radiator YAMAHA YZ250F 2010 User Guide

2-21
CABLE ROUTING DIAGRAM
A. Pass the hot starter cable over the radiator mounting boss.
B. Pass the throttle position sensor lead under the hot starter cable.
C. Fasten the throttle position sen- sor lead and the hot starter ca-
ble.
D. Locate the clamp between the hot starter cable protector and
rubber cap.
E. Fasten the neutral switch lead below the oil hose. and pass the
neutral switch lead on the inside
of the oil hose.
F. Pass the neutral switch lead on the inside of the oil hose.
G. Fasten the neutral switch lead, CDI magneto lead, and radiator
breather hose onto the frame.
They should all be clamped
above the engine bracket to the
left of the downtube of the
frame. The clamp ends should
face backward and the rest out-
side of the frame.
H. Pass the clutch cable through the cable guide.
I. Pass the neutral switch lead and
CDI magneto lead behind the
frame.
J. Pass the hot starter cable on the
inside of the cylinder head
breather hose.
K. Fit the coupler projection into the
hole in the cover.
L. Fasten the sub-wire harness on the CDI unit bracket.
M. Fasten the sub-wire harness at the position-taped portion.
N. Pass each lead under the clamp. Locate the CDI magneto
lead on the outside of the igni-
tion coil lead. Locate the throttle
position sensor lead, neutral
switch lead, CDI magneto lead
and ignition coil lead so that they
do not lie one on another.
O. Fasten the sub-wire harness to
the CDI unit bracket with the
clamp ends located under the
bracket.
P. Fasten the neutral switch lead, throttle position sensor lead,
CDI magneto lead and ignition
coil lead. Fasten them around
the periphery of the recess be-
tween the tension pipe and radi-
ator mounting boss on the
frame.
Q. Locate the clamp ends within
the arrowed range. Assure that
the clamp end does not contact
the cylinder head breather hose. R. Pass the radiator breather hose
on the outside of the CDI mag-
neto lead and neutral switch
lead.
S. Fasten the throttle position sen- sor lead and hot starter cable.
Fasten them between the cylin-
der head breather hose and
throttle position sensor tube
clamp. Fasten the clamp with its
ends toward the right-side of the
frame and cut off the other end
with 3 to 5 clamp holes left in it.
T. Locate the radiator breather hose end above the down tube
and between the oil hose and
engine guard.
U. Fasten the neutral switch lead above the oil hose, and pass the
neutral switch lead on the inside
of the oil hose.

2-22
CABLE ROUTING DIAGRAM
1. Radiator hose 2
2. Radiator breather hose
3. Ignition coil
4. Throttle cable (pull)
5. Throttle cable (return)
6. Engine stop switch leadA. Put a cover over the ignition coil.
B. Pass the throttle cables through
the cable guide.
C. Pass the throttle cable over the radiator mounting boss. Cross
the throttle cable behind the ra-
diator.
D. Pass the throttle cables on the
outside of the ignition coil. E. Insert the engine stop switch
lead into the CDI unit band.
Align the coupler lower end with
the band lower end.
F. Fit the hole in the CDI unit band
over the CDI unit bracket.
C A
B B
A
C

3-3
MAINTENANCE INTERVALS
COOLING SYSTEMCheck coolant level and leakage ●●
Check radiator cap operation ●
Replace coolant ●Every two years
Inspect hoses ●
OUTSIDE NUTS AND BOLTS Retighten ●● Refer to "STARTING AND BREAK-
IN" section in the CHAPTER 1.
AIR FILTER Clean and lubricate ●● Use foam air-filter oil or equivalent oil.
Replace ●
OIL FILTER Replace ●●
OIL STRAINER Clean ●
ENGINE GUARD Replace ●Breakage
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, cali-
per bolts, master cylinder bolts
and union bolts ●●
Replace pads ●
Replace brake fluid ●Every one year
FRONT FORKS Inspect and adjust ●●
Replace oil ●● Suspension oil "S1"
Replace oil seal ●
FRONT FORK OIL SEAL AND
DUST SEAL Clean and lube ●● Lithium base grease
PROTECTOR GUIDE Replace ●
Item
After
break- in Every
race
(about 2.5
hours)
Every third
(about 7.5
hours) Every
fifth
(about 12.5
hours)
As re-
quired Remarks

3-5
PRE-OPERATION INSPECTION AND MAINTENANCE
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 RoutinePage
Coolant Check that coolant is filled up to the radiator cap. Check the cool-
ing system for leakage. P.3-6 – 7
Fuel Check that a fresh gasoline is filled in the fuel tank. Check the fuel
line for leakage. P.1-13
Engine oil Check that the oil level is correct. Check the crankcase and oil line
for leakage.
P.3-9 – 10
Gear shifter and clutch Check that gears can be shifted correctly in order and that the
clutch operates smoothly. P.3-7
Throttle grip/Housing Check that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary. P.3-7 – 8
Brakes Check the play of front brake and ef fect of front and rear brake. P.3-14 – 16
Drive chain Check drive chain slack and alignment. Check that the drive chain
is lubricated properly.
P.3-17 – 18
Wheels Check for excessive wear and ti
re pressure. Check for loose
spokes and have no excessive play. P.3-20 – 21
Steering Check that the handlebar can be turned smoothly and have no ex-
cessive play. P.3-21 – 22
Front forks and rear shock
absorber Check that they operate smooth
ly and there is no oil leakage.
P.3-18 – 20
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 pipe Check that the exhaust pipe is tightly mounted and has no cracks. P.4-3 – 4
Rear wheel sprocket Check that the rear whee l sprocket tightening bolt is not loose.P.3-17
Lubrication Check for smooth operation. Lubricate if necessary. P.3-23
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-15
Lead connectors Check that the CDI magneto, CDI
unit, and ignition coil are con-
nected tightly. P.1-7
Settings Is the machine set suitably for the
condition of the racing course
and weather or by taking into account the results of test runs be-
fore racing? Are inspection and maintenance completely done? P.7-1 – 10

3-6
ENGINE
ENGINE
CHECKING THE COOLANT LEVEL
Do not remove the radiator cap
"1", drain bolt and hoses when the
engine and radiator are hot. Scald-
ing 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 counter-
clockwise to the detent. This pro-
cedure allows any residual
pressure to escape. When the
hissing sound has stopped, press
down on the cap while turning
counterclockwise and remove it.
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 po-
sition.
2. Remove: • Radiator cap
3. Check: • Coolant level "a"Coolant level low →Add coolant.
1. Radiator
CHANGING THE COOLANT
Do not remove the radiator cap
when the engine is hot.
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 en- gine.
2. Remove: • Coolant drain bolt "1"
3. Remove: • Radiator capDrain the coolant completely.
4. Clean:
• Cooling systemThoroughly flush the cooling sys-
tem with clean tap water.
5. Install: • Copper washer
• Coolant drain bolt
6. Fill: • Radiator
•EngineTo specified level.
• Do not mix more than one type of
ethylene glycol antifreeze con-
taining corrosion inhibitors for
aluminum engine.
• Do not use water containing im- purities or oil.
Handling notes of coolant:
The coolant is harmful so it should be
handled with special care.
• 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.
7. Install:• Radiator cap
Start the engine and warm it up
for a several minutes.
8. Check:
• Coolant levelCoolant level low →Add coolant.
CHECKING THE RADIATOR CAP
1. Inspect: • Seal (radiator cap) "1"
• Valve and valve seat "2"Crack/damage →Replace.
Exist fur deposits "3" →Clean or
replace.
CHECKING THE RADIATOR CAP
OPENING PRESSURE
1. Attach: • Radiator cap tester "1" and adapt-er "2"
Apply water on the radiator cap seal.
Coolant drain bolt:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Recommended coolant: High quality ethylene
glycol anti-freeze con-
taining anti -corrosion
for aluminum engine
Coolant "1" and water
(soft water) "2" mixing ra-
tio: 50%/50%
Coolant capacity: 1.00 L (0.88 Imp qt, 1.06
US qt)
Radiator cap tester:
YU-24460-01/90890-
01325
Radiator cap tester
adapter: YU-33984/90890-01352

3-7
ENGINE
3. Radiator cap
2. Apply the specified pressure.
3. Inspect: • PressureImpossible to maintain the speci-
fied pressure for 10 seconds →
Replace.
CHECKING THE COOLING
SYSTEM
1. Inspect: • Coolant level
2. Attach: • Radiator cap tester "1" and adapt-
er "2"
3. Apply the specified pressure.
• Do not apply pressure more than specified pressure.
• Radiator should be filled fully.
4. Inspect: • PressureImpossible to maintain the speci-
fied pressure for 10 seconds →
Repair.
•Radiator "1"
• Radiator hose joint "2" Coolant leakage →Repair or re-
place.
• Radiator hose "3" Swelling →Replace. ADJUSTING THE CLUTCH LEVER
POSITION
1. Adjust:
• Clutch lever position
Clutch lever position adjustment
steps:
a. Loosen the locknuts "1".
b. Turn the adjusting bolt "2" until the clutch lever position "a" is in the
desiered position .
c. Tighten the locknuts.
2. Adjust: • Clutch cable free play
Refer to "ADJUSTING THE
CLUTCH CABLE FREE PLAY".
ADJUSTING THE CLUTCH CABLE
FREE PLAY
1. Check: • Clutch lever free play "a"Out of specification →Adjust.
2. Adjust: • Clutch lever free play
Clutch lever free play adjustment
steps:
a. Loosen the locknuts "1".
b. Turn the adjuster "2" until free play "a" is within the specified lim-
its.
c. Tighten the locknuts.
• Before adjustment, expose the ad- juster by moving the boot "3" and
cap "4" away.
• Make minute adjustment on the le- ver side using the adjuster "5".
• After adjustment, check proper op-
eration of clutch lever.
3. Install:•Cap "1"
• Boot "2"
Place the tip "a" of the cap in the boot.
ADJUSTING THE THROTTLE
CABLE FREE PLAY
1. Check:• Throttle grip free play "a"
Out of specification →Adjust.
Radiator cap opening
pressure:
110 kPa (1.1 kg/cm
2,
15.6 psi)
Radiator cap tester: YU-24460-01/90890-
01325
Radiator cap tester
adapter:
YU-33984/90890-01352
Standard pressure: 180 kPa (1.8 kg/cm
2,
25.6 psi)
Locknut: 5 Nm (0.5 m•kg, 3.6
ft•lb)
Clutch lever free play "a"
: 7–12 mm (0.28–0.47 in)
Locknut: 4 Nm (0.4 m•kg, 2.9
ft•lb)
Throttle grip free play
"a": 3–5 mm (0.12–0.20 in)

4-5
RADIATOR
RADIATOR
REMOVING THE RADIATOROrder Part name Q'ty Remarks Drain the coolant. Refer to "CHANGING
THE COOLANT" sec-
tion in the CHAPTER 3.
Seat and fuel tank Refer to "SEAT, FUEL TANK AND SIDE
COVERS" section.
1 Radiator guard 2
2 Radiator hose clamp 10 Only loosening.
3 Clutch cable holder 1
4 Radiator hose 1 1
5 Left radiator 1
6 Radiator hose 4 1
7Pipe 1
8 Radiator hose 5 1
9 Right radiator 1
10 Radiator hose 2 1
11 Radiator hose 3 1
12 Radiator breather hose 1
13 Radiator pipe 1 1
2
4 2
3
13
2
2
2
2
2 11
7
8
2
2
69
2 10
12
1
5
1
T R..20 Nm (2.0 m  kg, 14 ft  Ib)

4-6
RADIATOR
HANDLING NOTE
Do not remove the radiator cap
when the engine and radiator are
hot. Scalding hot fluid and steam
may be blown out under pressure,
which could cause serious injury.
When the engine has cooled, open
the radiator cap by the following
procedure:
Place a thick rag, like a towel, over
the radiator cap, slowly rotate the
cap counterclockwise to the de-
tent. This procedure allows any re-
sidual pressure to escape. When
the hissing sound has stopped,
press down on the cap while turn-
ing counterclockwise and remove
it.
CHECKING THE RADIATOR
1. Inspect:• Radiator core "1"
Obstruction →Blow out with com-
pressed air through rear of the ra-
diator.
Bent fin →Repair/replace.
INSTALLING THE RADIATOR
1. Install: • O-ring "1"
• Radiator pipe 1 "2"
• Bolt (radiator pipe) "3"
Apply the lithium soap base grease
on the O-ring.
2. Install:• Radiator breather hose "1"
• Radiator hose 2 "2"
• Radiator hose 4 "3"
• Pipe "4"
• Radiator hose 5 "5"
• Radiator hose 3 "6"To right radiator "7".
3. Install: • Right radiator "1"
• Bolt (right radiator) "2"
• Radiator hose 5 "3"
Refer to "CABLE ROUTING DIA-
GRAM" section in the CHAPTER
2.
4. Install: • Left radiator "1"
• Bolt (left radiator) "2"
• Radiator hose 1 "3"
Refer to "CABLE ROUTING DIA-
GRAM" section in the CHAPTER
2.
5. Tighten:
• Radiator hose clamp "4" 6. Install:
• Radiator guard "1"
First fit the inner hook portion "a" and
then the outer one "b" onto the radia-
tor.
Bolt (radiator pipe):
10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (right radiator):10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (left radiator): 10 Nm (1.0 m•kg, 7.2
ft•lb)
Radiator hose 1: 2 Nm (0.2 m•kg, 1.4
ft•lb)
Radiator hose clamp: 2 Nm (0.2 m•kg, 1.4
ft•lb)

4-19
CYLINDER HEAD
CYLINDER HEAD
REMOVING THE CYLINDER HEADOrder Part name Q'ty Remarks Seat and fuel tank Refer to "SEAT, FUEL TANK AND SIDE
COVERS" section.
Exhaust pipe and silencer Refer to "EXHAUST PIPE AND SILENCER"
section.
Radiator hose 1 Disconnect at cylinder head side.
Carburetor Refer to "CARBURETOR" section.
Camshaft Refer to "CAMSHAFTS" section.
Upper engine bracket Refer to "ENGINE REMOVAL" section.
1 Radiator pipe 1
2 Oil delivery pipe 1
3Nut 2
4 Bolt [L = 135 mm (5.31 in)] 2
5 Bolt [L = 145 mm (5.71 in)] 2
6 Cylinder head 1
7 Timing chain guard (exhaust side) 1

4-20
CYLINDER HEAD
CHECKING THE CYLINDER HEAD
1. Eliminate:• Carbon deposits (from the com-bustion chambers)
Use a rounded scraper.
Do not use a sharp instrument to
avoid damaging or scratching:
• Spark plug threads
• Valve seats
2. Inspect:• Cylinder head
Scratches/damage →Replace.
Replace the titanium valves with the
cylinder head.
Refer to "CHECKING THE
VALVE".
3. Measure:
• Cylinder head warpageOut of specification →Resurface.
Warpage measurement and resur-
facing steps:
a. Place a straightedge and a feeler
gauge across the cylinder head.
b. Use a feeler gauge to measure the warpage.
c. If the warpage is out of specifica- tion, resurface the cylinder head.
d. Place a 400–600 grit wet sandpa-
per on the surface plate, and re-
surface the head using a figure-
eight sanding pattern.
To ensure an even surface rotate the
cylinder head several times.
INSTALLING THE CYLINDER
HEAD
1. Install:• Dowel pin "1"
• Cylinder head gasket "2"
• Timing chain guide (exhaust side) "3"
• Cylinder head "4"
While pulling up the timing chain, in-
stall the timing chain guide (exhaust
side) and cylinder head.
2. Install: • Washer "1"
• Cable guide "2"
• Bolts [L = 145 mm (5.71 in)] "3"
• Bolts [L = 135 mm (5.31 in)] "4"
•Nuts "5"
• Apply the molybdenum disulfide
grease on the thread and contact
surface of the bolts.
• Follow the numerical order shown
in the illustration. Tighten the bolts
and nuts in two stages.
3. Install:• Copper washer "1"
• Oil delivery pipe "2"
• Union bolt (M8) "3"
• Union bolt (M10) "4"
First tighten the union bolts temporar-
ily. Then retighten them with the width
"a" across flats of the oil delivery pipe
held tight with a spanner.
4. Install:
• Radiator pipe "1"
• Bolt (radiator pipe) "2"
Cylinder head warpage:
Less than 0.05 mm
(0.002 in)
Bolts [L = 145 mm (5.71
in)]:38 Nm (3.8 m•kg, 27
ft•lb)
Bolts [L = 135 mm (5.31
in)]: 38 Nm (3.8 m•kg, 27
ft•lb)
Nuts: 10 Nm (1.0 m•kg, 7.2
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 (radiator pipe): 10 Nm (1.0 m•kg, 7.2
ft•lb)