2010 YAMAHA YZ250F engine

2-13
TIGHTENING TORQUES
△Front brake disc M6 × 1.0 6 12 1.2 8.7
△ Rear brake disc M6 × 1.0 6 14 1.4 10
△ Footrest bracket and frame M10 × 1.25 4 55 5.5 40
△ Brake pedal M8 × 1.25 1 26 2.6 19
△ Rear brake master cylinder M6 × 1.0 2 10 1.0 7.2
Rear brake master cylinder cap M4 × 0.7 2 2 0.2 1.4
△ Rear brake hose union bolt M10 × 1.25 2 30 3.0 22
△ Rear wheel axle and axle nut M22 × 1.5 1 135 13.5 98
△ Nipple (spoke) —72 3 0.3 2.2
△ Rear wheel sprocket M8 × 1.25 6 42 4.2 30
△ Rear brake disc cover M6 × 1.0 2 10 1.0 7.2
△ Rear brake caliper protector M6 × 1.0 2 7 0.7 5.1
Drive chain puller adjust bolt and locknut M8 × 1.25 2 21 2.1 15
Engine mounting:
△ Engine and engine bracket (front) M10 × 1.25 1 53 5.3 38
△ Engine and frame (lower) M10 × 1.25 1 53 5.3 38
△ Upper engine bracket and frame M8 × 1.25 4 34 3.4 25
△ Front engine bracket and frame M8 × 1.25 4 34 3.4 25
△ Engine and engine bracket (upper) M10 × 1.25 2 55 5.5 40
Lower engine guard M6 × 1.0 3 10 1.0 7.2
CDI unit bracket M6 × 1.0 2 7 0.7 5.1
Cable guide and frame M6 × 1.0 2 7 0.7 5.1
△ Pivot shaft and nut M16 × 1.5 1 85 8.5 61
△ Relay arm and swingarm M14 × 1.5 1 70 7.0 50
△ Relay arm and connecting rod M14 × 1.5 1 80 8.0 58
△ Connecting rod and frame M14 × 1.5 1 80 8.0 58
△ Rear shock absorber and frame M10 × 1.25 1 56 5.6 40
△ Rear shock absorber and relay arm M10 × 1.25 1 53 5.3 38
△ Rear frame (upper) M8 × 1.25 2 32 3.2 23
△ Rear frame (lower) M8 × 1.25 2 32 3.2 23
△ Swingarm and brake hose holder M5 × 0.8 4 3 0.3 2.2
Upper drive chain tensioner M8 × 1.25 1 16 1.6 11
Lower drive chain tensioner M8 × 1.25 1 16 1.6 11
Drive chain support M6 × 1.0 3 7 0.7 5.1
△ Seal guard and swingarm M5 × 0.8 4 6 0.6 4.3
△ Fuel tank M6 × 1.0 1 9 0.9 6.5
△ Fuel cock M6 × 1.0 2 4 0.4 2.9
Seat set bracket and fuel tank M6 × 1.0 1 7 0.7 5.1
Fuel tank bracket and fuel tank M6 × 1.0 2 7 0.7 5.1
Side cover set bracket and fuel tank M6 × 1.0 2 7 0.7 5.1
Fitting band set screw and fuel tank M6 × 1.0 1 7 0.7 5.1
△ Air scoop and fuel tank M6 × 1.0 2 7 0.7 5.1
△ Air scoop and radiator guard M6 × 1.0 4 7 0.7 5.1
Air scoop and frame M6 × 1.0 2 7 0.7 5.1
Part to be tightened
Thread size Q'tyTightening torque
Nm m•kg ft•lb

2-15
TIGHTENING TORQUES
GENERAL TORQUE
SPECIFICATIONS
This chart specifies torque for stan-
dard fasteners with standard I.S.O.
pitch threads. Torque specifications
for special components or assem-
blies are included in the applicable
sections of this book. To avoid war-
page, tighten multi-fastener assem-
blies in a crisscross fashion, in
progressive stages, until full torque is
reached. Unless otherwise specified,
torque specifications call for clean,
dry threads. Components should be
at room temperature.A. Distance between flats
B. Outside thread diameter
DEFINITION OF UNITS
A
(Nut) B
(Bolt
) TORQUE SPECIFI-
CATION
Nm m•kg ft•lb
10
mm 6 mm 6 0.6 4.3
12
mm 8 mm 15 1.5 11
14
mm 10
mm 30 3.0 22
17
mm 12
mm 55 5.5 40
19
mm 14
mm 85 8.5 61
22
mm 16
mm 130 13 94
Unit
Read Definition Measure
mm
millimeter 10-3 meterLength
cmcentimeter 10-2 meterLength
kgkilogram 103 gramWeight
NNewton 1 kg × m/sec2Force
NmNewton meter N × mTorque
m•kgMeter kilogram m × kg Torque
PaPascalN/m2Pressure
N/mmNewton per millimeter N/mm Spring rate
LLiter—Volume or capacity
cm3Cubic centimeter —Volume or capacity
r/minRevolution per minute —Engine speed

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

2-24
CABLE ROUTING DIAGRAM
1. Throttle cable
2. Clamp
3. Hot starter cable
4. Clutch cable
5. Engine stop switch lead
6. Cable guide
7. Brake hose
8. Hose guideA. Fasten the engine stop switch
lead to the handlebar.
B. Pass the clutch cable and hot starter cable through the cable
guide.
C. Pass the engine stop switch lead behind the CDI unit. D. Pass the brake hose in front of
the number plate.
E. Pass the throttle cables through the cable guide.
F. Pass the clutch cable and hot
starter cable through the cable
guide on the number plate.
G. Pass the engine stop switch
lead over the number plate
mounting location.
A
C B
C
B
A

3-1
MAINTENANCE INTERVALS
REGULAR INSPECTION AND ADJUSTMENTS
MAINTENANCE INTERVALS
• The following schedule is intended as a general guide to mainten ance 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 mainta ining and lubricating your machine, consult your Yamaha dealer
• Periodic inspection is essential in making full use of the ma chine performance. The service life of the parts varies sub-
stantially according to the environment in which the machine runs (e.g., rain, dirt, etc.). Therefore, earlier inspection is
required by reference to the list below.
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
ENGINE OIL Replace ●●
Inspect ●●
OIL FILTER ELEMENT, OIL
STRAINER Clean ●
VALVES Check the valve clearances ●● The engine must be cold.
Inspect ●Check the valve seats and valve
stems for wear.
Replace ●
VALVE SPRINGS Inspect ●Check the free length and the tilt.
Replace ●
VALVE LIFTERS Inspect ●Check for scratches and wear.
Replace ●
CAMSHAFTS Inspect the camshaft surface.
Inspect ●Inspect the decompression system.
Replace ●
TIMING CHAIN SPROCKETS,
TIMING CHAIN Inspect ●Check for wear on the teeth and for
damage.
Replace ●
PISTON Inspect ●●Inspect crack.
Clean ●Inspect carbon deposits and eliminate
them.
Replace ●It is recommended that the piston pin
and ring are also replaced at the same
time.
PISTON RING Inspect ●Check ring end gap.
Replace ●●
3

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