engine YAMAHA WR 250F 2002 Owner's Guide

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SPECCABLE ROUTING DIAGRAM
1Throttle cable
2Light switch
3Light switch lead
4Clamp
5Decompression cable
6Clutch cable
7Hose guide
8Trip meter
9Brake hose
0Engine stop switch leadÅFasten the engine stop switch lead to the handlebar with the plastic
band.
ıPass the throttle cables between the upper bracket and trip meter.
ÇPass the light switch leads behind the engine stop switch lead, then
pass the headlight lead (of the light switch leads) in front of the head
pipe.
ÎInstall the trip meter cable so that its bent portion faces the chassis
rear.
‰Install the brake hose so that it contacts the master cylinder projec-
tion and that its bent portion faces downward.

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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 race
or
500 km
(300 mi)Every
fifth race
or
1,000 km
(600 mi)
As re-
quiredRemarks
ENGINE OIL
Replace
Inspect
●

●●

●
OIL FILTER ELEMENT, OIL STRAINER
Clean
●

VALVES
Check the valve clearances.
Inspect
Replace
●

●

●

●
The engine must be cold.
Check the valve seats
and valve stems for wear.
VALVE SPRINGS
Inspect
Replace
●

●
Check the free length and
the tilt.
VALVE LIFTERS
Inspect
Replace
●

●
Check for scratches and
wear.
CAMSHAFTS
Inspect
Replace
●

●
Inspect the camshaft sur-
face.
TIMING CHAIN SPROCKETS, TIMING
CHAIN
Inspect
Replace
●

●
Check for wear on the
teeth and for damage.
PISTON
Inspect
Clean
Replace
●

●

●

●
Inspect crack
Remove carbon
PISTON RING
Inspect
Replace
●

●

●
Check ring end gap
PISTON PIN
Inspect
Replace
●

●

CYLINDER HEAD
Inspect and clean
●
Remove carbon
Change gasket
CYLINDER
Inspect and clean
Replace
●

●
Inspect score marks
Inspect wear
CLUTCH
Inspect and adjust
Replace
●

●

●
Inspect housing, friction
plate, clutch plate and
spring
TRANSMISSION
Inspect
Replace bearing
●

●

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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 that the coolant level is correct in the coolant reservoir.
Check the cooling system for leakage.P.3-5 ~ 9
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the
fuel line for leakage.P.1-14
Engine oilCheck that the oil level is correct. Check the crankcase and
frame oil line for leakage.P.3-14 ~ 18
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-9
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-10 ~ 11
Brakes Check the play of front brake and effect of front and rear brake. P.3-26 ~ 32
Drive chainCheck drive chain slack and alignment. Check that the drive
chain is lubricated properly.P.3-33 ~ 35
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-43 ~ 44
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-44 ~ 45
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage. P.3-35 ~ 42
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.4-2
Rear wheel sprocket Check that the rear wheel sprocket tightening bolt is not loose. P.3-33
Lubrication Check for smooth operation. Lubricate if necessary. P.3-46
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-18
Lead connectorsCheck that the CDI magneto, CDI unit, and ignition coil are con-
nected tightly.P.1-6
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 ~ 23

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EC350000
ENGINE
EC351011
COOLANT LEVEL INSPECTION
WARNING
Do not remove the radiator cap 1, drain
bolt and hoses when the engine and radia-
tor are hot. Scalding hot fluid and steam
may be blown out under pressure, which
could cause serious injury.
When the engine has cooled, place a thick
towel over the radiator cap, slowly rotate
the cap counterclockwise to the detent.
This procedure allows any residual pres-
sure to escape. When the hissing sound
has stopped, press down on the cap while
turning counterclockwise and remove it.
CAUTION:
Hard water or salt water is harmful to the
engine parts. You may use distilled water, if
you can’t get soft water.
1. Place the machine on a level place, and
hold it in an upright position.
2. Inspect:
Coolant level
Coolant level should be between the
maximum a and minimum b marks.
Coolant level is below the “LOW” level
line → Add soft water (tap water) up to
the proper level.
3. Start the engine and let it warm up for
several minutes.
4. Turn off the engine and check the coolant
level again.
NOTE:
Before checking the coolant level, wait a few
minutes until the coolant settles.
LOWFULLCOOLANT
a
b
COOLANT REPLACEMENT
WARNING
Do not remove the radiator cap when the
engine is hot.
ENGINE/COOLANT LEVEL INSPECTION/
COOLANT REPLACEMENT

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COOLANT REPLACEMENT
CAUTION:
Take care so that coolant does not splash
on painted surfaces. If it splashes, wash it
away with water.
1. Place a container under the engine.
2. Remove:
Seat
Left side cover
Refer to ”SEAT FUEL TANK AND SIDE
COVERS” section in the CHAPTER 4.
3. Disconnect:
Coolant reservoir hose 1
Drain the coolant completely.
4. Connect:
Coolant reservoir hoseLOWFULLCOOLANT1
5. Remove:
Coolant drain bolt 1
6. Remove:
Radiator cap
Drain the coolant completely.
7. Clean:
Cooling system
Thoroughly flush the cooling system
with clean tap water.
8. Install:
Copper washer
Coolant drain bolt
9. Fill:
Radiator
Engine
To specified level.
Recommended coolant:
High quality ethylene glycol
anti-freeze containing
anti-corrosion for
aluminum engine
Coolant 1 and water
(soft water) 2 mixing ratio:
50%/50%
Coolant capacity:
1.3 L (1.14 Imp qt, 1.37 US qt)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

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RADIATOR CAP INSPECTION
CAUTION:
Do not mix more than one type of ethyl-
ene glycol antifreeze containing corro-
sion inhibitors for aluminum engine.
Do not use water containing impurities or oil.
10. Install:
Radiator cap
11. Fill:
Coolant reservoir
Midway a between maximum and min-
imum marks on the tank.
12. Install:
Coolant reservoir cap
13. Start the engine and let it warm up for
several minutes.
14. Turn off the engine and inspect the cool-
ant level.
Refer to “COOLANT LEVEL INSPEC-
TION” section.
NOTE:
Before checking the coolant level wait a few
minutes until the coolant settles.Handling notes of coolant:
The coolant is harmful so it should be han-
dled with special care.
WARNING
When coolant splashes to your eye.
Thoroughly wash your eye with water
and see your doctor.
When coolant splashes to your clothes.
Quickly wash it away with water and
then with soap.
When coolant is swallowed.
Quickly make him vomit and take him
to a doctor.
LOWFULLCOOLANTa
EC355000
RADIATOR CAP INSPECTION
1. Inspect:
Seal (radiator cap) 1
Valve and valve seat 2
Crack/damage → Replace.
Exist fur deposits 3 → Clean or
replace.

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THROTTLE CABLE ADJUSTMENT
THROTTLE CABLE ADJUSTMENT
1. Check:
Throttle grip free play a
Out of specification → Adjust.
Throttle grip free play a:
3 ~ 5 mm (0.12 ~ 0.20 in)
2. Adjust:
Throttle grip free play
Throttle grip free play adjustment steps:
Remove the throttle cable cap 1 and
throttle cable cover 2.
NOTE:
Before adjusting the throttle cable free
play, the engine idle speed should be
adjusted.
When the motorcycle is accelerating,
throttle cable #1 3 is pulled and throttle
cable #2 4 is pushed.
1st step:
Loosen the locknuts 5 on throttle cable
#2.
Adjust the free play by changing their
tightening position.
2nd step:
Loosen the locknuts 6 on throttle cable
#1.
Adjust the free play by changing their
tightening position.
Tighten the locknuts.
WARNING
After adjusting, turn the handlebar to
right and left and make sure that the
engine idling does not run faster.
Install the throttle cable cover and throttle
cable cap.
T R..
Throttle cable cover:
4 Nm (0.4 m • kg, 2.9 ft • lb)
2
1

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AIR FILTER CLEANING
2. Adjust:
Decompression lever free play
Adjustment steps:
Loosen the locknut 1.
Turn the adjuster 2 in or out until the
adjustment is suitable.
Tighten the locknut.
CAUTION:
After the adjustment, start the engine
and make sure that the engine does not
stop when the handlebar is turned fully
both ways. If the decompression cable is
too tense, the engine will stop by the
decompression system.
AIR FILTER CLEANING
NOTE:
Proper air filter maintenance is the biggest key
to preventing premature engine wear and
damage.
CAUTION:
Never run the engine without the air filter
element in place; this would allow dirt and
dust to enter the engine and cause rapid
wear and possible engine damage.
1. Remove:
Seat
2. Disconnect:
Taillight lead connectors 1
3. Remove:
Air filter case cover 2
4. Remove:
Fitting bolt 1
Washer 2
Air filter element 3
Air filter guide 4

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AIR FILTER CLEANING
5. Clean:
Air filter element
Clean them with solvent.
NOTE:
After cleaning, remove the remaining solvent
by squeezing the element.
CAUTION:
Do not twist the element when squeezing
the element.
Leaving too much of solvent in the ele-
ment may result in poor starting.
6. Inspect:
Air filter element
Damage → Replace.
7. Apply:
Foam-air-filter oil or engine oil to the ele-
ment.
NOTE:
Squeeze out the excess oil. Element should
be wet but not dripping.
8. Install:
Air filter guide 1
NOTE:
Align the projection a on air filter guide with
the hole b in air filter element.
9. Apply:
Lithium soap base grease
On the matching surface a on air filter
element.

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10. Install:
Air filter element 1
Washer
Fitting bolt
NOTE:
Align the projection a on filter guide with the
hole b in air filter case.
T R..2 Nm (0.2 m · kg, 1.4 ft · lb)
ENGINE OIL LEVEL INSPECTION
1. Start the engine, warm it up for several
minutes, and then turn off the engine and
wait for five minutes.
2. Place the machine on a level place and
hold it up on upright position by placing
the suitable stand under the engine.
3. Remove:
Oil tank cap 1
4. Inspect:
Oil level
Oil level should be between maximum
a and minimum b marks.
Oil level is low → Add oil to proper
level.
NOTE:
When inspecting the oil level, do not screw the
oil tank cap into the oil tank. Insert the gauge
lightly.
ENGINE OIL LEVEL INSPECTION