2002 YAMAHA YZ250F fuel

SPEC
2 - 15
MAINTENANCE SPECIFICATIONS
NOTE:
- marked portion shall be checked for torque tightening after break-in or before each race.Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Nipple (spoke)—72 3 0.3 2.2
Rear wheel sprocket M8 × 1.25 6 42 4.2 30
Rear brake disc cover M6 × 1.0 2 7 0.7 5.1
Rear brake caliper protector M6 × 1.0 2 7 0.7 5.1
Engine mounting:
Engine and engine bracket (front) M10 × 1.25 1 69 6.9 50
Engine and frame (lower) M10 × 1.25 1 69 6.9 50
Engine bracket and frame M8 × 1.25 6 34 3.4 24
Engine and engine bracket (upper) M10 × 1.25 1 55 5.5 40
Lower engine guard M6 × 1.0 3 10 1.0 7.2
Right engine guard M8 × 1.25 2 10 1.0 7.2
Pivot shaft and nut M16 × 1.5 1 85 8.5 61
Relay arm and swingarm M14 × 1.5 1 80 8.0 58
Relay arm and connecting rod M14 × 1.5 1 80 8.0 58
Connecting rod and frame M14 × 1.5 1 80 8.0 58
Rear shock absorber and frame M10 × 1.25 1 56 5.6 40
Rear shock absorber and relay arm M10 × 1.25 1 53 5.3 38
Rear frame M8 × 1.25 3 29 2.9 21
Swingarm and brake hose holder M5 × 0.8 4 1 0.1 0.7
Swingarm and patch M4 × 0.7 4 2 0.2 1.4
Upper drive chain tensioner M8 × 1.25 1 19 1.9 13
Lower drive chain tensioner M8 × 1.25 1 20 2.0 14
Drive chain case M6 × 1.0 3 7 0.7 5.1
Seal guard and swingarm M5 × 0.8 4 6 0.6 4.3
Fuel tank M6 × 1.0 2 10 1.0 7.2
Fuel cock M6 × 1.0 2 7 0.7 5.1
Seat set bracket and fuel tank M6 × 1.0 1 7 0.7 5.1
Hooking screw (fitting band) and fuel tank M6 × 1.0 1 7 0.7 5.1
Radiator cover M6 × 1.0 6 4 0.4 2.9
Front fender M6 × 1.0 4 7 0.7 5.1
Rear fender M6 × 1.0 4 7 0.7 5.1
Side cover M6 × 1.0 2 7 0.7 5.1
Seat M8 × 1.25 2 23 2.3 17
Number plate M6 × 1.0 1 7 0.7 5.1

2 - 18
SPEC

CABLE ROUTING DIAGRAM
EC240000
CABLE ROUTING DIAGRAM
1
Hose guide
2
Brake hose
3
Fuel tank breather hose
4
Engine stop switch lead
5
Oil tank breather hose
6
Sub-wire harness
7
Neutral switch lead
8
Cable guide
9
Cylinder head breather hose
0
CDI magneto lead
A
Radiator breather hose
B
Carburetor breather hose
C
Carburetor overflow hose
D
Ignition coil lead
E
CDI unit lead
Å
Pass the fuel tank breather hose
between the handlebar and ten-
sion bar, then insert its end into
the hole of the number plate.
ı
Fasten the engine stop switch
lead and ignition coil lead of the
sub-wire harness.
Ç
Fasten the sub-wire harness
and engine stop switch lead.
Fasten the engine stop switch
lead at its protecting tube.
Î
Fasten the sub-wire harness.
‰
Pass the sub-wire harness
between the upper engine
brackets.
Ï
Fasten the sub-wire harness at
its white tape.
Ì
Fasten the sub-wire harness.
Ó
Make sure that the throttle posi-
tion sensor lead coupler does
not go out side the chassis.
È
Fasten the throttle position sen-
sor lead.
Ô
Pass the carburetor breather
hose and overflow hose
between the connecting rod and
cross tube (frame).

Fasten the neutral switch lead
on the oil hose with a plastic
locking tie and cut off the tie
end.
Ò
Pass the clutch cable through
the cable guide.
˜
Pass the cylinder head breather
hose through the hose guide.
ˆ
Fasten the neutral switch lead.

3 - 2
INSP
ADJ

MAINTENANCE INTERVALS
SHIFT FORK, SHIFT CAM, GUIDE BAR
Inspect
●
Inspect wear
ROTOR NUT
Retighten
●

●

EXHAUST PIPE, SILENCER, PRO-
TECTOR
Inspect and retighten
Clean
Replace
●

●

●

●
* Whichever comes first
CRANK
Inspect and clean
●

●

CARBURETOR
Inspect, adjust and clean
●

●
When using a high-pres-
sure washer, make sure
that water does not enter
the accelerator pump.
SPARK PLUG
Inspect and clean
Replace
●

●

●

DRIVE CHAIN
Lubricate, slack, alignment
Replace
●

●

●
Use chain lube
Chain slack: 40 ~ 50 mm
(1.6 ~ 2.0 in)
COOLING SYSTEM
Check coolant level and leakage
Check radiator cap operation
Replace coolant
Inspect hoses
●

●

●

●

●
Every two years
OUTSIDE NUTS AND BOLTS
Retighten
●

●
Refer to “STARTING
AND BREAK-IN” section
in the CHAPTER 1.
AIR FILTER
Clean and lubricate
Replace
●

●

●
Use foam air-filter oil
FRAME
Clean and inspect
●

●

FUEL TANK, COCK
Clean and inspect
●

●

BRAKES
Adjust lever position and pedal height
Lubricate pivot point
Check brake disc surface
Check fluid level and leakage
Retighten brake disc bolts, caliper
bolts, master cylinder bolts and union
bolts
Replace pads
Replace brake fluid
●

●

●

●

●

●

●

●

●

●

●

●
Every one year
FRONT FORKS
Inspect and adjust
Replace oil
Replace oil seal
●

●

●

●

●
Suspension oil “01” ItemAfter
break-inEvery
race
Every
third
(or
500 km)Every
fifth
(or
1,000 km)
As re-
quiredRemarks


3

3 - 4
INSP
ADJ
PRE-OPERATION INSPECTION AND MAINTENANCE
EC320000
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation, practice or a race, make sure the machine is in good operating
condition.
Before using this machine, check the following points.
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
CoolantCheck that coolant is filled up to the radiator cap.
Check the cooling system for leakage.P.3-5 ~ 9
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the
fuel line for leakage.P.1-14
Engine oilCheck that the oil level is correct. Check the crankcase and
frame oil line for leakage.P.3-13 ~ 17
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-9
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-10 ~ 11
Brakes Check the play of front brake and effect of front and rear brake. P.3-25 ~ 31
Drive chainCheck drive chain slack and alignment. Check that the drive
chain is lubricated properly.P.3-32 ~ 34
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-42 ~ 43
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-43 ~ 44
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage. P.3-34 ~ 41
Cables (wires)Check that the clutch and throttle cables move smoothly. Check
that they are not caught when the handlebars are turned or
when the front forks travel up and down.—
Exhaust pipeCheck that the exhaust pipe is tightly mounted and has no
cracks.P.4-2
Rear wheel sprocket Check that the rear wheel sprocket tightening bolt is not loose. P.3-32
Lubrication Check for smooth operation. Lubricate if necessary. P.3-45
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-19
Lead connectorsCheck that the CDI magneto, CDI unit, and ignition coil are con-
nected tightly.P.1-6
SettingsIs the machine set suitably for the condition of the racing course
and weather or by taking into account the results of test runs
before racing? Are inspection and maintenance completely
done?P.7-1 ~ 22

3 - 18
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:
18 Nm (1.8 m • kg, 13 ft • lb)
PILOT SCREW ADJUSTMENT
1. Adjust:
Pilot screw 1
*For EUROPEAdjustment 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:
1-5/8 turns out
* 1-1/2 turns out
(example)
OIL PRESSURE INSPECTION/
PILOT SCREW ADJUSTMENT

3 - 19
INSP
ADJ
ENGINE IDLING SPEED ADJUSTMENT
1. Start the engine and thoroughly warm it
up.
2. Attach:
Inductive tachometer
To spark plug lead.
3. Adjust:
Engine idling speed
Adjustment steps:
Adjust the pilot screw.
Refer to “PILOT SCREW ADJUSTMENT”
section.
Turn the throttle stop screw 1 until the
engine runs at the lowest possible speed.
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.
Inductive tachometer:
YU-8036-B
Engine tachometer:
90890-03113
Engine idling speed:
1,900 ~ 2,100 r/min
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 CHAP-
TER 4.
2. Drain:
Coolant
Refer to “COOLANT REPLACEMENT”
section.
ENGINE IDLING SPEED ADJUSTMENT/
VALVE CLEARANCE INSPECTION AND ADJUSTMENT

3 - 44
INSP
ADJ
STEERING HEAD INSPECTION AND ADJUSTMENT
Tighten the steering ring nut 3 using
steering nut wrench 4.
NOTE:
Set the torque wrench to the steering nut
wrench so that they form a right angle.
Steering nut wrench:
YU-33975/90890-01403
T R..
Steering ring nut (initial tighten-
ing):
38 Nm (3.8 m • kg, 27 ft • lb)
Loosen the steering ring nut one turn.
Retighten the steering ring nut using the
steering nut wrench.
WARNING
Avoid over-tightening.
T R..
Steering ring nut (final tighten-
ing):
7 Nm (0.7 m • kg, 5.1 ft • lb)
Check the steering stem by turning it lock
to lock. If there is any binding, remove the
steering stem assembly and inspect the
steering bearings.
Install the upper bracket 5, steering stem
nut 6, handlebar 7, handlebar upper
holder 8 and number plate 9.
NOTE:
The upper handlebar holder should be
installed with the punched mark a for-
ward.
Insert the end of fuel breather hose 0 into
the hole of the number plate.
CAUTION:
First tighten the bolts on the front side of
the handlebar holder, and then tighten
the bolts on the rear side.
T R..
Steering stem nut:
145 Nm (14.5 m • kg, 105 ft • lb)
Handlebar upper holder:
28 Nm (2.8 m • kg, 20 ft • lb)
Pinch bolt (upper bracket):
23 Nm (2.3 m • kg, 17 ft • lb)
Number plate:
7 Nm (0.7 m • kg, 5.1 ft • lb)

4 - 1
ENG

EC400000
ENGINE
SEAT, FUEL TANK AND SIDE COVERS
Extent of removal:
1
Seat removal
2
Fuel tank removal
3
Side covers removal
4
Number plate removal
Extent of removal Order Part name Q’ty Remarks
Preparation for removal
SEAT, FUEL TANK AND SIDE
COVERS REMOVAL
Turn the fuel cock to “OFF”.
Disconnect the fuel hose.
1 Seat 1
2 Air scoop (left and right) 2
3 Fitting band 1 Remove on fuel tank side.
4 Bolt (fuel tank) 2
5 Fuel tank 1
6 Left side cover 1
7 Right side cover 1
8 Number plate 1
13
4
2
3

SEAT, FUEL TANK AND SIDE COVERS
4