2010 YAMAHA YZ250F checking oil

5-33
SWINGARM
HANDLING NOTE
Support the machine securely so
there is no danger of it falling over.
REMOVING THE BEARING
1. Remove:• Bearing "1"
Remove the bearing by pressing its
outer race.
CHECKING THE SWINGARM
1. Inspect:• Bearing "1"
• Bushing "2"
Free play exists/unsmooth revolu-
tion/rust →Replace bearing and
bushing as a set.
2. Inspect: • Oil seal "3"Damage →Replace.
CHECKING THE RELAY ARM
1. 5294Inspect: • Bearing "1"
•Collar "2"
Free play exists/unsmooth revolu-
tion/rust → Replace bearing and
collar as a set.
2. Inspect: • Oil seal "3"Damage →Replace. CHECKING THE CONNECTING
ROD
1. Inspect:
•Bearing "1"
• Collar "2"Free play exists/unsmooth revolu-
tion/rust → Replace bearing and
collar as a set.
2. Inspect: • Oil seal "3"
Damage →Replace.
INSTALLING THE BEARING AND
OIL SEAL
1. Install: •Bearing "1"
• Oil seal "2"To swingarm.
• Apply the molybdenum disulfide
grease on the bearing when install-
ing.
• Install the bearing by pressing it on
the side having the manufacture's
marks or numbers.
• First install the outer and then the
inner bearings to a specified depth
from inside.
2. Install: • Bearing "1"
• Washer "2"
• Oil seal "3"To relay arm.
• Apply the molybdenum disulfide grease on the bearing when install-
ing.
• Install the bearing by pressing it on the side having the manufacture's
marks or numbers.
• Apply the molybdenum disulfide grease on the washer.
3. Install:• Bearing "1"
• Oil seal "2"To connecting rod.
• Apply the molybdenum disulfide grease on the bearing when install-
ing.
• Install the bearing by pressing it on the side having the manufacture's
marks or numbers.
Installed depth of bear-
ings:
Outer "a": Zero mm
(Zero in)
Inner "b": 6.5 mm (0.26
in)
Installed depth of bear-
ings "a": Zero mm (Zero in)
Installed depth of bear-
ings "a": Zero mm (Zero in)

5-37
REAR SHOCK ABSORBER
HANDLING NOTE
• Support the machine securely so there is no danger of it falling
over.
• This rear shock absorber is pro-
vided with a separate type tank
filled with high-pressure nitro-
gen gas. To prevent the danger
of explosion, read and under-
stand the follow ing information
before handling the shock ab-
sorber. The manufacturer can
not be held responsible for prop-
erty damage or personal injury
that may result from improper
handling.
• Never tamper or attempt to dis-
assemble the cylinder or the
tank.
• Never throw the rear shock ab-
sorber into an open flame or
other high heat. The rear shock
absorber may explode as a re-
sult of nitrogen gas expansion
and/ or damage to the hose.
• Be careful not to damage any
part of the gas tank. A damaged
gas tank will impair the damp-
ing performance or cause a
malfunction.
• Take care not to scratch the
contact surface of the piston
rod with the cylinder; or oil
could leak out.
• Never attempt to remove the plug at the bottom of the nitro-
gen gas tank. It is very danger-
ous to remove the plug.
• When scrapping the rear shock absorber, follow the instruc-
tions on disposal.
NOTES ON DISPOSAL (YAMAHA
DEALERS ONLY)
Before disposing the rear shock ab-
sorber, be sure to extract the nitrogen
gas from valve "1". Wear eye protec-
tion to prevent eye damage from es-
caping gas and/or metal chips.
To dispose of a damaged or worn-
out rear shock absorber, take the
unit to your Yamaha dealer for this
disposal procedure.
REMOVING THE BEARING
1. Remove:
• Stopper ring (upper bearing) "1"
Press in the bearing while pressing its
outer race and remove the stopper
ring.
2. Remove:• Upper bearing "1"
Remove the bearing by pressing its
outer race.
3. Remove:
• Lower bearing "1"
Remove the bearing by pressing its
outer race.
CHECKING THE REAR SHOCK
ABSORBER
1. Inspect:• Damper rod "1"
Bends/damage →Replace rear
shock absorber assembly.
• Shock absorber "2"
Oil leaks →Replace rear shock
absorber assembly.
Gas leaks →Replace rear shock
absorber assembly.
• Spring "3" Damage →Replace spring.
Fatigue →Replace spring.
Move spring up and down.
• Spring guide "4"
Wear/damage →Replace spring
guide.
• Bearing "5" Free play exists/unsmooth revolu-
tion/rust →Replace.

6-3
IGNITION SYSTEM
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.
• Remove the following parts before inspection.
1. Seat
2. Fuel tank
• Use the following special tools in this inspection.
Spark gap test Spark→ *Clean or replace spark plug.
No spark ↓
Check entire ignition system for connection.
(couplers, leads and ignition coil) No good
→
Repair or replace.
OK ↓
Check engine stop switch. No good→Replace.
OK ↓
Check ignition coil. (primary coil and secondary
coil) No good
→
Replace.
OK ↓
Check CDI magneto. (pickup coil and charging
coil) No good
→
Replace.
OK ↓
Check neutral switch. No good→Repair or replace.
OK ↓
Replace CDI unit.
Dynamic spark tester: YM-34487
Ignition checker:
90890-06754
Pocket tester:
YU-3112-C/90890-03112

6-4
IGNITION 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" (ignition ch ecker "2") as
shown.
• Ignition coil "3"
• Spark plug "4"
A. For USA and CDN
B. Except 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)
CHECKING THE COUPLERS,
LEADS AND IGNITION COIL
CONNECTION
1. Check: • Couplers and leads connection
Rust/dust/looseness/short-circuit
→ Repair or replace.
• Ignition coil and spark plug as
they are fitted
Push in the ignition coil until it
closely contacts the spark plug
hole in the cylinder head cover. CHECKING THE ENGINE STOP
SWITCH
1. Inspect:
• Engine stop switch conduction
Not conductive while it is pushed →
Replace.
Conductive while it is freed →Re-
place.
Set the tester selection position to " Ω
× 1".
CHECKING THE IGNITION COIL
1. Remove the ignition coil cap.
2. Inspect: • Primary coil resistance
Out of specification →Replace. 3. Inspect:
• Secondary coil resistanceOut of specification →Replace.
4. Inspect: • Sealed portion of ignition coil "a"
• Spark plug terminal pin "b"
• Threaded portion of spark plug "c"Wear →Replace.
CHECKING THE CDI MAGNETO
1. Inspect: • Pickup coil resistance
Out of specification →Replace.
Minimum spark gap:
6.0 mm (0.24 in)
Tester (+) lead →Black/White lead
"1"
Tester (-) lead →Black lead "2"
Result Conductive (while the
engine stop switch is
pushed)
Tester (+) lead →Orange lead "1"
Tester (-) lead →Black lead "2"
Primary
coil resis-
tance Tester se-
lector posi-
tion
0.08–0.10
Ω at 20 °C (68 °F) Ω × 1
/W
BB
Tester (+) lead →Orange lead "1"
Tester (-) lead →Spark plug termi-
nal "2"
Secondary coil resis- tance Tester se-
lector posi- tion
4.6–6.8
k Ωat 20 °C
(68 °F) k
Ω × 1
Tester (+) lead →Red lead "1"
Tester (-) lead →White lead "2"
Pickup coil resistance Tester se-
lector posi-
tion
248-372 Ω
at 20 °C (68 °F) Ω
×100
B
WBr
G P
R

6-5
IGNITION SYSTEM
2. Inspect:• Charging coil 1 resistanceOut of specification →Replace.
3. Inspect: • Charging coil 2 resistanceOut of specification →Replace. CHECKING THE NEUTRAL
SWITCH
1. Inspect:
• Neutral switch conduction
Not conductive while it is in neutral →
Replace.
Conductive while it is engaged →Re-
place.
Set the tester selection position to " Ω
× 1".
CHECKING THE CDI UNIT
Check all electrical components. If no
fault is found, replace the CDI unit.
Then check the electrical compo-
nents again.
Tester (+) lead
→Brown lead "1"
Tester (-) lead →Green lead "2"
Charging
coil 1 resis- tance Tester se-
lector posi- tion
720-1,080
Ω at 20 °C
(68 °F) Ω
×100
Tester (+) lead →Pink lead "1"
Tester (-) lead →Black lead "2"
Charging
coil 2 resis- tance Tester se-
lector posi- tion
44-66 Ω at
20 °C (68 °F) Ω ×10
B
WBr
G P
R
B
WBr
GP
R
Tester (+) lead →Sky blue lead "1"
Tester (-) lead →Ground "2"
Result Conductive (while gear
is in neutral)

6-7
THROTTLE POSITION SENSOR SYSTEM
HANDLING NOTE
Do not loosen the screw (throttle
position sensor) "1" except when
changing the throttle position sen-
sor due to failure because it will
cause a drop in engine perfor-
mance.
CHECKING THE COUPLERS AND
LEADS CONNECTION
1. Check: • Couplers and leads connectionRust/dust/looseness/short-circuit
→ Repair or replace.
CHECKING THE THROTTLE
POSITION SENSOR COIL
1. Inspect: • Throttle position sensor coil resis-tance
Out of specification →Replace.
2. Loosen: • Throttle stop screw "1"
Turn out the throttle stop screw until
the throttle shaft is in the full close po-
sition.
3. Inspect:• Throttle position sensor coil vari-able resistance
Check that the resistance in in-
creased as the throttle grip is
moved from the full close position
to the full open position.
Out of specification →Replace.
CHANGING AND ADJUSTING THE
THROTTLE POSI TION SENSOR
1. Remove: • Throttle position sensor coupler
• Carburetor
2. Remove: • Screw (throttle position sensor) "1"
• Throttle position sensor "2"
Loosen the screw (throttle position
sensor) using the T25 bit.
3. Replace: • Throttle position sensor 4. Install:
• Throttle position sensor "1"
• Screw (throttle position sensor) "2"
• Align the slot "a" in the throttle posi-
tion sensor with the projection "b"
on the carburetor.
• Temporarily tighten the screw
(throttle position sensor).
5. Install:•Carburetor
• Throttle position sensor coupler
6. Adjust: • Engine idling speed
Refer to "ADJUSTING THE EN-
GINE IDLING SPEED" section in
the CHAPTER 3.
7. Insert the thin electric conductors "2" (lead) into the throttle position
sensor coupler "1", as shown, and
connect the tester to them.
• Do not insert the electric conduc-
tors more than required because
it may reduce the waterproof
function of the coupler.
• Make sure that a short-circuit does not develop between the
terminals because it may cause
damage to electrical compo-
nents.
Tester (+) lead →Blue lead "1"
Tester (-) lead →Black lead "2"
Throttle po- sition sen-
sor coil
resistance Tester se-
lector posi- tion
4–6 k Ω at
20°C (68 °F) k
Ω×1
Y
B
L
Tester (+) lead
→Yellow lead "1"
Tester (-) lead →Black lead "2"
Throttle position sensor coil vari- able resistance Tes-
ter se-
lector posi- tion
Full
closed Full
opened
kΩ×1
Zero –3
kΩat
20°C
(68 °F) 4–6
k Ωat
20 °C
(68 °F)
Y
B
L
Tester (+) lead
→Yellow lead "3"
Tester (-) lead →Black lead "4"