check oil YAMAHA YZ250F 2006 Owner's Manual

4 - 102
ENGTRANSMISSION, SHIFT CAM AND SHIFT FORK
5. Install:
Shift fork 1 (L) 1
Shift fork 2 (C) 2
Shift fork 3 (R) 3
Shift cam 4
To main axle and drive axle.
NOTE:
Apply the molybdenum disulfide oil on the
shift fork grooves.
Mesh the shift fork #1 (L) with the 4th wheel
gear 5 and #3 (R) with the 5th wheel gear 7
on the drive axle.
Mesh the shift fork #2 (C) with the 3rd pinion
gear 6 on the main axle.
6. Install:
Transmission assembly 1
To left crankcase 2.
NOTE:
Apply the engine oil on the bearings and guide
bars.
7. Check:
Shifter operation
Transmission operation
Unsmooth operation → Repair.

5 - 35
CHAS
9. Check that the damper assembly is fully
stretched. Not fully stretched → Repeat the
steps 2 to 8.
10. Tighten:
Base valve 1
NOTE:
Hold the damper assembly with the cap bolt
ring wrench 2 and use the cap bolt wrench 3
to tighten the base valve with specified torque.
Cap bolt wrench:
YM-01500/90890-01500
Cap bolt ring wrench:
YM-01501/90890-01501
T R..29 Nm (2.9 m · kg, 21 ft · lb)
11. After filling, pump the damper assembly 1
slowly up and down more than 10 times to
distribute the fork oil.
12. While protecting the damper assembly 1
with a rag and compressing fully, allow
excessive oil to overflow on the base valve
side.
CAUTION:
Take care not to damage the damper
assembly.
13. Allow the overflowing oil to escape at the
hole a in the damper assembly.
FRONT FORK

5 - 36
CHASFRONT FORK
14. Check:
Damper assembly smooth movement
Tightness/binding/rough spots → Repeat
the steps 2 to 13.
15. Install:
Dust seal 1
Stopper ring 2
Oil seal 3
Oil seal washer 4
Slide metal 5
To inner tube 6.
NOTE:
Apply the fork oil on the inner tube.
When installing the oil seal, use vinyl seat a
with fork oil applied to protect the oil seal lip.
Install the oil seal with its manufacture’s
marks or number facing the axle holder side.
Install the oil seal washer with its projections
b facing upward.
16. Install:
Piston metal 1
NOTE:
Install the piston metal onto the slot on inner
tube.
17. Install:
Outer tube 1
To inner tube 2.

5 - 59
CHASSWINGARM
3. Install:
•Collar 1
To connecting rod 2.
NOTE:
Apply the molybdenum disulfide grease on the
collar and oil seal lips.
4. Install:
•Connecting rod 1
•Bolt (connecting rod) 2
•Washer 3
•Nut (connecting rod) 4
To relay arm 5.
NOTE:
Apply the molybdenum disulfide grease on the
bolt.
5. Install:
•Relay arm 1
•Bolt (relay arm) 2
•Washer 3
•Nut (relay arm) 4
To swingarm.
NOTE:
•Apply the molybdenum disulfide grease on
the bolt circumference and threaded portion.
•Do not tighten the nut yet.
6. Install:
•Swingarm 1
•Pivot shaft 2
NOTE:
•Apply the molybdenum disulfide grease on
the pivot shaft.
•Insert the pivot shaft from right side.
7. Check:
•Swingarm side play a
Free play exists → Replace thrust bear-
ing.
•Swingarm up and down movement b
Unsmooth movement/binding/rough
spots → Grease or replace bearings,
bushings and collars.
T R..80 Nm (8.0 m · kg, 58 ft · lb)
T R..85 Nm (8.5 m · kg, 61 ft · lb)

–+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