2017 YAMAHA WR 250F engine

GENERAL CHASSIS
5-1
EAS2GBB150
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.
EAS2GBB151
GENERAL CHASSIS
Removing the seat and side cover
Order Part name Q’ty Remarks
1 Seat 1
2 Air scoop (left) 1
3 Air scoop (right) 1
4 Side cover (left) 1
5 Side cover (right) 1
6 Rear fender 1
For installation, reverse the removal proce-
dure.
4 (2)
65
1
3
2
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.
22 Nm (2.2 m kgf, 16 ft Ibf)T.R.
1.3 Nm (0.13 m kgf, 0.94 ft Ibf)T.R.16 Nm (1.6 m kgf, 12 ft Ibf)T.R.

HANDLEBAR
5-33
EAS2GBB193
HANDLEBAR
Removing the handlebar
Order Part name Q’ty Remarks
1 Clutch cable 1 Disconnect.
2 Clutch switch 1
3 Clutch lever holder 1
4 Engine stop switch 1
5 Brake master cylinder 1
6 Throttle cable cap 1
7 Throttle cable (pull) 1 Disconnect.
8 Throttle cable (return) 1 Disconnect.
9 Right grip 1
10 Tube guide 1
11 Start switch 1
12 Left grip 1
13 Upper handlebar holder 2
14 Handlebar 1

HANDLEBAR
5-37
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
5. Install:
• Engine stop switch “1”
• Clutch lever “2”
• Clutch lever holder “3”
•Clamp “4”
TIP
• The engine stop switch, the clutch lever, and
the clutch lever holder should be installed ac-
cording to the dimensions shown.
• Pass the engine stop switch lead through the
middle of the clutch lever holder.
6. Install:
• Right grip “1”
• Collar “2”
Apply adhesive to the tube guide “3”.
TIP
• Before applying the adhesive, wipe off grease
or oil on the tube guide surface “a” with a lac-
quer thinner.
• Install the grip to the tube guide so that the
grip match mark “b” and tube guide slot “c”
form the angle as shown.7. Install:
• Rubber cover “1”
• Throttle grip “2”
TIP
Apply the lithium-soap-based grease on the
throttle grip sliding surface.
8. Install:
• Throttle cables “1”
TIP
Slightly coat the end of throttle cable and inside
of throttle grip with lithium-soap-based grease.
Then, mount the throttle grip onto the handle-
bar. Engine stop switch screw
0.5 Nm (0.05 m·kgf, 0.36 ft·lbf)
Clutch lever holder bolt
3.8 Nm (0.38 m·kgf, 2.8 ft·lbf)
T R..
64
1b
c
3 64

CHAIN DRIVE
5-68
EAS2GBB221
CHAIN DRIVE
Removing the drive chain
Job Order Part name Q’ty Servicing Information
Drive sprocket Refer to “ENGINE REMOVAL” on page 6-1.
1 Drive chain 1
For installation, reverse the removal proce-
dure.
1
T.R.75 Nm (7.5 mlbf) kgf, 54 ft
T.R.7 Nm (0.7 mlbf) kgf, 5.1 ft

CHAIN DRIVE
5-71
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. When press fitting the connecting plate “1”,
make sure the space “a” between the end of
the connecting pin “2” and the connecting
plate is 1.2–1.4 mm (0.05–0.06 in).
b. After riveting, make sure the diameter be-
tween the edges “b” of the connecting pin “2”
is 5.5–5.8 mm (0.22–0.23 in).
c. After riveting, make sure the space “c”,
which is inside of the connecting link “3” and
inside of the connecting plate “1”, is 14.1–
14.3 mm (0.56–0.65 in).
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
2. Lubricate:
•Drive chain3. Install:
• Drive sprocket
• Lock washer
• Drive sprocket nut
Refer to “ENGINE REMOVAL” on page 6-1.
ECA
NOTICE
Never install a new drive chain onto worn
drive chain sprockets; this will dramatically
shorten the drive chain’s life.
4. Adjust:
• Drive chain slack
Refer to “ADJUSTING THE DRIVE CHAIN
SLACK” on page 3-31.
ECA
NOTICE
A drive chain that is too tight will overload
the engine and other vital parts, and one
that is too loose can skip and damage the
swingarm or cause an accident. Therefore,
keep the drive chain slack within the speci-
fied limits.
Recommended lubricant
Chain lubricant suitable for O-
ring chains
Drive sprocket nut
75 Nm (7.5 m·kgf, 54 ft·lbf)
Drive chain slack (on a suitable
stand)
50.0–60.0 mm (1.97–2.36 in)
New
T R..

6
ENGINE
ENGINE REMOVAL......................................................................................... 6-1
REMOVING THE SILENCER ..................................................................... 6-6
REMOVING THE EXHAUST PIPE 2.......................................................... 6-6
REMOVING THE DRIVE SPROCKET ....................................................... 6-6
REMOVING THE ENGINE ......................................................................... 6-7
CLEANING THE SPARK ARRESTER ....................................................... 6-7
CHECKING THE SILENCER AND EXHAUST PIPE.................................. 6-8
INSTALLING THE ENGINE........................................................................ 6-8
INSTALLING THE BRAKE PEDAL ............................................................ 6-9
INSTALLING THE DRIVE SPROCKET...................................................... 6-9
INSTALLING THE EXHAUST PIPE AND MUFFLER............................... 6-10
CAMSHAFT.................................................................................................... 6-12
REMOVING THE CAMSHAFT ................................................................. 6-14
CHECKING THE CAMSHAFT.................................................................. 6-15
CHECKING THE TIMING CHAIN AND CAMSHAFT SPROCKET .......... 6-16
CHECKING THE TIMING CHAIN TENSIONERS .................................... 6-16
CHECKING THE DECOMPRESSION SYSTEM...................................... 6-17
INSTALLING THE CAMSHAFTS ............................................................. 6-17
CYLINDER HEAD........................................................................................... 6-20
REMOVING THE CYLINDER HEAD........................................................ 6-22
CHECKING THE TIMING CHAIN GUIDE (INTAKE SIDE) ...................... 6-22
CHECKING THE CYLINDER HEAD ........................................................ 6-22
INSTALLING THE CYLINDER HEAD ...................................................... 6-23
VALVES AND VALVE SPRINGS................................................................... 6-24
REMOVING THE VALVES ....................................................................... 6-25
CHECKING THE VALVES AND VALVE GUIDES ................................... 6-26
CHECKING THE VALVE SEATS ............................................................. 6-27
CHECKING THE VALVE SPRINGS......................................................... 6-29
CHECKING THE VALVE LIFTERS .......................................................... 6-29
INSTALLING THE VALVES ..................................................................... 6-30
CYLINDER AND PISTON............................................................................... 6-32
REMOVING THE PISTON ....................................................................... 6-33
CHECKING THE CYLINDER AND PISTON ............................................ 6-33
CHECKING THE PISTON RINGS............................................................ 6-34
CHECKING THE PISTON PIN ................................................................. 6-35
INSTALLING THE PISTON AND CYLINDER .......................................... 6-35
ELECTRIC STARTER.................................................................................... 6-37
CHECKING THE STARTER MOTOR ...................................................... 6-39
ASSEMBLING THE STARTER MOTOR .................................................. 6-40

ENGINE REMOVAL
6-1
EAS2GBB225
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.
EAS2GBB226
ENGINE REMOVAL
Removing the exhaust pipe
Order Part name Q’ty Remarks
Refer to “INSTALLING THE EXHAUST
PIPE AND MUFFLER” on page 6-10.
Side cover (right) Refer to “GENERAL CHASSIS” on page 5-1.
Rear shock absorber assembly lower boltRefer to “REAR SHOCK ABSORBER AS-
SEMBLY” on page 5-58.
Connecting arm bolt (frame side)Refer to “REAR SHOCK ABSORBER AS-
SEMBLY” on page 5-58.
1 Silencer clamp 1 Loosen.
2 Silencer 1
3 Exhaust pipe 2 clamp 1 Loosen.
4 Exhaust pipe 2 1
105 9
26
1
66
3
84 7 (4) (6)
30 Nm (3.0 m kgf, 22 ft Ibf)T
.R.
30 Nm (3.0 m kgf, 22 ft Ibf)T
.R.
New
New
10 Nm (1.0 m kgf, 7.2 ft Ibf)T.R.
12 Nm (1.2 m kgf, 8.7 ft Ibf)T.R.12 Nm (1.2 m kgf, 8.7 ft Ibf)T.R.
20 Nm (2.0 m kgf, 14 ft Ibf)T
.R.New
LT
LT
10 Nm (1.0 m kgf, 7.2 ft Ibf)T.R.9 Nm (0.9 m kgf, 6.5 ft Ibf)T
.R.
5 Nm (0.5 m kgf, 3.6 ft Ibf)T
.R.
T
.R.*kgf 13 Nm (1.3 m , 9.4 ft lbf)
kgf, 14 ft 20 Nm (2.0 m lbf)
*

ENGINE REMOVAL
6-2
5 Exhaust pipe 1 1
6 Gaskets 3
7 Exhaust pipe 1 protector 1
8 Exhaust pipe 2 protector 1
9 Silencer cap 1
10 Spark arrester 1
For installation, reverse the removal proce-
dure.
Removing the exhaust pipe
Order Part name Q’ty Remarks
105 9
26
1
66
3
84 7 (4) (6)
30 Nm (3.0 m kgf, 22 ft Ibf)T
.R.
30 Nm (3.0 m kgf, 22 ft Ibf)T
.R.
New
New
10 Nm (1.0 m kgf, 7.2 ft Ibf)T.R.
12 Nm (1.2 m kgf, 8.7 ft Ibf)T.R.12 Nm (1.2 m kgf, 8.7 ft Ibf)T.R.
20 Nm (2.0 m kgf, 14 ft Ibf)T
.R.New
LT
LT
10 Nm (1.0 m kgf, 7.2 ft Ibf)T.R.9 Nm (0.9 m kgf, 6.5 ft Ibf)T
.R.
5 Nm (0.5 m kgf, 3.6 ft Ibf)T
.R.
T
.R.*kgf 13 Nm (1.3 m , 9.4 ft lbf)
kgf, 14 ft 20 Nm (2.0 m lbf)