2002 YAMAHA YZ250F engine

SPEC

2 - 2
GENERAL SPECIFICATIONS
Oil capacity:
Engine oil
Periodic oil change 1.5 L (1.32 Imp qt, 1.59 US qt)
With oil filter replacement 1.6 L (1.41 Imp qt, 1.69 US qt)
Total amount 1.7 L (1.50 Imp qt, 1.80 US qt)
Coolant capacity (including all routes): 0.9 L (0.79 Imp qt, 0.95 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 8.0 L (1.76 Imp gal, 2.11 US gal)
Carburetor:
Type FCR-MX37
Manufacturer KEIHIN
Spark plug:
Type/manufacturer CR8E/NGK
U24ESR-N/DENSO
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 48/13 (3.692)
Transmission type Constant mesh, 5-speed
Operation Left foot operation
Gear ratio: 1st 30/14 (2.143)
2nd 28/16 (1.750)
3rd 29/20 (1.450)
4th 27/22 (1.227)
5th 25/24 (1.042)
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, ZA, AUS, NZ
and F)
80/100-21 MT320 (For EUROPE except F)
Size (rear) 100/90-19 57M (For USA, CDN, ZA, AUS, NZ
and F)
100/90-19 MT320 (For EUROPE except F)
Tire pressure (front and rear) 100 kPa (1.0 kgf/cm
2

, 15 psi)

2

SPEC

2 - 4
MAINTENANCE SPECIFICATIONS
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

SPEC

2 - 8
MAINTENANCE SPECIFICATIONS
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 40.4 mm (1.59 in) 39.4 mm
(1.55 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: USA, CDN, ZA,
AUS, NZEUROPE
Type/manufacturer FCR-MX37/
KEIHIN
←
----
I. D. mark 5SG1 00 5SG2 10 ----
Main jet (M.J) #178
←
----
Main air jet (M.A.J) #200
←
----
Jet needle (J.N) OBEKP-4
←
----
Cutaway (C.A) 1.5
←
----
Pilot jet (P.J) #40
←
----
Pilot air jet (P.A.J) #100
←
----
Pilot outlet (P.O)ø0.9
←
----
Pilot screw (example) (P.S) 1-5/8 1-1/2 ----
Bypass (B.P)ø1.0
←
----
Valve seat size (V.S)ø3.8
←
----
Starter jet (G.S) #72
←
----
Leak jet (Acc.P) #100 #95 ----
Float height (F.H) 8 mm (0.31 in)
←
----
Engine idle speed 1,900 ~
2,100 r/min
←
----
Intake vacuum26.7 ~ 32.0 kPa
(200 ~ 240 mmHg,
7.87 ~ 9.45 inHg)
←
---- Item Standard Limit

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

SPEC
2 - 17
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 m•kg ft•lb
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
GENERAL TORQUE SPECIFICATIONS/
DEFINITION OF UNITS

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.

2 - 20
SPEC

1
Spark plug lead
2
Ignition coil
3
CDI unit
4
CDI unit band
5
Throttle cable (return)
6
Throttle cable (pull)
7
Cable guide
8
CDI unit lead
9
CDI unit stay
0
Radiator breather hose
A
Radiator hose 4
Å
Pass the CDI unit lead
between the radiator hose and
radiator mounting boss.
ı
Pass the throttle cables
through the cable guide.
Ç
Pass the throttle cables and
CDI unit lead through the cable
guide.
Î
Pass the throttle cables under
the radiator mounting boss.
‰
Insert the CDI unit band over
the CDI unit stay (frame) as far
as possible.
Ï
Pass the radiator breather
hose in front of the radiator
mounting rear boss and at the
left of the chassis. And then,
pass it between the radiator
hose 4 and down tube (frame)
and between the engine and
lower engine guard.
CABLE ROUTING DIAGRAM

2 - 22
SPECCABLE ROUTING DIAGRAM
1Throttle cable
2Clamp
3Decompression cable
4Clutch cable
5Brake hose
6Hose guide
7Engine stop switch leadÅFasten the engine stop switch lead to the handlebar with the plastic
band.
ıPass the brake hose in front of the number plate.