2003 YAMAHA WR 250F engine

GENERAL SPECIFICATIONS
2 - 2
SPEC
Oil capacity:
Engine oil
Periodic oil change 1.2 L (1.06 Imp qt, 1.27 US qt)
With oil filter replacement 1.3 L (1.14 Imp qt, 1.37 US qt)
Total amount 1.4 L (1.23 Imp qt, 1.48 US qt)
Coolant capacity (including all routes): 1.3 L (1.14 Imp qt, 1.37 US qt)
Air filter: Wet type element
Fuel:
Type Premium unleaded gasoline only with a
research octane number of 95 or higher.
(Except for ZA)
Premium gasoline (For ZA)
Tank capacity 10 L (2.2 Imp gal, 2.64 US gal)
Reserve 1.2 L (0.26 Imp gal, 0.32 US gal)
Carburetor:
Type FCR-MX37
Manufacturer KEIHIN
Spark plug:
Type/manufacturer CR8E/NGK (resistance type)
Gap 0.7 ~ 0.8 mm (0.028 ~ 0.031 in)
Clutch type: Wet, multiple-disc
Transmission:
Primary reduction system Gear
Primary reduction ratio 57/17 (3.353)
Secondary reduction system Chain drive
Secondary reduction ratio 52/13 (4.000)
Transmission type Constant mesh, 5-speed
Operation Left foot operation
Gear ratio: 1st 31/13 (2.385)
2nd 28/16 (1.750)
3rd 28/21 (1.333)
4th 25/24 (1.042)
5th 22/27 (0.815)
Chassis:
Frame type Semi double cradle
Caster angle 27.1°
Trail 117.4 mm (4.62 in)
Tire:
Type With tube
Size (front) 80/100-21 51M (For USA, CDN and ZA)
90/90-21 54R (For EUROPE, AUS and NZ)
Size (rear) 100/100-18 59M (For USA, CDN and ZA)
130/90-18 69R (For EUROPE, AUS and NZ)
Tire pressure (front and rear) 100 kPa (1.0 kgf/cm
2, 15 psi)
1
2
3
4
5
6
7

MAINTENANCE SPECIFICATIONS
2 - 4
SPEC
MAINTENANCE SPECIFICATIONS
ENGINE
Item Standard Limit
Cylinder head:
Warp limit ---- 0.05 mm
(0.002 in)
Cylinder:
Bore size 77.00 ~ 77.01 mm
(3.0315 ~ 3.0319 in)----
Out of round limit ---- 0.05 mm
(0.002 in)
Camshaft:
Drive method Chain drive (Left) ----
Camshaft cap inside diameter 22.000 ~ 22.021 mm
(0.8661 ~ 0.8670 in)----
Camshaft outside diameter 21.967 ~ 21.980 mm
(0.8648 ~ 0.8654 in)----
Shaft-to-cap clearance 0.020 ~ 0.054 mm
(0.0008 ~ 0.0021 in)0.08 mm
(0.003 in)
Cam dimensions
Intake“A”30.296 ~ 30.346 mm
(1.1923 ~ 1.1947 in)30.196 mm
(1.1888 in)
“B”22.45 ~ 22.55 mm
(0.8839 ~ 0.8878 in)22.35 mm
(0.8799 in)
Exhaust“A”30.399 ~ 30.499 mm
(1.1968 ~ 1.2007 in)30.299 mm
(1.1929 in)
“B”22.45 ~ 22.55 mm
(0.8839 ~ 0.8878 in)22.35 mm
(0.8799 in)
Camshaft runout limit ---- 0.03 mm
(0.0012 in)
A
B

MAINTENANCE SPECIFICATIONS
2 - 8
SPEC
Clutch:
Friction plate thickness 2.9 ~ 3.1 mm (0.114 ~ 0.122 in) 2.7 mm
(0.106 in)
Quantity 9 ----
Clutch plate thickness 1.1 ~ 1.3 mm (0.043 ~ 0.051 in) ----
Quantity 8 ----
Warp limit ---- 0.1 mm
(0.004 in)
Clutch spring free length 37.0 mm (1.46 in) 36.0 mm
(1.42 in)
Quantity 5 ----
Clutch housing thrust clearance 0.10 ~ 0.35 mm
(0.0039 ~ 0.0138 in)----
Clutch housing radial clearance 0.010 ~ 0.044 mm
(0.0004 ~ 0.0017 in)----
Clutch release method Inner push, cam push ----
Shifter:
Shifter type Cam drum and guide bar ----
Guide bar bending limit ---- 0.05 mm
(0.002 in)
Kickstarter:
Type Kick and ratchet type ----
Carburetor:
USAEUROPE, CDN,
ZA, AUS, NZ
Type/manufacturer FCR-MX37/KEIHIN←
I. D. mark 5UM1 00 5UM2 10
Main jet (M.J) #185 #172
Main air jet (M.A.J)ø2.0←
Jet needle (J.N) OBDVS-4 OBELP-4
Cutaway (C.A) 1.5←
Pilot jet (P.J) #40←
Pilot air jet (P.A.J) #75←
Pilot outlet (P.O)ø0.9←
Pilot screw (example) (P.S) 2 1-7/8
Bypass (B.P)ø1.0←
Valve seat size (V.S)ø3.8←
Starter jet (G.S) #72←
Leak jet (Acc.P) #90←
Float height (F.H) 8 mm (0.31 in)←
Engine idle speed 1,900 ~ 2,100 r/min←
Intake vacuum 26.7 ~ 32.0 kPa
(200 ~ 240 mmHg,
7.87 ~ 9.45 inHg)←
Hot starter lever free play 3 ~ 6 mm
(0.12 ~ 0.24 in)← Item Standard Limit

MAINTENANCE SPECIFICATIONS
2 - 15
SPEC
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 50 5.0 36
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
Drive chain puller adjust bolt and locknut M8 × 1.25 2 16 1.6 11
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
Left engine guard M8 × 1.25 2 23 2.3 17
Right engine guard M8 × 1.25 2 23 2.3 17
Regulator bracket and frame M6 × 1.0 2 7 0.7 5.1
Regulator M6 × 1.0 2 7 0.7 5.1
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 (upper) M8 × 1.25 1 32 3.2 23
Rear frame (lower) M8 × 1.25 2 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 support 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
Air scoop and fuel tank M6 × 1.0 6 4 0.4 2.9
Air scoop and radiator guard (lower) M6 × 1.0 2 4 0.4 2.9
Front fender M6 × 1.0 4 7 0.7 5.1
Rear fender (front) M6 × 1.0 2 7 0.7 5.1
Rear fender (rear) M6 × 1.0 2 10 1.0 7.2
Side cover M6 × 1.0 2 7 0.7 5.1
Seat M8 × 1.25 2 23 2.3 17
Trip meter M6 × 1.0 2 7 0.7 5.1
Meter cable holder and front fork protector M5 × 0.8 2 4 0.4 2.9
Headlight stay (lower) and lower bracket M8 × 1.25 2 7 0.7 5.1

2 - 19
GENERAL TORQUE SPECIFICATIONS/
DEFINITION OF UNITS
SPEC
EC220001
GENERAL TORQUE SPECIFICATIONS
This chart specifies torque for standard fasten-
ers with standard I.S.O. pitch threads. Torque
specifications for special components or
assemblies are included in the applicable sec-
tions of this book. To avoid warpage, tighten
multi-fastener assemblies in a crisscross fash-
ion, in progressive stages, until full torque is
reached. Unless otherwise specified, torque
specifications call for clean, dry threads. Com-
ponents should be at room temperature.
A: Distance between flats
B: Outside thread diameter
EC230000
DEFINITION OF UNITS
A
(Nut)B
(Bolt)TORQUE
SPECIFICATION
Nm mkg ftlb
10 mm
12 mm
14 mm
17 mm
19 mm
22 mm6 mm
8 mm
10 mm
12 mm
14 mm
16 mm6
15
30
55
85
1300.6
1.5
3.0
5.5
8.5
134.3
11
22
40
61
94
Unit Read Definition Measure
mm
cmmillimeter
centimeter10
-3 meter
10-2 meterLength
Length
kg kilogram 10
3 gram Weight
N Newton 1 kg
× m/sec
2 Force
Nm
m  kgNewton meter
Meter kilogramN
× m
m
× kgTorque
Torque
Pa Pascal N/m
2Pressure
N/mm Newton per millimeter N/mm Spring rate
L
cm
3 Liter
Cubic centimeter—
—Volume or capacity
Volume or capacity
r/min Revolution per minute—Engine speed

SPEC
2 - 111
CABLE ROUTING DIAGRAM
1Throttle cable
2Brake hose
3Clamp
4Light switch lead
5Hot starter cable
6Clutch cable
7Hose guide
8Clutch switch lead
9Engine stop switch lead
0Trip meter cable
AMain switch lead
BTrip meter
CMain switchDLight switch
EStart switch lead
ÈFasten the start switch lead and light switch lead.
ÉFasten the engine stop switch lead and clutch switch lead.
ÊPass the brake hose through the hose guide.
ËPass the start switch lead in front of the main switch lead.
ÌFasten the start switch lead.
ÍPass the hot starter cable, clutch cable and light switch lead
between the upper bracket and coupler bracket.
ÎPass the throttle cables between the upper bracket and trip
meter.

3 - 1
INSP
ADJ
MAINTENANCE INTERVALS
EC300000
REGULAR INSPECTION AND ADJUSTMENTS
MAINTENANCE INTERVALS
The following schedule is intended as a general guide to maintenance and lubrication. Bear in mind that such factors as
weather, terrain, geographical location, and individual usage will alter the required maintenance and lubrication intervals. If
you are a doubt as to what intervals to follow in maintaining and lubricating your machine, consult your Yamaha dealer.
ItemAfter
break-inEvery
race
Every third
(or
500 km)Every fifth
(or
1,000 km)As
requiredRemarks
ENGINE OIL
Replace
Inspect
VALVES
Check the valve clearances The engine must be cold.
Check the valve seats and
valve stems for wear. Inspect
Replace
VALVE SPRINGS
InspectCheck the free length and
the tilt.
Replace
VALVE LIFTERS
InspectCheck for scratches and
wear.
Replace
CAMSHAFTSInspect the camshaft
surface.
Inspect the decompression
system. Inspect
Replace
TIMING CHAIN SPROCKETS, TIMING
CHAIN
InspectCheck for wear on the teeth
and for damage.
Replace
PISTON
InspectInspect crack
Inspect carbon deposits and
eliminate them. Clean
Replace
PISTON RING
InspectCheck ring end gap
Replace
PISTON PIN
Inspect
Replace
CYLINDER HEADInspect carbon deposits and
eliminate them.
Change gasket Inspect and clean
CYLINDER
Inspect and clean Inspect score marks
Inspect wear
Replace
CLUTCH
Inspect and adjust Inspect housing, friction
plate, clutch plate and spring
Replace
TRANSMISSION
Inspect
Replace bearing
SHIFT FORK, SHIFT CAM, GUIDE BAR
InspectInspect wear

3 - 16
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.3-21 ~ 29
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the
fuel line for leakage.P.1-35
Engine oilCheck that the oil level is correct. Check the crankcase and
frame oil line for leakage.P.3-39 ~ 47
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-29 ~ 31
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-31 ~ 33
Brakes Check the play of front brake and effect of front and rear brake. P.3-65 ~ 77
Drive chainCheck drive chain slack and alignment. Check that the drive
chain is lubricated properly.P.3-79 ~ 83
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-99 ~ 101
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-101 ~ 103
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage. P.3-83 ~ 97
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.4-7 ~ 11
Rear wheel sprocket Check that the rear wheel sprocket tightening bolt is not loose. P.3-77
Lubrication Check for smooth operation. Lubricate if necessary. P.3-105
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-45
Lead connectorsCheck that the AC magneto, CDI unit, and ignition coil are
connected tightly.P.1-9
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 ~ 42