2002 YAMAHA WR 250F water pump

CHAPTER 4
ENGINE
SEAT, FUEL TANK
AND SIDE COVERS
................................. 4-1
EXHAUST PIPE AND SILENCER
............ 4-2
RADIATOR
................................................ 4-4
CARBURETOR
......................................... 4-7
CAMSHAFTS
.......................................... 4-21
CYLINDER HEAD
................................... 4-30
VALVES AND VALVE SPRINGS
........... 4-34
CYLINDER AND PISTON
....................... 4-43
CLUTCH
.................................................. 4-50
OIL FILTER ELEMENT, WATER PUMP
AND RIGHT CRANKCASE COVER
...... 4-57
BALANCER
............................................ 4-64
OIL PUMP
............................................... 4-67
KICK SHAFT AND SHIFT SHAFT
.......... 4-72
CDI MAGNETO
....................................... 4-79
ENGINE REMOVAL
................................ 4-83
CRANKCASE AND CRANKSHAFT
....... 4-88
TRANSMISSION, SHIFT CAM
AND SHIFT FORK
.................................. 4-97
CHAPTER 5
CHASSIS
FRONT WHEEL AND REAR WHEEL
...... 5-1
FRONT BRAKE AND REAR BRAKE
..... 5-11
FRONT FORK
......................................... 5-28
HANDLEBAR
.......................................... 5-41
STEERING
.............................................. 5-47
SWINGARM
............................................ 5-53
REAR SHOCK ABSORBER
................... 5-60

1 - 3
GEN
INFO

IMPORTANT INFORMATION
EC130000
IMPORTANT INFORMATION
EC131010
PREPARATION FOR REMOVAL AND
DISASSEMBLY
1. Remove all dirt, mud, dust, and foreign
material before removal and disassem-
bly.
When washing the machine with high
pressured water, cover the parts follows.

Silencer end

Air filter intake hole

Water pump housing hole at the bottom

Carburetor accelerator pump
2. Use proper tools and cleaning equip-
ment. Refer to “SPECIAL TOOLS” sec-
tion.
3. When disassembling the machine, keep
mated parts together. They include
gears, cylinders, pistons, and other
mated parts that have been “mated”
through normal wear. Mated parts must
be reused as an assembly or replaced.
4. During the machine disassembly, clean
all parts and place them in trays in the
order of disassembly. This will speed up
assembly time and help assure that all
parts are correctly reinstalled.
5. Keep away from fire.

SPEC

2 - 9
MAINTENANCE SPECIFICATIONS
Lubrication system:
Oil filter type Wire mesh type ----
Oil pump type Trochoid type ----
Tip clearance 0.12 mm or less
(0.0047 in or less)0.20 mm
(0.008 in)
Side clearance 0.09 ~ 0.17 mm
(0.0035 ~ 0.0067 in)0.24 mm
(0.009 in)
Housing and rotor clearance 0.03 ~ 0.10 mm
(0.0012 ~ 0.0039 in)0.17 mm
(0.0067 in)
Cooling:
Radiator core size
Width 117.8 mm (4.6 in) ----
Height 220 mm (8.7 in) ----
Thickness 32 mm (1.26 in) ----
Radiator cap opening pressure110 kPa (1.1 kg/cm
2

, 15.6 psi)----
Radiator capacity (total) 0.6 L (0.53 lmp qt, 0.63 US qt) ----
Water pump
Type Single-suction centrifugal pump ----Item Standard Limit

SPEC

2 - 10
MAINTENANCE SPECIFICATIONS
Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Spark plug M10S
×
1.0 1 13 1.3 9.4
Camshaft cap M6
×
1.0 10 10 1.0 7.2
Cylinder head blind plug screw M12
×
1.0 1 37 3.7 27
Cylinder head (stud bolt) M6
×
1.0 2 7 0.7 5.1
(stud bolt) M8
×
1.25 1 15 1.5 11
(bolt) M9
×
1.25 4 38 3.8 27
(nut) M6
×
1.0 2 10 1.0 7.2
Cylinder head cover M6
×
1.0 2 10 1.0 7.2
Oil pressure check bolt M6
×
1.0 1 10 1.0 7.2
Cylinder M6
×
1.0 1 10 1.0 7.2
Balancer weight M6
×
1.0 2 10 1.0 7.2
Balancer shaft driven gear M14
×
1.0 1 50 5.0 36
Timing chain guide (intake side) M6
×
1.0 2 10 1.0 7.2
Decompression shaft M6
×
1.0 1 7 0.7 5.1
Decompression cable guide M6
×
1.0 1 10 1.0 7.2
Timing chain tensioner M6
×
1.0 2 10 1.0 7.2
Timing chain tensioner cap bolt M6
×
1.0 1 7 0.7 5.1
Impeller M8
×
1.25 1 14 1.4 10
Radiator hose clamp M6
×
1.0 8 2 0.2 1.4
Coolant drain bolt M6
×
1.0 1 10 1.0 7.2
Water pump housing M6
×
1.0 4 10 1.0 7.2
Radiator M6
×
1.0 6 10 1.0 7.2
Radiator guard M6
×
1.0 2 10 1.0 7.2
Radiator pipe M6
×
1.0 1 10 1.0 7.2
Oil pump cover M4
×
0.7 1 3 0.3 2.2
Oil pump M6
×
1.0 3 10 1.0 7.2
Oil filter element drain bolt M6
×
1.0 1 10 1.0 7.2
Oil filter element cover M6
×
1.0 2 10 1.0 7.2
Oil strainer M6
×
1.0 2 10 1.0 7.2
Oil delivery pipe 1 (M10) M10
×
1.25 1 20 2.0 14
(M8) M8
×
1.25 2 18 1.8 13
Oil delivery pipe 2 M6
×
1.0 1 10 1.0 7.2
Oil hose M6 × 1.0 3 10 1.0 7.2
Oil hose clamp—2 2 0.2 1.4
Oil strainer and frame M18 × 1.5 1 90 9.0 65
Carburetor joint clamp M4 × 0.7 2 3 0.3 2.2
Air filter joint clamp M6 × 1.0 1 3 0.3 2.2
Throttle cable cover M5 × 0.8 1 4 0.4 2.9
Air filter joint M5 × 0.8 2 5 0.5 3.6
Air filter joint and air filter case M5 × 0.8 5 1 0.1 0.7
Air filter element M6 × 1.0 1 2 0.2 1.4
Air filter case cover M6 × 1.0 4 4 0.4 2.9
Exhaust pipe (nut) M8 × 1.25 1 13 1.3 9.4
(bolt) M8 × 1.25 1 24 2.4 17
Exhaust pipe protector M6 × 1.0 3 10 1.0 7.2

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
*SPARK ARRESTER
Clean
(Every six
months)
●
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 race
or
500 km
(300 mi)Every
fifth race
or
1,000 km
(600 mi)
As re-
quiredRemarks


3

4 - 57
ENG

OIL FILTER ELEMENT, WATER PUMP AND RIGHT
CRANKCASE COVER
OIL FILTER ELEMENT, WATER PUMP AND RIGHT
CRANKCASE COVER
Extent of removal:
1
Oil filter element removal
2
Water pump removal
3
Right crankcase cover removal
Extent of removal Order Part name Q’ty Remarks
OIL FILTER ELEMENT, WATER
PUMP AND RIGHT CRANK-
CASE COVER REMOVAL
Preparation for removal Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Drain the coolant. Refer to “COOLANT REPLACEMENT”
section in the CHAPTER 3.
Radiator hose 3 Disconnect at water pump side.
Exhaust pipe Refer to “EXHAUST PIPE AND
SILENCER” section.
Brake pedal Refer to “ENGINE REMOVAL” section.
Right engine guard
1 Oil filter element cover 1
2 Oil filter element 1
13

4 - 58
ENG

OIL FILTER ELEMENT, WATER PUMP AND RIGHT
CRANKCASE COVER
Extent of removal Order Part name Q’ty Remarks
3 Water pump housing 1
4 Oil delivery pipe 1
5 Bolt (oil hose) 1
6 Kickstarter crank 1
7 Right crankcase cover 1
8 Impeller 1
Refer to “REMOVAL POINTS”. 9 Washer 1
10 Impeller shaft 1
11 Oil seal 2
12Bearing
1
3
2

4 - 59
ENG

OIL FILTER ELEMENT, WATER PUMP AND RIGHT
CRANKCASE COVER
REMOVAL POINTS
Impeller shaft
1. Remove:

Impeller
1


Washer
2


Impeller shaft
3

NOTE:

Hold the impeller shaft on its width across the
flats
a
with spanners, etc. and remove the
impeller.
EC4G3210
Oil seal
NOTE:

It is not necessary to disassemble the water
pump, unless there is an abnormality such as
excessive change in coolant level, discolora-
tion of coolant, or milky transmission oil.
1. Remove:

Bearing
1

2. Remove:

Oil seal
1

INSPECTION
Oil delivery pipe
1. Inspect:

Oil delivery pipe
1

Bend/damage
→
Replace.
Clogged
→
Blow.