piston YAMAHA YZ250F 2016 User Guide

MAINTENANCE INTERVALS
3-1
EAS1SM9063
MAINTENANCE INTERVALS
EAS1SM9064MAINTENANCE INTERVALSECA@
NOTICE
• After a break-in or before each race, always check the points shown in “TORQUE-CHECK
POINTS” for tightening torques and retighten them. (“TORQUE-CHECK POINTS” on page 1-
23.)
• Periodic inspection is essential in making full use of the machine performance. The life of
parts varies significantly according to the environment in which the machine runs (e.g., rain,
dirt, etc.). Therefore, earlier inspection is required by reference to the list below.
ITEMAfter
break-
inEvery
race
(about
2.5
hours)Every
third
(about
7.5
hours)Every
fifth
(about
12.5
hours)As re-
quiredRemarks
VALVE
Check the valve
clearancesThe engine must be cold.
Inspect Check the valve seats and the
valve faces for wear.
Replace
VALVE SPRING
Inspect Check the free length and the
tilt.
Replace
VALVE LIFTER
Inspect Check for scratches and wear.
Replace
CAMSHAFT Inspect the camshaft surface.
Inspect Inspect the decompression
system.
Replace
CAMSHAFT
SPROCKET
Inspect Check for wear on the teeth
and for damage.
Replace
PISTON
Inspect Inspect crack.
Clean Inspect carbon deposits and
eliminate them.
Replace Replace the piston, piston pin,
piston pin clip, and piston ring
all as a set.

MAINTENANCE INTERVALS
3-2
PISTON RING
Inspect Check the end gap of the pis-
ton ring.
Replace Replace the piston, piston pin,
piston pin clip, and piston ring
all as a set.
PISTON PIN
Inspect
Replace Replace the piston, piston pin,
piston pin clip, and piston ring
all as a set.
CYLINDER HEAD Check the coolant passages
for corrosion.
Inspect carbon deposits and
eliminate them.
Inspect and clean Check for warpage, and re-
place the gasket.
CYLINDER
Inspect and clean Inspect score marks.
Replace Inspect wear.
ENGINE OIL
Inspect Check the engine oil amount.
Replace
OIL FILTER ELE-
MENT
Replace
OIL STRAINER
Clean
CLUTCH
Inspect and adjust Inspect housing, friction plate,
clutch plate and spring.
Replace
TRANSMISSION
Inspect
Replace bearings
SHIFT FORK, SHIFT
CAM, GUIDE BAR
Inspect Inspect wear.ITEMAfter
break-
inEvery
race
(about
2.5
hours)Every
third
(about
7.5
hours)Every
fifth
(about
12.5
hours)As re-
quiredRemarks

ENGINE
3-17
3. Install:
• Digital tachometer
TIP
Get the high tension cord “1” of the ignition coil
pinched in the detector “a” of the digital tachom-
eter.
4. Measure:
• Engine idling speed
Out of specification  Regulate.
5. Adjust:
• Engine idling speed
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Turn the starter knob/idle screw “1” in the di-
rection of “a” or “b” to make an adjustment.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS1SM9086ADJUSTING THE VALVE CLEARANCE
TIP
• This section is intended for those who have
basic knowledge and skill concerning the ser-
vicing of Yamaha motorcycles (e.g., Yamaha
dealers, service engineers, etc.). Those who
have little knowledge and skill concerning ser-
vicing are requested not to undertake inspec-
tion, adjustment, disassembly, or reassembly
only by reference to this manual. It may lead
to servicing trouble and mechanical damage.
• Make sure that the valve clearance is
checked or adjusted while the engine is cold
(at room temperature).
• While the valve clearance is checked or ad-
justed, make sure that the piston is positioned
in the top dead center (TDC).
1. Remove:
• Seat
• Side cover (left/right)
• Air scoop (left/right)
Refer to “GENERAL CHASSIS” on page 4-
1.
• Fuel tank
Refer to “FUEL TANK” on page 7-1.
•ECU
2. Remove:
• Spark plug
• Cylinder head cover
Refer to “CAMSHAFT” on page 5-11.
3. Remove:
• Timing mark accessing screw “1”
• Crankshaft end accessing screw “2”
• O-ring
4. Check:
• Valve clearance
Out of specification  Regulate. Digital tachometer
90890-06760
Digital tachometer
YU-39951-B
Engine idling speed
1900–2100 r/min
Direction “a” Engine idling speed  De-
creases.
Direction “b” Engine idling speed  In-
creases.1 1
a a
1 b
a
Valve clearance (cold)
Intake
0.12–0.19 mm (0.0047–0.0075 in)
Exhaust
0.17–0.24 mm (0.0067–0.0094 in)
1
2

CHASSIS
3-25
b. Loosen the pad pin “2”.
c. Remove the brake caliper “3” from the front
fork.
d. Remove the pad pin and brake pads “4”.
e. Connect the plastic hose “5” to the bleed
screw “6” and place a container under the
end of the plastic hose.
f. Loosen the bleed screw and push the brake
caliper piston in.
EWA
WARNING
Do not reuse the drained brake fluid.
g. Tighten the bleed screw.
h. Install the brake pads “7” and the pad pin.
TIP
• Install the brake pads with their projections “a”
into the brake caliper recesses “b”.
• Temporarily tighten the pad pin at this point.i. Install the brake caliper “8” and tighten the
pad pin “9”.
j. Install the pad pin plug “10”.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
3. Check:
• Brake fluid level
Refer to “CHECKING THE BRAKE FLUID
LEVEL” on page 3-27.
4. Check:
• Brake lever operation
A softy or spongy feeling  Bleed the brake
system.
Refer to “BLEEDING THE BRAKE SYS-
TEM” on page 3-22. Bleed screw
6 Nm (0.6 m·kgf, 4.3 ft·lbf)
3
2
4
6
5
T R..
Bolt (brake caliper)
28 Nm (2.8 m·kgf, 20 ft·lbf)
Pad pin
17 Nm (1.7 m·kgf, 12 ft·lbf)
Pad pin plug
2.5 Nm (0.25 m·kgf, 1.8 ft·lbf)
7
a b
T R..
8
9
T R..
10

CHASSIS
3-26
EAS1SM9093CHECKING THE REAR BRAKE PADS
1. Measure:
• Brake pad thickness “a”
Out of specification  Replace as a set.
TIP
The pads worn up to the indicator “b” grooves
mean that the brake pad thickness limit is
reached.
2. Replace:
• Brake pads
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the protector “1” and the pad pin
plug “2”.
b. Loosen the pad pin “3”.
c. Remove the rear wheel “4” and the brake
caliper “5”.
Refer to “REAR WHEEL” on page 4-7.d. Remove the pad pin “6” and the brake pads
“7”.
e. Connect the plastic hose “8” to the bleed
screw “9” and place a container under the
end of the plastic hose.
f. Loosen the bleed screw and push the brake
caliper piston in.
EWA
WARNING
Do not reuse the drained brake fluid.
g. Tighten the bleed screw.
h. Install the brake pad “10” and the pad pin
“11”.
TIP
• Install the brake pads with their projections “a”
into the brake caliper recesses “b”.
• Temporarily tighten the pad pin at this point. Brake pad lining thickness (inner)
6.4 mm (0.25 in)
Limit
1.0 mm (0.04 in)
Brake pad lining thickness (outer)
6.4 mm (0.25 in)
Limit
1.0 mm (0.04 in)
ba
a
1 2
Bleed screw
6 Nm (0.6 m·kgf, 4.3 ft·lbf)
34
5
7 6
9
8
T R..

4
CHASSIS
GENERAL CHASSIS........................................................................................ 4-1
REMOVING THE LEFT SIDE COVER ....................................................... 4-2
REMOVING THE SEAT ............................................................................. 4-2
REMOVING THE NUMBER PLATE ........................................................... 4-2
FRONT WHEEL................................................................................................ 4-3
REMOVING THE FRONT WHEEL............................................................. 4-4
CHECKING THE FRONT WHEEL ............................................................. 4-4
DISASSEMBLING THE FRONT WHEEL ................................................... 4-5
ASSEMBLING THE FRONT WHEEL ......................................................... 4-5
INSTALLING THE FRONT WHEEL ........................................................... 4-6
REAR WHEEL.................................................................................................. 4-7
REMOVING THE REAR WHEEL ............................................................... 4-8
CHECKING THE REAR WHEEL................................................................ 4-8
DISASSEMBLING THE REAR WHEEL ..................................................... 4-8
CHECKING AND REPLACING THE REAR WHEEL SPROCKET ............ 4-8
ASSEMBLING THE REAR WHEEL ........................................................... 4-9
INSTALLING THE REAR WHEEL.............................................................. 4-9
FRONT BRAKE.............................................................................................. 4-11
INTRODUCTION ...................................................................................... 4-15
CHECKING THE FRONT BRAKE DISC .................................................. 4-15
REMOVING THE FRONT BRAKE CALIPER ........................................... 4-15
DISASSEMBLING THE FRONT BRAKE CALIPER................................. 4-15
CHECKING THE FRONT BRAKE CALIPER ........................................... 4-16
ASSEMBLING THE FRONT BRAKE CALIPER ....................................... 4-16
INSTALLING THE BRAKE CALIPER PISTON ........................................ 4-16
INSTALLING THE FRONT BRAKE CALIPER ......................................... 4-17
REMOVING THE FRONT BRAKE MASTER CYLINDER ........................ 4-18
CHECKING THE FRONT BRAKE MASTER CYLINDER......................... 4-18
ASSEMBLING THE FRONT BRAKE MASTER CYLINDER .................... 4-18
INSTALLING THE FRONT BRAKE MASTER CYLINDER....................... 4-19
REAR BRAKE................................................................................................ 4-21
INTRODUCTION ...................................................................................... 4-25
CHECKING THE REAR BRAKE DISC..................................................... 4-25
REMOVING THE REAR BRAKE CALIPER ............................................. 4-26
DISASSEMBLING THE REAR BRAKE CALIPER ................................... 4-26
CHECKING THE REAR BRAKE CALIPER .............................................. 4-26
ASSEMBLING THE REAR BRAKE CALIPER ......................................... 4-26
INSTALLING THE BRAKE CALIPER PISTON ........................................ 4-27
INSTALLING THE REAR BRAKE CALIPER ............................................ 4-27
REMOVING THE REAR BRAKE MASTER CYLINDER .......................... 4-28
CHECKING THE REAR BRAKE MASTER CYLINDER ........................... 4-28
ASSEMBLING THE REAR BRAKE MASTER CYLINDER....................... 4-29
INSTALLING THE REAR BRAKE MASTER CYLINDER ......................... 4-29

FRONT BRAKE
4-12
Disassembling the front brake caliper
Order Part name Q’ty Remarks
1 Brake caliper piston 2
2 Brake caliper piston dust seal 2
3 Brake caliper piston seal 2
4 Bleed screw 1
For assembly, reverse the disassemble pro-
cedure.
12
34
S
S
BF
BFT R..
S
6 Nm (0.6 m
kgf, 4.3 ft Ibf)

FRONT BRAKE
4-15
EAS1SM9134INTRODUCTIONEWA
WARNING
If you need to disassemble the disc brake
components, observe the following precau-
tions.
• Never disassemble the brake components
unless absolutely necessary.
• If there is any problem with connections
on the hydraulic brake system, perform
the following jobs.
Disassemble the brake system, drain the
brake fluid, and clean it. After that, add a
suitable amount of brake fluid. Then, bleed
it after reassembly.
• Use only brake fluid for washing brake
components.
• Use new brake fluid for cleaning the brake
components.
• Immediately wipe off the spilled brake fluid
to avoid damage to painted surfaces or
plastic parts.
• Handle brake fluid with special care not to
let it enter your eyes so that you may not
lost your eyesight.
• FIRST AID FOR BRAKE FLUID ENTERING
THE EYES:
• Flush with water for 15 minutes and get
immediate medical attention.
EAS1SM9135CHECKING THE FRONT BRAKE DISC
1. Remove:
• Front wheel
Refer to “FRONT WHEEL” on page 4-3.
2. Check:
• Front brake disc
Damage/galling  Replace.
3. Measure:
• Brake disc thickness
Measure the brake disc thickness at a few
different locations.
Out of specification  Replace.4. Install:
• Front wheel
Refer to “FRONT WHEEL” on page 4-3.
EAS1SM9136REMOVING THE FRONT BRAKE CALIPER
TIP
Before disassembling the brake caliper, drain
the brake fluid from the entire brake system.
1. Remove:
• Union bolt
• Copper washers
• Brake hose
TIP
Put the end of the brake hose into a container
and pump out the brake fluid.
EAS1SM9137DISASSEMBLING THE FRONT BRAKE CAL-
IPER
1. Remove:
• Brake caliper piston “1”
• Brake caliper piston dust seal “2”
• Brake caliper piston seals “3”
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Blow compressed air into the brake hose
joint opening to force out the piston from the
brake caliper.
EWA
WARNING
• Cover the brake caliper piston with a rag.
Be careful not to get injured when the pis-
ton is expelled from the brake caliper.
• Never try to pry out the brake caliper pis-
ton.
Brake disc thickness limit
2.5 mm (0.10 in)
3
2
1

FRONT BRAKE
4-16
b. Remove the brake caliper piston dust seal
and the brake caliper piston seal.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS1SM9138CHECKING THE FRONT BRAKE CALIPER
1. Check:
• Brake caliper piston “1”
Rust/scratches/wear  Replace the brake
caliper piston.
• Brake caliper cylinder “2”
Scratches/wear  Replace the brake cali-
per assembly.
• Brake caliper body “3”
Cracks/damage  Replace the brake cali-
per assembly.
• Brake fluid delivery passages
(brake caliper body)
Obstruction  Blow out with compressed
air.
EWA
WARNING
When the brake caliper is disassembled, re-
place the brake caliper piston seal and the
brake caliper piston dust seal with new
ones.
2. Check:
• Brake caliper bracket
Crack/damage  Replace.
EAS1SM9139ASSEMBLING THE FRONT BRAKE CALI-
PER
EWA
WARNING
• Before installation, clean and lubricate the
internal parts. Use new brake fluid for
cleaning and lubricating.
• Never use solvents on internal brake com-
ponents as they will cause the piston seals
to swell and distort.
• When the brake caliper is disassembled,
replace the brake caliper piston seal and
the brake caliper piston dust seal with new
ones.
EAS1SM9140INSTALLING THE BRAKE CALIPER PISTON
1. Clean:
• Brake caliper
• Brake caliper piston seal
• Brake caliper piston dust seal
• Brake caliper piston
Use brake fluid for cleaning.
2. Install:
• Brake caliper piston seals “1”
• Brake caliper piston dust seal “2”
EWA
WARNING
Always use new brake caliper piston seal
and brake caliper piston dust seal.
TIP
• Apply the silicone grease on the brake caliper
piston seal and brake caliper piston dust seal.
• Fit the brake caliper piston seal and the brake
caliper piston dust seal into the grooves in the
brake caliper correctly.
2
113
Specified brake fluid
DOT 4
New
New
1
1
22

FRONT BRAKE
4-17
3. Install:
• Brake caliper piston “1”
TIP
Apply the brake fluid on the piston outer sur-
face.
ECANOTICE
• Install the piston with its side “a” facing
the brake caliper.
• Never force to insert.
EAS1SM9141INSTALLING THE FRONT BRAKE CALIPER
1. Install:
• Front brake caliper bracket
• Front brake caliper
(temporarily)
• Copper washers
• Brake hose
• Union bolt
EWAWARNING
Proper brake hose routing is essential to in-
sure safe vehicle operation.
ECANOTICE
Make sure that the pipe portion “a” of the
brake hose touches the projection “b” on
the brake caliper.2. Install:
• Front brake caliper
• Brake pad spring
• Brake pad
• Brake pad pin
• Brake hose holder
Refer to “CHECKING THE FRONT BRAKE
PADS” on page 3-24.
3. Tighten:
• Brake hose holder mounting bolt “1”
TIP
Make sure that the brake hose holder “2” is in-
stalled with its upper end “a” aligned with the
paint “b” on the brake hose.
4. Pour brake fluid to the brake master cylinder
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
Front brake caliper bracket
28 Nm (2.8 m·kgf, 20 ft·lbf)
Brake hose union bolt
30 Nm (3.0 m·kgf, 22 ft·lbf)
1
a
1
New
T R..
a
b
Brake pad pin
17 Nm (1.7 m·kgf, 12 ft·lbf)
Brake hose holder mounting bolt
9 Nm (0.9 m·kgf, 6.5 ft·lbf)
Specified brake fluid
DOT 4
T R..
T R..
2
1 b
a