAP TEST
1. Disconnect the ignition coil from spark
plug.
2. Remove the ignition coil cap.
3. Connect the dynamic spark tester 1 (igni-
tion checker 2) as shown.
•Ignition coil 3
•Spark plug 4
ÈFor USA and CDN
ÉExcept for USA and CDN
4. Kick the kickstarter crank.
5. Check the ignition spark gap.
6. Start engine, and increase spark gap until
misfire occurs. (for USA and CDN only)
Minimum spark gap:
6.0 mm (0.24 in)
È
É
COUPLERS, LEADS AND IGNITION COIL
CONNECTION INSPECTION
1. Check:
•Couplers and leads connection
Rust/dust/looseness/short-circuit →
Repair or replace.
•Ignition coil and spark plug as they are fit-
ted
Push in the ignition coil until it closely
contacts the spark plug hole in the cylin-
der head cover.
ENGINE STOP SWITCH INSPECTION
1. Inspect:
•Engine stop switch conduct
No continuous while being pushed → Replace.
Continuous while being freed → Replace. Tester (+) lead
→ Black/White lead
1
Tester (–) lead
→ Black lead
2
B/W
1 B
2 Tester selec-
tor position
PUSH IN
Ω
× 1
FREE1 2
B/W B

6 - 6
–+ELECIGNITION SYSTEM
2. Inspect:
•Charging coil 1 resistance
Out of specification → Replace.
3. Inspect:
•Charging 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
Ω
at 20 °C (68 °F)Ω
× 100
Tester (+) lead
→ Pink lead
1
Tester (–) lead
→ Black lead
2
Charging coil 2
resistanceTester selector
position
44 ~ 66
Ω at
20 °C (68 °F)Ω
× 10
W
RBr
GP
B
2 1
2
1
W
RBr
GP
B
NEUTRAL SWITCH INSPECTION
1. Inspect:
•Neutral 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
1 Ground
2
Tester selec-
tor position
NEUTRAL
Ω
×
×× × 1
IN GEAR
–+ Ω×1
1
2
Sb

–+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:
Use the following special tools in this inspection.
Pocket tester:
YU-3112-C/90890-03112
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
HANDLING NOTE
CAUTION:
Do not loosen the screws (throttle position
sensor)
1 except when changing the throt-
tle position sensor due to failure because it
will cause a drop in engine performance.
1
EC624000
COUPLERS AND LEADS CONNECTION
INSPECTION
1. Check:
•Couplers and leads connection
Rust/dust/looseness/short-circuit →
Repair or replace.
THROTTLE POSITION SENSOR COIL
INSPECTION
1. Inspect:
•Throttle position sensor coil resistance
Out of specification → Replace.
Tester (+) lead
→ Blue lead
1
Tester (–) lead
→ Black lead
2
Throttle posi-
tion sensor coil
resistanceTester selector
position
4 ~ 6 kΩ at
20 °C (68 °F)kΩ × 1
2. Loosen:
•Throttle stop screw 1
NOTE:
Turn out the throttle stop screw until the throt-
tle shaft is in the full close position.

6 - 9
–+ELECTHROTTLE POSITION SENSOR SYSTEM
3. Inspect:
•Throttle 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 position.
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
k
Ω
× 1
Zero ~ 3 k
Ω
at 20 °C
(68°F)4 ~ 6 k
Ω at
20 °C
(68°F)
THROTTLE POSITION SENSOR
REPLACEMENT AND ADJUSTMENT
1. Remove:
•Throttle position sensor coupler
•Carburetor
2. Remove:
•Screw (throttle position sensor) 1
•Throttle position sensor 2
NOTE:
Loosen the screws (throttle position sensor)
using the T25 bit.
3. Replace:
•Throttle position sensor
2
1
4. Install:
•Throttle position sensor 1
•Screw (throttle position sensor) 2
NOTE:
•Align the slot a in the throttle position sensor
with the projection b on the carburetor.
•Temporarily tighten the screws (throttle posi-
tion sensor).
b
a
2 1

7 - 20
TUNSETTING
EC72H002
Suspension setting
•Front fork
NOTE:
•If 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.
•Before 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 rangeCompression damping Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Oil amount Decrease oil amount by about 5 ~ 10 cm
3 (0.2 ~
0.4 Imp oz, 0.2 ~ 0.3 US oz).
Spring Replace with soft spring.
Unsmooth movement
over entire rangeOuter tube Check for any bends, dents, and other noticeable
scars, etc. If any, replace affected parts.
Inner tube
Slide metal Replace with a new one for extended use.
Piston metal Replace with a new one for extended use.
Under bracket tightening
torqueRetighten to specified torque.
Poor initial
movementRebound damping Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Oil seal Apply grease in oil seal wall.
Soft over entire
range, bottoming outCompression damping Turn adjuster clockwise (about 2 clicks) to increase
damping.
Oil amount Increase oil amount by about 5 ~ 10 cm
3 (0.2 ~ 0.4
Imp oz, 0.2 ~ 0.3 US oz).
Spring Replace with stiff spring.
Stiff toward stroke
endOil amountDecrease oil amount by about 5 cm
3 (0.2 Imp oz,
0.2 US oz).
Soft toward stroke
end, bottoming outOil amountIncrease oil amount by about 5 cm
3 (0.2 Imp oz,
0.2 US oz).
Stiff initial movement Compression dampingTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Low front, tending to
lower front postureCompression damping Turn adjuster clockwise (about 2 clicks) to increase
damping.
Rebound damping Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Balance with rear end Set sunken length for 95 ~ 100 mm (3.7 ~ 3.9 in)
when one passenger is astride seat (lower rear pos-
ture).
Oil amount Increase oil amount by about 5 cm
3 (0.2 Imp oz,
0.2 US oz).
“Obtrusive” front,
tending to upper front
postureCompression damping Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Balance with rear end Set sunken length for 90 ~ 95 mm (3.5 ~ 3.7 in)
when one passenger is astride seat (upper rear pos-
ture).
Spring Replace with soft spring.
Oil amount Decrease oil amount by about 5 ~ 10 cm
3 (0.2 ~ 0.4
Imp oz, 0.2 ~ 0.3 US oz).