2016 YAMAHA YZ250F engine

RADIATOR
6-1
EAS1SM9293
TIP
This section is intended for those who have basic knowledge and skill concerning the servicing of
Yamaha motorcycles (e.g., Yamaha dealers, service engineers, etc.). Those who have little knowl-
edge and skill concerning servicing are requested not to undertake inspection, adjustment, disas-
sembly, or reassembly only by reference to this manual. It may lead to servicing trouble and
mechanical damage.
EAS1SM9294
RADIATOR
Removing the radiator
Order Part name Q’ty Remarks
CoolantDrain.
Refer to “CHANGING THE COOLANT” on
page 3-8.
Seat Refer to “GENERAL CHASSIS” on page 4-1.
Side cover (left/right) Refer to “GENERAL CHASSIS” on page 4-1.
Air scoop (left / right) Refer to “GENERAL CHASSIS” on page 4-1.
Fuel tank Refer to “FUEL TANK” on page 7-1.
Air filter case Refer to “THROTTLE BODY” on page 7-5.
1 Radiator guard 2
2 Radiator hose clamp 8 Loosen.
11
12
New
New
New
LS
LS

WATER PUMP
6-4
EAS1SM9297
WATER PUMP
Removing the water pump
Order Part name Q’ty Remarks
CoolantDrain.
Refer to “CHANGING THE COOLANT” on
page 3-8.
Engine oilDrain.
Refer to “CHANGING THE ENGINE OIL” on
page 3-15.
Right crankcase cover Refer to “CLUTCH” on page 5-35.
1 Water pump housing 1
2 Dowel pin 2
3Gasket 1
4Washer 2
5Collar 1
6Gear 1
7Pin 1
8 Impeller shaft assembly 1
9 Oil seal 1
9
8
2
2
3
1
10
6
7
5
4
4
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
New
New
New
E
11
New
E
LS
LS

WATER PUMP
6-6
EAS1SM9298REMOVING THE OIL SEAL
TIP
• Remove the oil seal when the coolant level
changes frequently more than usual, coolant
has discolored, or engine oil has become
milky.
• Do not use the removed oil seal.
1. Remove:
• Oil seals “1”
EAS1SM9299CHECKING THE WATER PUMP
1. Check:
• Water pump housing cover
• Impeller shaft
Cracks/damage/wear  Replace.
EAS1SM9300CHECKING THE BEARING
1. Check:
• Bearing
Rotate the inner race with your finger.
Rough spot/seizure  Replace.
EAS1SM9301INSTALLING THE OIL SEAL
1. Install:
• Oil seals “1”
TIP
• Apply the lithium-soap-based grease on the
oil seal lip.
• Install the oil seal with its manufacture’s
marks or numbers facing the right crankcase
cover “2”.2. Install:
• Bearing “1”
TIP
Install the bearing by pressing its outer race
parallel.
EAS1SM9302ASSEMBLING THE WATER PUMP
1. Install:
• Impeller shaft assembly “1”
• Washer “2”
•Pin “3”
• Gear “4”
• Collar “5”
• Circlip “6”
TIP
• Take care so that the oil seal lip is not dam-
aged or the spring does not slip off its posi-
tion.
• When installing the impeller shaft, apply the
engine oil to the oil seal lip, the bearing, and
the impeller shaft.
1 1
New
1 1New
New
LS
LS2
New
1
2
52346
New
E

FUEL TANK
7-1
EAS1SM9303
TIP
This section is intended for those who have basic knowledge and skill concerning the servicing of
Yamaha motorcycles (e.g., Yamaha dealers, service engineers, etc.). Those who have little knowl-
edge and skill concerning servicing are requested not to undertake inspection, adjustment, disas-
sembly, or reassembly only by reference to this manual. It may lead to servicing trouble and
mechanical damage.
EAS1SM9304
FUEL TANK
Removing the fuel tank
Order Part name Q’ty Remarks
Seat Refer to “GENERAL CHASSIS” on page 4-1.
Side cover (left/right)
Air scoop (left/right)
1 Fuel pump coupler 1 Disconnect.
2 Fuel hose 1 Disconnect.
3Fuel tank 1
4 Fuel pump bracket 1
5 Fuel pump 1
6 Fuel pump gasket 1
For installation, reverse the removal proce-
dure.
4(6) (2)
(2) (2)(2)2
5
6
3
1
New
4.0 Nm (0.40 m kgf, 2.9 ft Ibf)T.R.
7 Nm (0.7 m kgf, 5.1 ft Ibf)T.R.
7 Nm (0.7 m kgf, 5.1 ft Ibf)T.R.
7 Nm (0.7 m kgf, 5.1 ft Ibf)T.R.
9 Nm (0.9 m kgf, 6.5 ft Ibf)T.R.
4.0 Nm (0.40 m kgf, 2.9 ft Ibf)T.R.
4.0 Nm (0.40 m kgf, 2.9 ft Ibf)T.R.
7

FUEL TANK
7-4
e. Start the engine.
f. Measure the fuel pressure.
Out of specification  Replace the fuel
pump.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲EAS1SM9311CHECKING THE DAMPER
1. Check:
• Damper 1 “1”
• Damper 2 “2”
• Damper 3 “3”
Wear/damage  Replace.
TIP
• Affix dampers 1 and 3 with the arrow on each
damper pointing outward.
• Affix the damper 2 with its projection “a” facing
the rear of the vehicle.
EAS1SM9312CHECKING AND REPLACING THE PRO-
TECTOR
1. Check:
• Protector “1”
Wear/damage  Replace.
TIP
Affix the protector as shown.
Fuel line pressure at idling
324.0 kPa (3.24 kgf/cm
2, 47.0
psi)
1
2
(3.31 in) (4.53 in)
84 mm 115 mm3 1
13a
2
(3.31 in) (4.53 in)84 mm 115 mm
A. Left
B. Right
1
1
A
0 mm
(0 in)
B
1
1
15 mm
(0.59 in)

THROTTLE BODY
7-5
EAS1SM9313
THROTTLE BODY
Removing the throttle body
Order Part name Q’ty Remarks
Seat Refer to “GENERAL CHASSIS” on page 4-1.
Side cover (left/right) Refer to “GENERAL CHASSIS” on page 4-1.
Air scoop (left/right) Refer to “GENERAL CHASSIS” on page 4-1.
Fuel tank Refer to “FUEL TANK” on page 7-1.
ECU Refer to “ENGINE REMOVAL” on page 5-1.
Ignition coil Refer to “ENGINE REMOVAL” on page 5-1.
1 Intake air temperature sensor coupler 1 Disconnect.
2 Air filter case 1
3 Fuel injector coupler 1 Disconnect.
4 Intake air pressure sensor coupler 1 Disconnect.
5 Throttle position sensor coupler 1 Disconnect.
6 Throttle cable cover 1
7 Throttle cable 2
8 Fuel hose 1
9 Exhaust pipe bracket 1
2
1
6
10
11
9
8
3
7
5
4
3.5 Nm (0.35 mkgf, 2.5 ftIbf)T.R.
3.5 Nm (0.35 mkgf, 2.5 ftIbf)T.R.
7 Nm (0.7 mkgf, 5.1 ftIbf)T.R.
3.0 Nm (0.30 mkgf, 2.2 ftIbf)T.R.
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.

THROTTLE BODY
7-8
EAS1SM9314CHECKING THE INJECTOR
1. Check:
• Injectors
Obstruction  Replace, and check the fuel
pump and the fuel injection system.
Refer to “FUEL INJECTION SYSTEM” on
page 8-10.
Deposits  Replace.
Damage  Replace.
2. Check:
• Injector resistance
Refer to “CHECKING THE FUEL INJEC-
TOR” on page 8-47.
EAS1SM9315CHECKING THE THROTTLE BODY
1. Check:
• Throttle body
Cracks/damage  Replace.
2. Check:
• Fuel passages
Obstructions  Clean.
ECA
NOTICE
• Before removing the throttle body, clean
the area around the throttle body to pre-
vent dirt and other foreign material from
falling into the engine.
• If the throttle body is subject to strong
shocks or dropped during cleaning, re-
place it.
• Do not use any caustic carburetor clean-
ing solution.
• Do not directly push the throttle valves to
open them.
• Do not loosen the throttle valve stopper
screw “1”, throttle valve pulley nut “2”, or
throttle valve screw “3”. A loss of perfor-
mance may occur.
• Do not use compressed air to clean the
throttle body. Foreign materials may ad-
here to the intake air pressure sensor pas-
sage “a” and fuel injector “b” in the
throttle body.3. Check:
• Starter knob/idle screw passage “c”
Obstruction  Blow out with compressed
air.
EAS1SM9316CHECKING THE THROTTLE BODY JOINT
1. Check:
• Throttle body joint “1”
Crack/damage  Replace.
1 2
3
ba
c
1

8-1
EAS1SM9318
TIP
This section is intended for those who have basic knowledge and skill concerning the servicing of
Yamaha motorcycles (e.g., Yamaha dealers, service engineers, etc.). Those who have little knowl-
edge and skill concerning servicing are requested not to undertake inspection, adjustment, disas-
sembly, or reassembly only by reference to this manual. It may lead to servicing trouble and
mechanical damage.