diagram YAMAHA YZ250F 2012 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 SYMBOLS (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 fluid11. 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
23
45

CONTENTS
CHAPTER 1























































































































































































































































































































































































































































































































































































































































































































































































GENERAL
INFORMATION
LOCATION OF
IMPORTANT LABELS ..... 1-1
DESCRIPTION ................. 1-5
CONSUMER
INFORMATION................. 1-6
INCLUDED PARTS .......... 1-6
IMPORTANT
INFORMATION................. 1-6
CHECKING OF
CONNECTION .................. 1-7
SPECIAL TOOLS ............. 1-8
CONTROL
FUNCTIONS ................... 1-12
STARTING AND
BREAK-IN ...................... 1-13
TORQUE-CHECK
POINTS........................... 1-15
CLEANING AND
STORAGE ...................... 1-16
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
INSPECTION AND
ADJUSTMENTS
MAINTENANCE
INTERVALS ...................... 3-1
PRE-OPERATION
INSPECTION AND
MAINTENANCE................ 3-5
ENGINE ............................ 3-6
CHASSIS ........................ 3-14
ELECTRICAL ................. 3-24
CHAPTER 4
ENGINE
SEAT, FUEL TANK AND
SIDE COVERS.................. 4-1
EXHAUST PIPE AND
SILENCER ........................ 4-3
RADIATOR ....................... 4-7
CARBURETOR................. 4-9
CAMSHAFTS.................. 4-16
CYLINDER HEAD........... 4-21
VALVES AND VALVE
SPRINGS ........................ 4-23
CYLINDER AND
PISTON ........................... 4-27
CLUTCH ......................... 4-31
OIL FILTER ELEMENT
AND WATER PUMP ....... 4-35
BALANCER .................... 4-40
OIL PUMP ....................... 4-42
KICK SHAFT AND
SHIFT SHAFT ................. 4-46
CDI MAGNETO............... 4-51
ENGINE REMOVAL ....... 4-53
CRANKCASE AND
CRANKSHAFT ............... 4-57
TRANSMISSION,
SHIFT CAM AND
SHIFT FORK................... 4-63
CHAPTER 5
CHASSIS
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 ....................5-31
REAR SHOCK
ABSORBER ....................5-36
CHAPTER 6
ELECTRICAL
ELECTRICAL
COMPONENTS AND
WIRING DIAGRAM ...........6-2
IGNITION SYSTEM...........6-3
THROTTLE POSITION
SENSOR SYSTEM ...........6-6
CHAPTER 7
TUNING
ENGINE.............................7-1
CHASSIS ..........................7-6

2-16
LUBRICATION DIAGRAMS
LUBRICATION DIAGRAMS
1. Oil filter element
2. Oil pump
3. Drive axle
4. Main axle
5. Intake camshaft
6. Exhaust camshaft
7. Oil tank
8. Oil delivery pipe
A. To oil tank

2-17
LUBRICATION DIAGRAMS
1. Crankshaft
2. Oil filter element
3. Oil tank
4. Oil hose
A. From oil pump

2-18
CABLE ROUTING DIAGRAM
CABLE ROUTING DIAGRAM
1. Fuel tank breather hose
2. Radiator hose 1
3. Cylinder head breather hose
4. Radiator hose 3
5. Clutch cable
6. Throttle position sensor lead
7. Hot starter cable
8. Fuel hose
9. Carburetor breather hose10. Carburetor overflow hose
11. Throttle position sensor lead
protector
12. Throttle position sensor coverA. Insert the end of the fuel tank
breather hose into the hole in
the steering stem.
B. Aligh the paint mark on the cylin-
der head breather hose with the
front end of the hose guide.
A
B
AC
B
C

2-19
CABLE ROUTING DIAGRAM
C. Pass the cylinder head breather
hose on the outside of front en-
gine bracket.
D. Pass the cylinder head breather
hose between the radiator and
radiator hose 3.
E. Pass the fuel hose on the out-
side of throttle position sensor
lead.
F. Pass the carburetor breather
hoses and overflow hose so that
all there hoses do not contact
the rear shock absorber.
G. Insert the throttle position sen-
sor lead protector into the throt-
tle position sensor cover.

2-20
CABLE ROUTING DIAGRAM
1. Sub-wire harness
2. Hot starter cable
3. Oil hose
4. Neutral switch lead
5. Radiator hose 2
6. Clamp
7. Ignition coil lead
8. CDI magneto lead
9. Neutral switch lead coupler
10. CDI unit lead coupler11. Radiator breather hose
12. Hot starter cable protector
13. Rubber cap
14. Throttle position sensor lead
15. Cylinder head breather hose
16. Throttle position sensor lead
coupler
17. Tension pipe
18. Radiator mounting boss
19. Cylinder head breather hose20. Throttle position sensor tube
clamp
E K
E F GHH
F IJ A
AB
D
D CJ
C
G
B
K
E
M
M
H-H
K-K
E-E
D-D
M-M
F-F
A-A
I
L
L

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 lead
7. Bracket (CDI unit)
8. CDI unitA. 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.
CA
BB
A
C

2-23
CABLE ROUTING DIAGRAM
1. Brake master cylinder
2. Brake hose holder
3. Brake hoseA. Install the brake hose so that its
pipe portion directs as shown
and lightly touches the projec-
tion on the brake caliper.
B. Pass the brake hose into the
brake hose holders.C. If the brake hose contacts the
spring (rear shock absorber),
correct its twist.
D. Install the brake hose so that its
pipe portion directs as shown
and lightly touches the projec-
tion on the brake master cylin-
der.