light YAMAHA WR 250F 2008 Owners Manual

HOW TO READ DESCRIPTIONS
To help identify parts and clarify pro-
cedure steps, there are exploded dia-
grams at the start of each removal
and disassembly section.
1. An easy-to-see exploded diagram "1" is provided for removal and
disassembly jobs. 2. Numbers "2" are given in the or-
der of the jobs in the exploded di-
agram. A number that is enclosed
by a circle indicates a disassem-
bly step.
3. An explanation of jobs and notes is presented in an easy-to-read
way by the use of symbol marks
"3". The meanings of the symbol
marks are given on the next page. 4. A job instruction chart "4" accom-
panies the exploded diagram,
providing the order of jobs, names
of parts, notes in jobs, etc.
5. For jobs requiring more informa- tion, the step-by-step format sup-
plements "5" are given in addition
to the exploded diagram and job
instruction chart.
ILLUSTRATED SYMBO LS (Refer to
the illustration) Illustrated symbols "1" to "7" are used
to identify the specifications appear-
ing in the text.
1. With engine mounted
2. Filling fluid
3. Lubricant
4. Special tool
5. Tightening
6. Specified value, Service limit
7. Resistance (
Ω), Voltage (V),
Electric current (A)
Illustrated symbols "8" to "13" in the
exploded diagrams indicate grade of
lubricant and location of lubrication
point.
8. Apply engine oil
9. Apply molybdenum disulfide oil
10. Apply brake fluid
11. Apply lightweight lithium-soap base grease
12. Apply molybdenum disulfide
grease 13. Apply silicone grease
Illustrated symbols "14" to "15" in the
exploded diagrams indicate where to
apply a locking agent and where to in-
stall new parts.
14. Apply locking agent (LOC-
TITE
®)
15. Use new one
1
2 3
4 5

CONTENTS
CHAPTER 1GENERAL
INFORMATION
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
MULTI-FUNCTION
DISPLAY .......................... 1-9
STARTING AND
BREAK-IN ...................... 1-14
TORQUE-CHECK
POINTS........................... 1-16
CLEANING AND
STORAGE ...................... 1-17
CHAPTER 2
SPECIFICATIONS
GENERAL
SPECIFICATIONS ............ 2-1
MAINTENANCE
SPECIFICATIONS ............ 2-3
TIGHTENING
TORQUES ...................... 2-11
LUBRICATION
DIAGRAMS .................... 2-18
CABLE ROUTING
DIAGRAM ....................... 2-21
CHAPTER 3 REGULAR
INSPECTION AND ADJUSTMENTS
MAINTENANCE
INTERVALS ...................... 3-1
PRE-OPERATION
INSPECTION AND
MAINTENANCE................ 3-5
ENGINE ............................ 3-6
CHASSIS ........................ 3-17
ELECTRICAL ................. 3-27
CHAPTER 4 TUNING
ENGINE ............................ 4-1
CHASSIS .......................... 4-5
CHAPTER 5ENGINE
RADIATOR ....................... 5-1
CARBURETOR................. 5-4
AIR INDICTOIN
SYSTEM ......................... 5-12
CAMSHAFTS.................. 5-14
CYLINDER HEAD........... 5-19
VALVES AND VALVE
SPRINGS ........................ 5-21
CYLINDER AND
PISTON ........................... 5-25
CLUTCH ......................... 5-29
OIL FILTER ELEMENT
AND WATER PUMP ....... 5-34
BALANCER .................... 5-38
OIL PUMP ....................... 5-40
KICK SHAFT AND
SHIFT SHAFT ................. 5-43
AC MAGNETO AND
STARTER CLUTCH ....... 5-48
ENGINE REMOVAL ....... 5-53 CRANKCASE AND
CRANKSHAFT ...............5-57
TRANSMISSION, SHIFT
CAM AND SHIFT FORK .5-63
CHAPTER 6
CHASSIS
FRONT WHEEL AND
REAR WHEEL ..................6-1
FRONT BRAKE AND
REAR BRAKE ..................6-6
FRONT FORK .................6-16
HANDLEBAR..................6-23
STEERING ......................6-27
SWINGARM ....................6-31
REAR SHOCK
ABSORBER ....................6-36
CHAPTER 7
ELECTRICAL
ELECTRICAL
COMPONENTS AND
WIRING DIAGRAM ...........7-1
IGNITION SYSTEM...........7-3
ELECTRIC STARTING
SYSTEM............................7-5
CHARGING SYSTEM .....7-13
THROTTLE POSITION
SENSOR SYSTEM .........7-15
LIGHTING SYSTEM .......7-18
SIGNALING SYSTEM.....7-20

1-1
DESCRIPTION
GENERAL INFORMATION
DESCRIPTION
• The machine you have purchased may differ slightly from those shown in the following.
• Designs and specifications are subject to change without notice.
1. Clutch lever
2. Hot starter lever
3. Engine stop switch
4. Multi-function display
5. Main switch
6. Start switch
7. Front brake lever
8. Throttle grip
9. Radiator cap
10. Fuel tank cap
11. Taillight
12. Kickstarter crank
13. Fuel tank 14. Headlight
15. Radiator
16. Coolant drain bolt
17. Rear brake pedal
18. Valve joint
19. Fuel cock
20. Cold starter knob
21. Air cleaner
22. Catch tank
23. Drive chain
24. Oil level check window
25. Shift pedal
26. Front fork
1

1-3
CHECKING OF CONNECTION
ALL REPLACEMENT PARTS
1. We recommend to use Yamaha genuine parts for all replace-
ments. Use oil and/or grease rec-
ommended by Yamaha for
assembly and adjustment.
GASKETS, OIL SEALS AND O-
RINGS
1. All gaskets, oil seals, and O-rings should be replaced when an en-
gine is overhauled. All gasket sur-
faces, oil seal lips, and O-rings
must be cleaned.
2. Properly oil all mating parts and bearings during reassembly. Ap-
ply grease to the oil seal lips.
LOCK WASHERS/PLATES AND
COTTER PINS
1. All lock washers/plates "1" and cotter pins must be replaced
when they are removed. Lock
tab(s) should be bent along the
bolt or nut flat(s) after the bolt or
nut has been properly tightened.
BEARINGS AND OIL SEALS
1. Install the bearing(s) "1" and oil seal(s) "2" with their manufactur-
er's marks or numbers facing out-
ward. (In other words, the
stamped letters must be on the
side exposed to view.) When in-
stalling oil seal(s), apply a light
coating of lightweight lithium base
grease to the seal lip(s). Oil the
bearings liberally when installing.
Do not use compressed air to spin
the bearings dry. This causes dam-
age to the bearing surfaces.
CIRCLIPS
1. All circlips should be inspected carefully before reassembly. Al-
ways replace piston pin clips after
one use. Replace distorted cir-
clips. When installing a circlip "1",
make sure that the sharp-edged
corner "2" is positioned opposite
to the thrust "3" it receives. See
the sectional view.
CHECKING OF
CONNECTION
Dealing with stains, rust, moisture,
etc. on the connector.
1. Disconnect:• Connector
2. Dry each terminal with an air blower.
3. Connect and disconnect the con- nector two or three times.
4. Pull the lead to check that it will not come off.
5. If the terminal comes off, bend up the pin "1" and reinsert the termi-
nal into the connector.
6. Connect: • Connector
The two connectors "click" together.
7. Check for continuity with a tester.
• If there in no continuity, clean the terminals.
• Be sure to perform the steps 1 to 7 listed above when checking the
wire harness.
• For a field remedy, use a contact re- vitalizer available on the market.
• Use the tester on the connector as
shown.

1-5
SPECIAL TOOLS
Steering nut wrench
YU-33975, 90890-01403 This tool is used when tighten the
steering ring nut to specification.
Damper rod holder
YM-01494, 90890-01494 Use this tool to remove and install
the damper rod.
Fork seal driver
YM-A0948, 90890-01502 This tool is used when install the fork
oil seal.
Sheave holder
YS-1880-A, 90890-01701 This tool is used for when loosening
or tightening the flywheel magneto
securing nut.
Pocket tester
YU-3112-C, 90890-03112 Use this tool to inspect the coil resis-
tance, output voltage and amper-
age.
Timing light
YM-33277-A, 90890-03141 This tool is necessary for checking
ignition timing.
Tool name/Part number How to use Illustration

1-8
CONTROL FUNCTIONS
CONTROL FUNCTIONS
MAIN SWITCH
Functions of the respective switch po-
sitions are as follows:
ON:
The engine can be started only at this
position.
OFF:
All electrical circuits are switched off.
Main switch indicator light
The main switch "1" is equipped with
an indicator light "2" to avoid forget-
ting to turn it off. This light functions
as follows.
• It lights up with the main switch "ON".
• It goes out when the engine in-
creases its speed after being start-
ed.
• It lights up again when the engine is
stopped.
If the indicator light will not light up
with the main switch "ON", it shows a
lack of the battery voltage. Recharge
the battery.
ENGINE STOP SWITCH
The engine stop switch "1" is located
on the left handlebar. Continue push-
ing the engine stop switch till the en-
gine comes to a stop.
START SWITCH
The start switch "1" is located on the
right handlebar. Push this switch to
crank the engine with the starter. CLUTCH LEVER
The clutch lever "1" is located on the
left handlebar; it disengages or en-
gages the clutch. Pull the clutch lever
to the handlebar to disengage the
clutch, and release the lever to en-
gage the clutch. The lever should be
pulled rapidly and released slowly for
smooth starts.
SHIFT PEDAL
The gear ratios of the constant-mesh
5 speed transmission are ideally
spaced. The gears can be shifted by
using the shift pedal "1" on the left
side of the engine.
KICKSTARTER CRANK
Rotate the kickstarter crank "1" away
from the engine. Push the starter
down lightly with your foot until the
gears engage, then kick smoothly
and forcefully to start the engine. This
model has a primary kickstarter crank
so the engine can be started in any
gear if the clutch is disengaged. In
normal practices, however, shift to
neutral before starting.
THROTTLE GRIP
The throttle grip "1" is located on the
right handlebar; it accelerates or de-
celerates the engine. For accelera-
tion, turn the grip
toward you; for
deceleration, turn it away from you. FRONT BRAKE LEVER
The front brake lever "1" is located on
the right handlebar. Pull it toward the
handlebar to activate the front brake.
REAR BRAKE PEDAL
The rear brake pedal "1" is located on
the right side of the machine. Press
down on the brake pedal to activate
the rear brake.
FUEL COCK
The fuel cock supplies fuel from the
tank to carburetor and also filters the
fuel. The fuel cock has the three posi-
tions:
OFF:
With the lever in this position, fuel will
not flow. Always return the lever to
this position when the engine is not
running.
ON:
With the lever in this position, fuel
flows to the carburetor. Normal riding
is done with the lever in this position.
RES:
With the lever in this position fuel
flows to the carburetor from the re-
serve section of the fuel tank after the
main supply of the fuel has been de-
pleted. Normal riding is possible with
the lever is in this position, but it is
recommended to add fuel as soon as
possible.

1-10
MULTI-FUNCTION DISPLAY
To reset the digits, select the tripme-
ter involved and push the "RST" but-
ton for 2 seconds or more.
CHANGEOVER TO BASIC MODE/
RACE MODE
• Measurement using the timer func-tion can be made in RACE MODE.
• Indicator will light up as an identifier that shows RACE MODE
has been selected.
• RACE MODE cannot display the functions as in BASIC MODE.
• Changeover to RACE MODE forc- es the digits for tripmeter A (TRIP
A) in BASIC MODE to be reset.
Changeover from BASIC MODE to
RACE MODE
1. Push the "SLCT1" button and "SLCT2" button for 2 seconds or
more at the same time to change
over to RACE MODE.
Changeover to RACE MODE will put
manual start measurement on stand-
by causing and to flash. (For
manual start, refer to "Putting mea-
surement on standby" in "RACE
MODE".)
Returning to BASIC MODE from
RACE MODE
It is possible to return to BASIC
MODE with timer measurement at a
stop.
1. Check that the timer is not in op- eration. If the timer is in operation,
stop the timer by pushing the
"SLCT1" button and "SLCT2" but-
ton at the same time.
2. Push the "SLCT1" button and "SLCT2" button for 2 seconds or
more at the same time to change
over to BASIC MODE.
RACE MODE
Putting measurement on standby
Starting measurement consists of the
following two starts, either of which
can be selected.
• Manual start
Starting measurement by the rider
himself operating the button. (A long
push on the "SLCT2" button will put
measurement on standby.)
• Auto start
Starting timer measurement automat-
ically on detection of the movement of
the machine. (A long push on the
"SLCT1" button will put measurement
on standby.)
Manual start
Initial setting at changeover to RACE
MODE will remain for manual start.
1. Check that changeover to RACE MODE has been made. (Refer to
"Changeover from BASIC MODE
to RACE MODE".)
When the machine is made ready for
a run by manual start, and will
start flashing.
2. Start timer measurement by
pushing the "RST" button.
3. When stopping timer measure- ment, pushing the "SLCT1" but-
ton and "SLCT2" button at the
same time.
If the machine is run while timer mea-
surement is not made, no change will
occur to the digit in tripmeter A (TRIP
A).
4. To resume the measurement,
again push the "SLCT1" button
and "SLCT2" button at the same
time.
Auto start
1. Check that changeover has been made to RACE MODE. (Refer to
"Changeover from BASIC MODE
to RACE MODE".)
2. Make the machine ready for a run
by pushing the "SLCT1" button for
2 seconds or more.
When the measurement is made
ready for a run by auto start, and will start flashing. Timer display
will turn on scrolling from left to right.
3. Run the machine and start timer measurement.
4. To stop timer measurement,
pushing the "SLCT1" button and
"SLCT2" button at the same time.

1-17
CLEANING AND STORAGE
CLEANING AND STORAGE
CLEANING
Frequent cleaning of your machine
will enhance its appearance, maintain
good overall performance, and ex-
tend the life of many components.
1. Before washing the machine, block off the end of the exhaust
pipe to prevent water from enter-
ing. A plastic bag secured with a
rubber band may be used for this
purpose.
2. If the engine is excessively greasy, apply some degreaser to
it with a paint brush. Do not apply
degreaser to the chain, sprockets,
or wheel axles.
3. Rinse the dirt and degreaser off with a garden hose; use only
enough pressure to do the job.
Excessive hose pressure may
cause water seepage and contami-
nation of wheel bearings, front
forks, brakes and transmission
seals. Many expensive repair bills
have resulted from improper high
pressure detergent applications
such as those available in coin-op-
erated car washers.
4. After the majority of the dirt has been hosed off, wash all surfaces
with warm water and a mild deter-
gent. Use an old toothbrush to
clean hard-to-reach places.
5. Rinse the machine off immediate- ly with clean water, and dry all
surfaces with a soft towel or cloth.
6. Immediately after washing, re- move excess water from the
chain with a paper towel and lubri-
cate the chain to prevent rust.
7. Clean the seat with a vinyl uphol- stery cleaner to keep the cover
pliable and glossy.
8. Automotive wax may be applied to all painted or chromed surfac-
es. Avoid combination cleaner-
waxes, as they may contain abra-
sives.
9. After completing the above, start the engine and allow it to idle for
several minutes. STORAGE
If your machine is to be stored for 60
days or more, some preventive mea-
sures must be taken to avoid deterio-
ration. After cleaning the machine
thoroughly, prepare it for storage as
follows:
1. Drain the fuel tank, fuel lines, and
the carburetor float bowl.
2. Remove the spark plug, pour a ta-
blespoon of SAE 10W-30 motor
oil in the spark plug hole, and re-
install the plug. With the engine
stop switch pushed in, kick the en-
gine over several times to coat the
cylinder walls with oil.
3. Remove the drive chain, clean it thoroughly with solvent, and lubri-
cate it. Reinstall the chain or store
it in a plastic bag tied to the frame.
4. Lubricate all control cables.
5. Block the frame up to raise the
wheels off the ground.
6. Tie a plastic bag over the exhaust pipe outlet to prevent moisture
from entering.
7. If the machine is to be stored in a humid or salt-air environment,
coat all exposed metal surfaces
with a film of light oil. Do not apply
oil to rubber parts or the seat cov-
er.
Make any necessary repairs before
the machine is stored.

2-3
MAINTENANCE SPECIFICATIONS
MAINTENANCE SPECIFICATIONS
ENGINEBrake:
Front brake type Single disc brake
Operation Right hand operation
Rear brake type Single disc brake
Operation Right foot operation
Suspension: Front suspension Telescopic fork
Rear suspension Swingarm (link type monocross suspension)
Shock absorber: Front shock absorber Coil spring/oil damper
Rear shock absorber Coil spring/gas, oil damper
Wheel travel: Front wheel travel 300 mm (11.8 in)
Rear wheel travel 310 mm (12.2 in)
Electrical: Ignition system CDI
Generator system AC magneto
Battery type YTZ7S (F)
Battery voltage/capacity 12V/6 AH
Specific gravity 1.310
Headlight type: Quartz bulb (halogen)
Bulb wattage × quantity: Headlight 12 V 35/36.5 W × 1
Taillight 12 V 1.6/0.3 W × 1
ItemStandardLimit
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 21.959–21.972 mm (0.8645–0.8650 in) ----
Shaft-to-cap clearance 0.028–0.062 mm (0.0011–0.0024 in) 0.08 mm (0.003
in)

2-11
TIGHTENING TORQUES
TIGHTENING TORQUES
ENGINE
△- marked portion shall be checked for torque ti ghtening after break-in or before each race.
Normal output 14 V/120 W at 5,000 r/min----
Charging coil resistance (color) 0.288–0.432 Ω at 20 °C (68 °F) (White–
Ground) ----
Lighting coil resistance (color) 0.224–0.336 Ω at 20 °C (68 °F) (Yellow–
Ground) ----
Rectifier/regulator: Regulator type Semiconductor short circuit----
Model/manufacture SH770AA/SHINDENGEN----
Regulated voltage (AC) 12.5–13.5 V----
Regulated voltage (DC) 14.0–15.0 V----
Rectifier capacity (AC) 12 A----
Rectifier capacity (DC) 8 A----
Electric starting system: Type Constant mesh----
Starter motor: Model/manufacturer 5UM01/YAMAHA----
Operation voltage 12 V----
Output 0.35 kW----
Armature coil resistance 0.0189–0.0231 Ω at 20 °C (68 °F) ----
Brush overall length 7 mm (0.28 in)3.5 mm (0.14
in)
Brush quantity 2 pcs.----
Spring force 3.92–5.88 N (400–600 g, 14.1–21.2 oz) ----
Commutator diameter 17.6 mm (0.69 in)16.6 mm (0.65
in)
Mica undercut (depth) 1.5 mm (0.06 in) ----
Starter relay: Model/manufacturer 2768090-A/JIDECO----
Amperage rating 180 A----
Coil winding resistance 4.2–4.6 Ω at 20 °C (68 °F) ----
Starting circui t cut-off relay:
Model/manufacturer ACM33221 M38/MATSUSHITA ----
Coil winding resistance 75.69–92.51 Ω at 20 °C (68 °F) ----
Fuse (amperage×quantity): Main fuse 10 A × 1----
Reserve fuse 10 A × 1----
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