2008 YAMAHA YZ250F water pump

CONTENTS
CHAPTER 1
GENERAL INFOR-
MATION
DESCRIPTION ................. 1-1
MACHINE
IDENTIFICATION ............. 1-2
INCLUDED PARTS .......... 1-2
IMPORTANT
INFORMATION................. 1-2
CHECKING OF
CONNECTION .................. 1-3
SPECIAL TOOLS ............. 1-4
CONTROL FUNCTIONS .. 1-8
STARTING AND
BREAK-IN ........................ 1-8
TORQUE-CHECK
POINTS........................... 1-11
CLEANING AND
STORAGE ...................... 1-12
CHAPTER 2
SPECIFICATIONS
GENERAL
SPECIFICATIONS ............ 2-1
MAINTENANCE
SPECIFICATIONS ............ 2-3
TIGHTENING
TORQUES ...................... 2-10
LUBRICATION
DIAGRAMS .................... 2-16
CABLE ROUTING
DIAGRAM ....................... 2-18
CHAPTER 3
REGULAR INSPEC-
TION AND AD-JUSTMENTS
MAINTENANCE
INTERVALS ...................... 3-1
PRE-OPERATION
INSPECTION AND
MAINTENANCE................ 3-5
ENGINE ............................ 3-6
CHASSIS ........................ 3-14
ELECTRICAL ................. 3-23
CHAPTER 4 ENGINE
SEAT, FUEL TANK AND
SIDE COVERS.................. 4-1
EXHAUST PIPE AND
SILENCER ........................ 4-3
RADIATOR ....................... 4-5
CARBURETOR................. 4-7
CAMSHAFTS.................. 4-14
CYLINDER HEAD........... 4-19
VALVES AND VALVE
SPRINGS ........................ 4-21
CYLINDER AND
PISTON ........................... 4-25
CLUTCH ......................... 4-29
OIL FILTER ELEMENT
AND WATER PUMP ....... 4-34
BALANCER .................... 4-38
OIL PUMP ....................... 4-40
KICK SHAFT AND
SHIFT SHAFT ................. 4-44
CDI MAGNETO............... 4-49
ENGINE REMOVAL ....... 4-51
CRANKCASE AND
CRANKSHAFT ............... 4-55
TRANSMISSION, SHIFT
CAM AND SHIFT
FORK .............................. 4-61
CHAPTER 5CHASSIS
FRONT WHEEL AND
REAR WHEEL ..................5-1
FRONT BRAKE AND
REAR BRAKE ..................5-6
FRONT FORK ................. 5-16
HANDLEBAR..................5-24
STEERING ......................5-28
SWINGARM ....................5-32
REAR SHOCK
ABSORBER ....................5-37
CHAPTER 6
ELECTRICAL
ELECTRICAL
COMPONENTS AND
WIRING DIAGRAM ...........6-1
IGNITION SYSTEM...........6-2
THROTTLE POSITION
SENSOR SYSTEM ...........6-5
CHAPTER 7
TUNING
ENGINE.............................7-1
CHASSIS ..........................7-6

1-2
MACHINE IDENTIFICATION
MACHINE IDENTIFICATION
There are two significant reasons for
knowing the serial number of your
machine:
1. When ordering parts, you can give the number to your Yamaha
dealer for positive identification of
the model you own.
2. If your machine is stolen, the au-
thorities will need the number to
search for and identify your ma-
chine.
VEHICLE IDENTIFICATION
NUMBER
The vehicle identification number "1"
is stamped on the right of the steering
head pipe.
ENGINE SERIAL NUMBER
The engine serial number "1" is
stamped into the elevated part of the
right-side of the engine.
MODEL LABEL
The model label "1" is affixed to the
frame under the rider's seat. This in-
formation will be needed to order
spare parts.
INCLUDED PARTS
DETACHABLE SIDESTAND
This sidestand "1" is used to support
only the machine when standing or
transporting it.
• Never apply additional force to the sidestand.
• Remove this sidestand before
starting out.
VALVE JOINT
This valve joint "1" prevents fuel from
flowing out and is installed to the fuel
tank breather hose.
In this installation, make sure the
arrow faces the fuel tank and also
downward.
SPARK PLUG WRENCH
This spark plug wrench "1" is used to
remove and install the spark plug.
NIPPLE WRENCH
This nipple wrench "1" is used to
tighten the spoke.
JET NEEDLE PULL-UP TOOL
The jet needle pull-up tool "1" is used
to pull the jet needle out of the carbu-
retor.
IMPORTANT INFORMATION
PREPARATION FOR REMOVAL
AND DISASSEMBLY
1. Remove all dirt, mud, dust, and foreign material before removal
and disassembly.
• When washing the machine with high pressured water, cover the
parts follows.
Silencer exhaust port
Side cover air intake port
Water pump housing hole at the
bottom
Drain hole on the cylinder head
(right side)
2. Use proper tools and cleaning equipment. Refer to "SPECIAL
TOOLS" section.
3. When disassembling the ma- chine, 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 re-
placed.

2-8
MAINTENANCE SPECIFICATIONS
CHASSISHeight
240 mm (9.4 in)----
Thickness 22 mm (0.9 in)----
Radiator cap opening pressure 110 kPa (1.1 kg/cm
2, 15.6 psi)----
Radiator capacity (total) 0.58 L (0.51 Imp qt, 0.61 US qt)----
Water pump Type Single-suction centrifugal pump----
Item
StandardLimit
Item StandardLimit
Steering system: Steering bearing type Taper roller bearing----
Front suspension: Front fork travel 300 mm (11.8 in)----
Fork spring free length 454 mm (17.9 in)449 mm (17.7
in)
Spring rate, STD K = 4.4 N/mm (0.449 kg/mm, 25.1 lb/in)----
Optional spring Yes----
Oil capacity 521 cm
3 (18.3 lmp oz, 17.6 US oz)----
Oil grade Suspension oil "S1"----
Inner tube outer diameter 48 mm (1.89 in)----
Front fork top end 5 mm (0.20 in)----
Rear suspension: USA, CDN, AUS, NZ,
ZA EUROPE
Shock absorber travel 131.5 mm (5.18 in)
←----
Spring free length Approx.275 mm (10.83 in)
←----
Fitting length One I.D. mark 268 mm (10.55 in) 262 mm (10.31 in) ----
Two I.D. marks 274 mm (10.79 in) 268 mm (10.55 in) ----
Three I.D. marks 265.5 mm (10.45 in) 259.5 mm (10.22 in) ----
One I.D. mark 255.5–273.5 mm (10.06–10.77 in)
←----
Two I.D. marks 261.5–279.5 mm
(10.30–11.00 in)
←----
Three I.D. marks 253.0–271.0 mm (9.96–
10.67 in)
←----
Spring rate, STD K = 52.0 N/mm (5.30 kg/ mm, 296.8 lb/in)
←----
Optional spring Yes
←----
Enclosed gas pressure 1,000 kPa (10 kg/cm
2,
142 psi)←----
Swingarm: Swingarm free play limitEnd ---- 1.0 mm (0.04 in)
Wheel: Front wheel type Spoke wheel----

2-10
TIGHTENING TORQUES
TIGHTENING TORQUES
ENGINE
△- marked portion shall be checked for torque tightening after break-in or before each race.
Pickup coil resistance (color)248–372 Ωat 20 °C (68 °F) (White–Red) ----
CDI unit-model/manufacturer 5XC-L0/YAMAHA (For USA and CDN) ----
5XC-M0/YAMAHA (For EUROPE, AUS,
NZ and ZA) ----
Ignition coil: Model/manufacturer 5UL-10/DENSO----
Minimum spark gap 6 mm (0.24 in)----
Primary coil resistance 0.08–0.10
Ωat 20 °C (68 °F)----
Secondary coil resistance 4.6–6.8 k
Ωat 20 °C (68 °F)----
Item
StandardLimit
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 28 2.8 20
Cylinder head (stud bolt) M6 × 1.0 2 7 0.7 5.1
Cylinder head (stud bolt) M8 × 1.25 1 15 1.5 11
Cylinder head (bolt) M9 × 1.25 4 38 3.8 27
Cylinder head (nut) M6 × 1.0 2 10 1.0 7.2
Cylinder head cover M6 × 1.0 2 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
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 10 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 pipe M6 × 1.0 1 10 1.0 7.2
Oil pump cover M4 × 0.7 1 2 0.2 1.4
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 (crankcase) M6 × 1.0 2 10 1.0 7.2
Oil delivery pipe 1 (M10) M10 × 1.25 1 20 2.0 14
Oil delivery pipe 1 (M8) M8 × 1.25 2 18 1.8 13
Oil hose M6 × 1.0 2 8 0.8 5.8
△Oil hose clamp —1 2 0.2 1.4
Oil strainer (oil tank) M6 × 1.0 1 9 0.9 6.5

4-34
OIL FILTER ELEMENT AND WATER PUMP
OIL FILTER ELEMENT AND WATER PUMP
REMOVING THE OIL FILTER ELEMENT AND WATER PUMPOrder Part name Q'ty Remarks Drain the engine oil. Refer to "CHANGING THE ENGINE OIL"
section in the CHAPTER 3.
Drain the coolant. Refer to "CHANGING THE COOLANT" sec-
tion 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
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 section.

4-35
OIL FILTER ELEMENT AND WATER PUMP
9 Washer1 Refer to removal section.
10 Impeller shaft 1 Refer to removal section.
11 Oil seal 2 Refer to removal section.
12 Bearing 1 Refer to removal section.
Order
Part name Q'tyRemarks

4-36
OIL FILTER ELEMENT AND WATER PUMP
REMOVING THE IMPELLER
SHAFT
1. Remove:•Impeller "1"
• Washer "2"
• Impeller shaft "3"
Hold the impeller shaft on its width
across the flats "a" with spanners,
etc. and remove the impeller.
REMOVING THE OIL SEAL
It is not necessary to disassemble the
water pump, unless there is an abnor-
mality such as excessive change in
coolant level, discoloration of coolant,
or milky transmission oil.
1. Remove:
• Bearing "1"
2. Remove: •Oil seal "1"
CHECKING THE OIL DELIVERY
PIPE
1. Inspect: • Oil delivery pipe "1"Bend/damage
→Replace.
Clogged
→Blow. CHECKING THE IMPELLER SHAFT
1. Inspect:
• Impeller shaft "1"Bend/wear/damage
→Replace.
Fur deposits
→Clean.
CHECKING THE IMPELLER SHAFT
GEAR
1. Inspect: • Gear teeth "a"Wear/damage
→Replace.
CHECKING THE BEARING
1. Inspect: • BearingRotate inner race with a finger.
Rough spot/seizure
→Replace.
CHECKING THE OIL SEAL
1. Inspect: • Oil seal "1"
Wear/damage
→Replace.
INSTALLING THE OIL SEAL
1. Install: • Oil seal "1"
• Apply the lithium soap base grease on the oil seal lip.
• Install the oil seal with its manufac- ture's marks or numbers facing the
right crankcase cover "2".
2. Install:• Bearing "1"
Install the bearing by pressing its out-
er race parallel.
INSTALLING THE IMPELLER
SHAFT
1. Install:• Impeller shaft "1"
• Washer "2"
• Impeller "3"
• Take care so that the oil seal lip is
not damaged or the spring does not
slip off its position.
• When installing the impeller shaft, apply the lithium soap base grease
on the oil seal lip and impeller shaft.
And install the shaft while turning it.
• Hold the impeller shaft on its width across the flats "a" with spanners,
etc. and install the impeller.
Impeller: 14 Nm (1.4 m•kg, 10
ft•lb)

4-37
OIL FILTER ELEMENT AND WATER PUMP
INSTALLING THE RIGHT
CRANKCASE COVER
1. Install:• Dowel pin "1"
• O-ring "2"
•Collar "3"
•Gasket "4"
Apply the lithium soap base grease
on the O-ring.
2. Install:• Right crankcase cover "1"
• Bolt (right crankcase cover) "2"
• Apply the engine oil on the impeller
shaft end.
• Mesh the impeller shaft gear "3"
with primary drive gear "4".
• Tighten the bolts in stage, using a crisscross pattern.
INSTALLING THE KICKSTARTER
CRANK
1. Install:
• Kickstarter crank "1" •Washer
• Bolt (kickstarter crank)
Install so that there is a clearance "a"
of 5 mm (0.20 in) or more between
the kickstarter and frame and that the
kickstarter does not contact the
crankcase cover when it is pulled.
2. Install:
• Oil hose "1"
• Bolt (oil hose) "2"
3. Install: • Copper washer "1"
• Oil delivery pipe "2"
• Union bolt (M8) "3"
• Union bolt (M10) "4"
INSTALLING THE WATER PUMP
HOUSING
1. Install: • Dowel pin "1"
• O-ring "2"
Apply the lithium soap base grease
on the O-ring.
2. Install:• Water pump housing "1"
• Bolt (water pump housing) "2"
INSTALLING THE OIL FILTER
ELEMENT
1. Install: • Oil filter element "1"
• O-ring "2"
• Oil filter element cover "3"
• Bolt (oil filter element cover)
Apply the lithium soap base grease
on the O-ring.
Bolt (right crankcase
cover): 10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (kickstarter crank):
33 Nm (3.3 m•kg, 24
ft•lb)
Bolt (oil hose): 8 Nm (0.8 m•kg, 5.8
ft•lb)
Union bolt (M8): 18 Nm (1.8 m•kg, 13
ft•lb)
Union bolt (M10): 20 Nm (2.0 m•kg, 14
ft•lb)
Bolt (water pump hous-
ing):10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (oil filter element
cover): 10 Nm (1.0 m•kg, 7.2
ft•lb)