2009 YAMAHA YZ250F valve

CONTENTS
CHAPTER 1
GENERAL
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
STARTING AND
BREAK-IN ........................ 1-8
TORQUE-CHECK
POINTS........................... 1-11
CLEANING AND
STORAGE ...................... 1-12
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 ....................... 4-5
CARBURETOR................. 4-7
CAMSHAFTS.................. 4-14
CYLINDER HEAD........... 4-19
VALVES AND VALVE
SPRINGS ........................ 4-21
CYLINDER AND
PISTON ........................... 4-25
CLUTCH ......................... 4-29
OIL FILTER ELEMENT
AND WATER PUMP ....... 4-33
BALANCER .................... 4-37
OIL PUMP ....................... 4-39
KICK SHAFT AND
SHIFT SHAFT ................. 4-42
CDI MAGNETO............... 4-47
ENGINE REMOVAL ....... 4-49
CRANKCASE AND
CRANKSHAFT ............... 4-53
TRANSMISSION,
SHIFT CAM AND
SHIFT FORK................... 4-59
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

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. Front brake lever
4. Throttle grip
5. Radiator cap
6. Fuel tank cap
7. Engine stop switch
8. Kickstarter crank
9. Fuel tank
10. Radiator
11. Coolant drain bolt
12. Rear brake pedal
13. Valve joint14. Fuel cock
15. Cold starter knob
16. Drive chain
17. Air filter
18. Oil level check window
19. Shift pedal
20. Front fork
1

1-2
MACHINE IDENTIFICATION
MACHINE IDENTIFICATION
There are two significant reasons for
knowing the serial number of your
machine:
1. When ordering parts, you can
give the number to your Yamaha
dealer for positive identification of
the model you own.
2. If your machine is stolen, the au-
thorities will need the number to
search for and identify your ma-
chine.
VEHICLE IDENTIFICATION
NUMBER
The vehicle identification number "1"
is stamped on the right of the steering
head pipe.
ENGINE SERIAL NUMBER
The engine serial number "1" is
stamped into the elevated part of the
right-side of the engine.
MODEL LABEL
The model label "1" is affixed to the
frame under the rider's seat. This in-
formation will be needed to order
spare parts.
INCLUDED PARTS
DETACHABLE SIDESTAND
This sidestand "1" is used to support
only the machine when standing or
transporting it.
• Never apply additional force to
the sidestand.
• Remove this sidestand before
starting out.
VALVE JOINT
This valve joint "1" prevents fuel from
flowing out and is installed to the fuel
tank breather hose.
In this installation, make sure the
arrow faces the fuel tank and also
downward.
SPARK PLUG WRENCH
This spark plug wrench "1" is used to
remove and install the spark plug.
NIPPLE WRENCH
This nipple wrench "1" is used to
tighten the spoke.
JET NEEDLE PULL-UP TOOL
The jet needle pull-up tool "1" is used
to pull the jet needle out of the carbu-
retor.HANDLEBAR PROTECTOR
Install the handlebar protector "1" so
that the mark "a" face forward.
IMPORTANT INFORMATION
PREPARATION FOR REMOVAL
AND DISASSEMBLY
1. Remove all dirt, mud, dust, and
foreign material before removal
and disassembly.
• When washing the machine with
high pressured water, cover the
parts follows.
Silencer exhaust port
Side cover air intake port
Water pump housing hole at the
bottom
Drain hole on the cylinder head
(right side)
2. Use proper tools and cleaning
equipment. Refer to "SPECIAL
TOOLS" section.
3. When disassembling the ma-
chine, keep mated parts together.
They include gears, cylinders,
pistons, and other mated parts
that have been "mated" through
normal wear. Mated parts must
be reused as an assembly or re-
placed.

1-5
SPECIAL TOOLS
Radiator cap tester
YU-24460-01, 90890-01325
Radiator cap tester adapter
YU-33984, 90890-01352These tools are used for checking
the cooling system.
Steering nut wrench
YU-33975, 90890-01403 This tool is used when tighten the
steering ring nut to specification.
Cap bolt wrench
YM-01500, 90890-01500This tool is used to loosen or tighten
the base valve.
Cap bolt ring wrench
YM-01501, 90890-01501This tool is used to loosen or tighten
the damper assembly.
Fork seal driver
YM-A0948, 90890-01502 This tool is used when install the fork
oil seal.
Spoke nipple wrench
YM-01521, 90890-01521 This tool is used to tighten the
spoke.
Pocket tester
YU-3112-C, 90890-03112 Use this tool to inspect the coil resis-
tance, output voltage and amper-
age. Tool name/Part number How to use Illustration

1-6
SPECIAL TOOLS
Timing light
YM-33277-A, 90890-03141 This tool is necessary for checking
ignition timing.
Valve spring compressor
YM-4019, 90890-04019 This tool is needed to remove and
install the valve assemblies.
Clutch holding tool
YM-91042, 90890-04086This tool is used to hold the clutch
when removing or installing the
clutch boss securing nut.
Valve guide remover
Intake 4.0 mm (0.16 in)
Exhaust 4.5 mm (0.18 in)
YM-4111, 90890-04111
YM-4116, 90890-04116This tool is needed to remove and
install the valve guide.
Valve guide installer
Intake 4.0 mm (0.16 in)
Exhaust 4.5 mm (0.18 in)
YM-4112, 90890-04112
YM-4117, 90890-04117This tool is needed to install the
valve guide.
Valve guide reamer
Intake 4.0 mm (0.16 in)
Exhaust 4.5 mm (0.18 in)
YM-4113, 90890-04113
YM-4118, 90890-04118This tool is needed to rebore the
new valve guide. Tool name/Part number How to use Illustration

1-8
CONTROL FUNCTIONS
CONTROL FUNCTIONS
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.
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 two 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.COLD STARTER KNOB
When cold, the engine requires a
richer air-fuel mixture for starting. A
separate starter circuit, which is con-
trolled by the cold starter knob "1",
supplies this mixture. Pull the cold
starter knob out to open the circuit for
starting. When the engine has
warmed up, push it in to close the cir-
cuit.
HOT STARTER LEVER
The hot starter lever "1" is used when
starting a warm engine. Use the hot
starter lever when starting the engine
again immediately after it was
stopped (the engine is still warm).
Pulling the hot starter lever injects
secondary air to thin the air-fuel mix-
ture temporarily, allowing the engine
to be started more easily.
STARTING AND BREAK-IN
FUEL
Always use the recommended fuel as
stated below. Also, be sure to use
new gasoline the day of a race.
Use only unleaded gasoline. The
use of leaded gasoline will cause
severe damage to the engine inter-
nal parts such as valves, piston
rings, and exhaust system, etc.
Recommended fuel:
Premium unleaded
gasoline only with a re-
search octane number
of 95 or higher.

1-10
STARTING AND BREAK-IN
BREAK-IN PROCEDURES
1. Before starting the engine, fill the
fuel tank with the fuel.
2. Perform the pre-operation checks
on the machine.
3. Start and warm up the engine.
Check the idle speed, and check
the operation of the controls and
the engine stop switch. Then, re-
start the engine and check its op-
eration within no more than 5
minutes after it is restarted.
4. Operate the machine in the lower
gears at moderate throttle open-
ings for five to eight minutes.
5. Check how the engine runs when
the machine is ridden with the
throttle 1/4 to 1/2 open (low to me-
dium speed) for about one hour.
6. Restart the engine and check the
operation of the machine through-
out its entire operating range. Re-
start the machine and operate it
for about 10 to 15 more minutes.
The machine will now be ready to
race.
• After the break-in or before each
race, you must check the entire
machine for loose fittings and
fasteners as per "TORQUE-
CHECK POINTS". Tighten all
such fasteners as required.
• When any of the following parts
have been replaced, they must
be broken in.
CYLINDER AND CRANKSHAFT:
About one hour of break-in oper-
ation is necessary.
PISTON, RING, VALVES, CAM-
SHAFTS AND GEARS:
These parts require about 30
minutes of break-in operation at
half-throttle or less. Observe the
condition of the engine carefully
during operation.

2-4
MAINTENANCE SPECIFICATIONS
Camshaft runout limit ---- 0.03 mm
(0.0012 in)
Timing chain:
Timing chain type/No. of links 92RH2010-114M/114 ----
Timing chain adjustment method Automatic ----
Valve, valve seat, valve guide:
Valve clearance (cold)
IN 0.10–0.15 mm (0.0039–0.0059 in) ----
EX 0.17–0.22 mm (0.0067–0.0087 in) ----
Valve dimensions:
"A" head diameter (IN) 22.9–23.1 mm (0.9016–0.9094 in) ----
"A" head diameter (EX) 24.4–24.6 mm (0.9606–0.9685 in) ----
"B" face width (IN) 2.26 mm (0.089 in) ----
"B" face width (EX) 2.26 mm (0.089 in) ----
"C" seat width (IN) 0.9–1.1 mm (0.0354–0.0433 in) 1.6 mm (0.0630
in)
"C" seat width (EX) 0.9–1.1 mm (0.0354–0.0433 in) 1.6 mm (0.0630
in)
"D" margin thickness (IN) 0.8 mm (0.0315 in) ----
"D" margin thickness (EX) 0.7 mm (0.0276 in) ----Item Standard Limit