check engine YAMAHA YZ250F 2005 User Guide

3 - 10
INSP
ADJTHROTTLE CABLE ADJUSTMENT/
THROTTLE LUBRICATION
THROTTLE CABLE ADJUSTMENT
1. Check:
Throttle grip free play a
Out of specification → Adjust.
Throttle grip free play
a:
3 ~ 5 mm (0.12 ~ 0.20 in)
2. Adjust:
Throttle grip free play
Throttle grip free play adjustment steps:
Slide the adjuster cover.
Loosen the locknut 1.
Turn the adjuster 2 until the specified free
play is obtained.
Tighten the locknut.
NOTE:
Before adjusting the throttle cable free play,
the engine idle speed should be adjusted.
WARNING
After adjusting, turn the handlebar to
right and left and make sure that the
engine idling does not run faster.
21
THROTTLE LUBRICATION
1. Remove:
Cover (throttle cable cap) 1
Cover (grip cap) 2
Throttle grip cap 3
2. Apply:
Lithium soap base grease
On the throttle cable end a.
3. Install:
Throttle grip cap
Screw (throttle grip cap)
Cover (grip cap)
Cover (throttle cable cap)
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)

3 - 11
INSP
ADJHOT STARTER LEVER ADJUSTMENT/
AIR FILTER CLEANING
HOT STARTER LEVER ADJUSTMENT
1. Check:
Hot starter lever free play a
Out of specification → Adjust.
2. Adjust:
Hot starter lever free play
NOTE:
After adjustment, check proper operation of
hot starter.
Hot starter lever free play
a:
3 ~ 6 mm (0.12 ~ 0.24 in)
Hot starter lever free play adjustment
steps:
Loosen the locknut 1.
Turn the adjuster 2 until free play a is
within the specified limits.
Tighten the locknut.
AIR FILTER CLEANING
NOTE:
Proper air filter maintenance is the biggest key
to preventing premature engine wear and
damage.
CAUTION:
Never run the engine without the air filter
element in place; this would allow dirt and
dust to enter the engine and cause rapid
wear and possible engine damage.
1. Remove:
Seat
Fitting bolt 1
Washer 2
Air filter element 3
Air filter guide 4

3 - 16
INSP
ADJ
ENGINE OIL REPLACEMENT
7. If the oil filter is to be replaced during this
oil change, remove the following parts and
reinstall them.
8. Install:
Copper washer 1
Oil strainer (frame) 2
Oil hose 3
Bolt (oil hose) 4
Oil hose clamp 5
Lower engine bracket
9. Install:
Copper washer
Oil filter element drain bolt
Crankcase oil drain bolt
Frame oil drain bolt
10. Fill:
Engine oil
11. Check:
Oil leakage
12. Install:
Oil tank cap
13. Check:
Engine oil level Replacement steps:
Remove the oil filter element cover 1 and
oil filter element 2.
Check the O-rings 3, if cracked or dam-
aged, replace them with a new one.
Install the oil filter element and oil filter ele-
ment cover.
T R..
Oil filter element cover:
10 Nm (1.0 m  kg, 7.2 ft  lb)
Oil quantity:
Periodic oil change:
1.0 L (0.88 Imp qt, 1.06 US qt)
With oil filter replacement:
1.1 L (0.97 Imp qt, 1.27 US qt)
Total amount:
1.2 L (1.06 Imp qt, 1.27 US qt)
T R..70 Nm (7.0 m · kg, 50 ft · lb)
T R..8 Nm (0.8 m · kg, 5.8 ft · lb)
T R..2 Nm (0.2 m · kg, 1.4 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..20 Nm (2.0 m · kg, 14 ft · lb)
T R..23 Nm (2.3 m · kg, 17 ft · lb)

3 - 17
INSP
ADJ
OIL PRESSURE INSPECTION
1. Check:
Oil pressure
Checking steps:
Slightly loosen the oil pressure check bolt
1.
Start the engine and keep it idling until oil
starts to seep from the oil pressure check
bolt. If no oil comes out after one minute,
turn the engine off so it will not seize.
Check oil passages and oil pump for dam-
age or leakage.
Start the engine after solving the prob-
lem(s) and recheck the oil pressure.
Tighten the oil pressure check bolt.
T R..
Oil pressure check bolt:
10 Nm (1.0 m  kg, 7.2 ft  lb)
PILOT SCREW ADJUSTMENT
1. Adjust:
Pilot screw 1
* Except for USAAdjustment steps:
NOTE:
To optimize the fuel flow at a smaller throttle
opening, each machine’s pilot screw has
been individually set at the factory. Before
adjusting the pilot screw, turn it in fully and
count the number of turns. Record this num-
ber as the factory-set number of turns out.
Turn in the pilot screw until it is lightly
seated.
Turn out the pilot screw by the factory-set
number of turns.
Pilot screw:
1-7/8 turns out (example)
* 2-1/8 turns out
OIL PRESSURE INSPECTION/
PILOT SCREW ADJUSTMENT

3 - 18
INSP
ADJ
ENGINE IDLING SPEED ADJUSTMENT
1. Start the engine and thoroughly warm it up.
2. Adjust:
Engine idling speed
Adjustment steps:
Adjust the pilot screw.
Refer to “PILOT SCREW ADJUSTMENT”
section.
Turn the throttle stop screw 1 until the
specified engine idling speed.
NOTE:
Using a digital engine tachometer for idle
speed adjustment, detect the engine idling
speed by bringing the sensing element c of
the engine tachometer close to the ignition
coil 2.
To increase idle speed → Turn the throt-
tle stop screw 1 in a.
To decrease idle speed → Turn the throt-
tle stop screw 1 out b.
Engine idling speed:
1,900 ~ 2,100 r/min
c2
VALVE CLEARANCE INSPECTION AND
ADJUSTMENT
NOTE:
The valve clearance should be adjusted
when the engine is cool to the touch.
The piston must be at Top Dead Center
(T.D.C.) on compression stroke to check or
adjust the valve clearance.
1. Remove:
Seat
Fuel tank
Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section in the CHAPTER 4.
2. Drain:
Coolant
Refer to “COOLANT REPLACEMENT”
section.
ENGINE IDLING SPEED ADJUSTMENT/
VALVE CLEARANCE INSPECTION AND ADJUSTMENT

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INSP
ADJ
VALVE CLEARANCE INSPECTION AND ADJUSTMENT
3. Remove:
Right radiator
Refer to “RADIATOR” section in the
CHAPTER 4.
Carburetor
Refer to “CARBURETOR” section in the
CHAPTER 4.
Spark plug
Upper engine bracket
Cylinder head cover
Refer to “CAMSHAFTS” section in the
CHAPTER 4.
4. Remove:
Timing mark accessing screw 1
Crankshaft end accessing screw 2
O-ring
5. Check:
Valve clearance
Out of specification → Adjust.
Valve clearance (cold):
Intake valve:
0.10 ~ 0.15 mm
(0.0039 ~ 0.0059 in)
Exhaust valve:
0.17 ~ 0.22 mm
(0.0067 ~ 0.0087 in)

3 - 32
INSP
ADJ
DRIVE CHAIN SLACK ADJUSTMENT
4. Check:
Drive chain stiffness a
Clean and oil the drive chain and hold as
illustrated.
Stiff → Replace drive chain.
5. Install:
Drive chain 1
Joint 2
Master link clip 3
CAUTION:
Be sure to install the master link clip to the
direction as shown.
aTurning direction
6. Lubricate:
Drive chain
Drive chain lubricant:
SAE 10W-30 motor oil or
suitable chain lubricants
DRIVE CHAIN SLACK ADJUSTMENT
1. Elevate the rear wheel by placing the suit-
able stand under the engine.
2. Check:
Drive chain slack a
Above the seal guard installation bolt.
Out of specification → Adjust.
NOTE:
Before checking and/or adjusting, rotate the
rear wheel through several revolutions and
check the slack several times to find the tight-
est point. Check and/or adjust the drive chain
slack with the rear wheel in this “tight chain”
position.
Drive chain slack:
48 ~ 58 mm (1.9 ~ 2.3 in)

3 - 42
INSP
ADJ
STEERING HEAD INSPECTION AND ADJUSTMENT
2. Inspect:
Bearing free play
Exist play → Replace.
EC36U013
STEERING HEAD INSPECTION AND
ADJUSTMENT
1. Elevate the front wheel by placing a suit-
able stand under the engine.
2. Check:
Steering stem
Grasp the bottom of the forks and gently
rock the fork assembly back and forth.
Free play → Adjust steering head.
3. Check:
Steering smooth action
Turn the handlebar lock to lock.
Unsmooth action → Adjust steering ring
nut.
4. Adjust:
Steering ring nut
Steering ring nut adjustment steps:
Remove the number plate.
Remove the handlebar and handlebar
upper bracket.
Loosen the steering ring nut 1 using the
steering nut wrench 2.
Steering nut wrench:
YU-33975/90890-01403

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INSP
ADJ
ELECTRICAL/SPARK PLUG INSPECTION
EC370000
ELECTRICAL
EC371001
SPARK PLUG INSPECTION
1. Remove:
Spark plug
2. Inspect:
Electrode 1
Wear/damage → Replace.
Insulator color 2
Normal condition is a medium to light tan
color.
Distinctly different color → Check the
engine condition.
NOTE:
When the engine runs for many hours at low
speeds, the spark plug insulator will become
sooty, even if the engine and carburetor are in
good operating condition.
3. Measure:
Plug gap a
Use a wire gauge or thickness gauge.
Out of specification → Regap.
4. Clean the plug with a spark plug cleaner if
necessary.
Spark plug gap:
0.7 ~ 0.8 mm (0.028 ~ 0.031 in)
5. Tighten:
Spark plug
NOTE:
Before installing a spark plug, clean the gas-
ket surface and plug surface.
Finger-tighten a the spark plug before torqu-
ing to specification b.
T R..13 Nm (1.3 m · kg, 9.4 ft · lb)

3 - 47
INSP
ADJ
IGNITION TIMING CHECK
IGNITION TIMING CHECK
1. Remove:
Timing mark accessing screw 1
2. Attach:
Timing light
Inductive tachometer
To the ignition coil lead (orange lead 1).
Timing light:
YM-33277-A/90890-03141
1
3. Adjust:
Engine idling speed
Refer to “ENGINE IDLING SPEED
ADJUSTMENT” section.
4. Check:
Ignition timing
Visually check the stationary pointer a is
within the firing range b on the rotor.
Incorrect firing range → Check rotor and
pickup assembly.
5. Install:
Timing mark accessing screw