brake YAMAHA WR 250F 2017 Repair Manual

REAR BRAKE
5-31
EAS2GBB191ASSEMBLING THE REAR BRAKE MASTER
CYLINDER
EWA
WARNING
• Before installation, all internal brake com-
ponents should be cleaned and lubricated
with clean or new brake fluid.
• Never use solvents on internal brake com-
ponents.
1. Wash the brake master cylinder and the
brake master cylinder kit with brake fluid.
2. Install:
• Primary cylinder cup “1”
• Secondary cylinder cup “2”
Install to the brake master cylinder piston
“3”.
EWA
WARNING
Apply brake fluid to the cylinder cups and
install them as shown. Wrong orientation in
installation causes poor braking perfor-
mance.
3. Install:
• Spring “1”
Install to the brake master cylinder piston
“2”.
TIP
Install the spring with a smaller inside diameter
to the brake master cylinder piston.4. Install:
• Master cylinder kit “1”
• Push rod “2”
• Circlip “3”
• Dust boot “4”
TIP
• Before installation, apply brake fluid to the
brake master cylinder kit.
• Before installation, apply silicone grease to
the push rod end.
• Use circlip pliers to install the circlip.
EAS2GBB192INSTALLING THE REAR BRAKE MASTER
CYLINDER
1. Install:
• Copper washers
• Brake hose
• Union bolt
EWA
WARNING
Proper brake hose routing is essential to in-
sure safe vehicle operation.
ECA
NOTICE
Make sure that the pipe portion of the brake
hose touches the projection “a” on the
brake caliper. Specified brake fluid
DOT 4
2
3
1
2
3
1Brake hose union bolt
30 Nm (3.0 m·kgf, 22 ft·lbf)
12
New
New
13
4
2NewNew
New
T R..

REAR BRAKE
5-32
2. Pour brake fluid to the brake fluid reservoir
up to the specified level.
EWA
WARNING
• Use only the designated brake fluid. Other
brake fluids may cause the rubber seals to
deteriorate, causing leakage and poor
brake performance.
• Refill with the same type of brake fluid that
is already in the system. Mixing brake flu-
ids may result in a harmful chemical reac-
tion, leading to poor brake performance.
• When refilling, be careful that water does
not enter the brake fluid reservoir. Water
will significantly lower the boiling point of
the brake fluid and could cause vapor
lock.
ECA
NOTICE
Brake fluid may damage painted surfaces
and plastic parts. Therefore, always clean
up any spilt brake fluid immediately.
3. Bleed:
• Brake system
Refer to “BLEEDING THE BRAKE SYS-
TEM” on page 3-25.
4. Check:
• Brake fluid level
The minimum level mark “a” or below 
Add.
Refer to “CHECKING THE BRAKE FLUID
LEVEL” on page 3-30.5. Check:
• Brake pedal operation
A softy or spongy feeling  Bleed the brake
system.
Refer to “BLEEDING THE BRAKE SYS-
TEM” on page 3-25. Specified brake fluid
DOT 4
a
a

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
5-38
9. Install:
• Throttle cable housings “1”
• Screw (throttle cable housings) “2”
EWA
WARNING
After tightening the throttle cable housing
screws, check that the throttle grip “3”
moves smoothly. If it does not, retighten the
screws for adjustment.
10.Install:
• Rubber cover “1”
• Cover (throttle cable housings) “2”11.Install:
• Start switch “1”
• Front brake master cylinder assembly “2”
• Front brake master cylinder holder “3”
• Bolt (brake master cylinder holder) “4”
•Clamp “5”TIP
• Install the brake master cylinder holder with
the “UP” mark facing up.
• Install in order for the top of the front brake
master cylinder assembly to be level.
• First, tighten the upper bolt, then the lower
bolt. Screw (throttle cable housings)
3.8 Nm (0.38 m·kgf, 2.8 ft·lbf)
T R..
Front brake master cylinder hold-
er bolt
9 Nm (0.9 m·kgf, 6.5 ft·lbf)
T R..
2
5
1
4
3
4

FRONT FORK
5-40
EAS2GBB197
FRONT FORK
Removing the front fork legs
Order Part name Q’ty Remarks
Use a suitable stand to raise the front wheel
off the ground.
Front wheel Refer to “FRONT WHEEL” on page 5-4.
Front brake caliper Refer to “FRONT BRAKE” on page 5-13.
1 Brake hose holder 2
2 Protector 1
3 Upper bracket pinch bolts 2 Loosen.
4 Damper assembly 1 Loosen.
5 Lower bracket pinch bolts 2 Loosen.
6 Front fork leg 1
7 Reflector/Stay/Nut 1 For Canada
For installation, reverse the removal proce-
dure.

SWINGARM
5-65
EAS2GBB216
SWINGARM
Removing the swingarm
Order Part name Q’ty Remarks
Use a suitable stand to raise the front wheel
off the ground.
Brake hose holder Refer to “REAR BRAKE” on page 5-23.
Rear brake caliper Refer to “REAR BRAKE” on page 5-23.
Bolt (brake pedal)
Drive chain
1Collars 2
2Oil seals 2
3Thrust bearing 2
4Bushing 2
5Oil seals 2
6Bearing 4
For installation, reverse the removal proce-
dure.
1
2
3
6
4
6
4
1
3
6
2
5
T.R.70 Nm (7.0 mlbf) kgf, 51 ft
T.R.4.0 Nm (0.40 mlbf) kgf, 2.9 ft

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
6-4
Removing the engine
Order Part name Q’ty Remarks
Use a suitable stand to raise the front wheel
off the ground.
Seat Refer to “GENERAL CHASSIS” on page 5-1.
Side cover (left/right) Refer to “GENERAL CHASSIS” on page 5-1.
Air scoop (left/right) Refer to “GENERAL CHASSIS” on page 5-1.
Fuel tank Refer to “FUEL TANK” on page 8-1.
Exhaust pipe and silencer Refer to “ENGINE REMOVAL” on page 6-1.
Air filter case Refer to “THROTTLE BODY” on page 8-7.
Throttle body Refer to “THROTTLE BODY” on page 8-7.
Clutch cable Refer to “CLUTCH” on page 6-42.
Shift pedal Refer to “SHIFT SHAFT” on page 6-54.
Starter motorRefer to “ELECTRIC STARTER” on page 6-
37.
1 Engine guard 1
2 Brake pedal 1
3Spring 1
4 Cylinder head breather hose 1
New
New
LS
M
8
8
7
6
13
45
New
1 12
3
2
1110
9
55 Nm (5.5 m kgf, 40 ft Ibf)T.R.

ENGINE REMOVAL
6-6
EAS2GBB227REMOVING THE SILENCER
1. Remove:
• Rear shock absorber assembly lower bolt
“1”
• Connecting arm bolt (frame side) “2”
• Silencer “3”
TIP
Move the rear shock absorber to the left side of
the chassis, and remove the silencer.
EAS2GBB228REMOVING THE EXHAUST PIPE 2
1. Remove:
• Exhaust pipe 2
TIP
Put the Exhaust pipe 2 into the state as shown
by moving this, and then remove it.
EAS2GBB229REMOVING THE DRIVE SPROCKET
1. Straighten the lock washer tab.
2. Remove:
• Nut (drive sprocket) “1”
• Lock washer “2”
TIP
Loosen the nut while applying the rear brake.
3. Remove:
• Drive sprocket “1”
• Drive chain “2”
TIP
Remove the drive sprocket together with the
drive chain.
1 2
3

ENGINE REMOVAL
6-9
EAS2GBB234INSTALLING THE BRAKE PEDAL
1. Install:
• Spring “1”
• Brake pedal “2”
• O-rings “3”
• Bolt (brake pedal) “4”
•Clip “5”
TIP
Apply the lithium-soap-based grease on the
bolt, O-rings and brake pedal bracket.
EAS2GBB235INSTALLING THE DRIVE SPROCKET
1. Install:
• Drive sprocket “1”
• Drive chain “2”
TIP
Install the drive sprocket together with the drive
chain.
2. Install:
• Lock washer “1”
• Nut (drive sprocket) “2”
TIP
Tighten the nut while applying the rear brake.
ECA
NOTICE
Make sure to tighten to specification; other-
wise, it may damage the other part that is
fastened together.
3. Bend the lock washer tab to lock the nut.
4. Install:
• Drive sprocket guide
• Drive sprocket cover “1”
• Bolt (drive sprocket cover) “2” Bolt (brake pedal)
26 Nm (2.6 m·kgf, 19 ft·lbf)
M
78
9
9 8
7
4 1
2
43
5
56
New
T R..
1 2
3
45
LS
Nut (drive sprocket)
75 Nm (7.5 m·kgf, 54 ft·lbf)
Bolt (drive sprocket cover)
7 Nm (0.7 m·kgf, 5.1 ft·lbf)
New
T R..
T R..