2008 YAMAHA YBR125 engine

TABLE OF CONTENTSSAFETY INFORMATION ..................1-1
DESCRIPTION ..................................2-1
Left view ..........................................2-1
Right view ........................................2-2
Controls and instruments.................2-3
INSTRUMENT AND CONTROL
FUNCTIONS.......................................3-1
Main switch/steering lock ................3-1
Indicator and warning lights ............3-2
Speedometer unit ...........................3-2
Tachometer ....................................3-3
Self-diagnosis device ......................3-3
Fuel gauge ......................................3-3
Handlebar switches ........................3-4
Clutch lever .....................................3-5
Shift pedal .......................................3-5
Brake lever .....................................3-5
Brake pedal ....................................3-6
Fuel tank cap ..................................3-6
Fuel .................................................3-7
Catalytic converters ........................3-8
Kickstarter .......................................3-8
Adjusting the shock absorber
assemblies ..................................3-8
Carrier .............................................3-9
Sidestand ........................................3-9
Ignition circuit cut-off system ........3-10PRE-OPERATION CHECKS............. 4-1
Pre-operation check list .................. 4-2
OPERATION AND IMPORTANT
RIDING POINTS................................. 5-1
Starting the engine ......................... 5-1
Shifting ........................................... 5-2
Tips for reducing fuel
consumption ............................... 5-3
Engine break-in .............................. 5-3
Parking ........................................... 5-4
PERIODIC MAINTENANCE AND
MINOR REPAIR................................. 6-1
Owner’s tool kit ............................... 6-1
Periodic maintenance and
lubrication chart .......................... 6-2
Removing and installing panels ..... 6-6
Checking the spark plug ................. 6-7
Engine oil ....................................... 6-9
Cleaning the air filter element ...... 6-10
Checking the engine idling
speed ........................................ 6-12
Adjusting the throttle cable free
play ........................................... 6-12
Valve clearance ............................ 6-13
Tires ............................................. 6-13
Cast wheels .................................. 6-15
Adjusting the clutch lever free
play ........................................... 6-16Checking the front brake lever free
play ........................................... 6-17
Adjusting the brake pedal free
play ........................................... 6-17
Checking the shift pedal .............. 6-18
Adjusting the rear brake light
switch ....................................... 6-18
Checking the front brake pads and
rear brake shoes ...................... 6-19
Checking the front brake fluid
level .......................................... 6-19
Changing the brake fluid .............. 6-20
Drive chain slack .......................... 6-21
Cleaning and lubricating the drive
chain ......................................... 6-22
Checking and lubricating
the cables ................................. 6-23
Checking and lubricating
the throttle grip and cable ......... 6-23
Checking and lubricating
the brake and clutch levers ...... 6-23
Checking and lubricating
the brake pedal ......................... 6-24
Checking and lubricating the
centerstand and sidestand ....... 6-24
Lubricating the swingarm
pivots ........................................ 6-25
Checking the front fork ................. 6-25
Checking the steering .................. 6-26
Checking the wheel bearings ....... 6-26
Battery ......................................... 6-27U27SE0E0.book Page 1 Friday, February 22, 2008 8:54 AM

SAFETY INFORMATION
1-2
1 due to EXCESSIVE SPEED or un-
dercornering (insufficient lean an-
gle for the speed).
Always obey the speed limit and
never travel faster than warrant-
ed by road and traffic conditions.
Always signal before turning or
changing lanes. Make sure that
other motorists can see you.


The posture of the operator and
passenger is important for proper
control.
The operator should keep both
hands on the handlebar and
both feet on the operator foot-
rests during operation to main-
tain control of the motorcycle.
The passenger should always
hold onto the operator, the seat
strap or grab bar, if equipped,
with both hands and keep both
feet on the passenger footrests.
Never carry a passenger unless
he or she can firmly place both
feet on the passenger footrests.


Never ride under the influence of
alcohol or other drugs.


This motorcycle is designed for on-
road use only. It is not suitable for
off-road use.
Protective apparel
The majority of fatalities from motor-
cycle accidents are the result of head
injuries. The use of a safety helmet is
the single most critical factor in the pre-
vention or reduction of head injuries.


Always wear an approved helmet.


Wear a face shield or goggles.
Wind in your unprotected eyes
could contribute to an impairment
of vision that could delay seeing a
hazard.


The use of a jacket, heavy boots,
trousers, gloves, etc., is effective in
preventing or reducing abrasions
or lacerations.


Never wear loose-fitting clothes,
otherwise they could catch on the
control levers, footrests, or wheels
and cause injury or an accident.


Never touch the engine or exhaust
system during or after operation.
They become very hot and cancause burns. Always wear protec-
tive clothing that covers your legs,
ankles, and feet.


A passenger should also observe
the above precautions.
Modifications
Modifications made to this motorcycle
not approved by Yamaha, or the re-
moval of original equipment, may ren-
der the motorcycle unsafe for use and
may cause severe personal injury.
Modifications may also make your
motorcycle illegal to use.
Loading and accessories
Adding accessories or cargo to your
motorcycle can adversely affect stabili-
ty and handling if the weight distribution
of the motorcycle is changed. To avoid
the possibility of an accident, use ex-
treme caution when adding cargo or
accessories to your motorcycle. Use
extra care when riding a motorcycle
that has added cargo or accessories.
Here are some general guidelines to
follow if loading cargo or adding acces-
sories to your motorcycle:
U27SE0E0.book Page 2 Friday, February 22, 2008 8:54 AM

SAFETY INFORMATION
1-4
1 tor and may limit control ability,
therefore, such accessories are
not recommended.


Use caution when adding electri-
cal accessories. If electrical acces-
sories exceed the capacity of the
motorcycle’s electrical system, an
electric failure could result, which
could cause a dangerous loss of
lights or engine power.
Gasoline and exhaust gas


GASOLINE IS HIGHLY FLAMMA-
BLE:
Always turn the engine off when
refueling.
Take care not to spill any gaso-
line on the engine or exhaust
system when refueling.
Never refuel while smoking or in
the vicinity of an open flame.


Never start the engine or let it run
for any length of time in a closed
area. The exhaust fumes are poi-
sonous and may cause loss of
consciousness and death within a
short time. Always operate your
motorcycle in an area that has ad-
equate ventilation.


Always turn the engine off before
leaving the motorcycle unattended
and remove the key from the main
switch. When parking the motor-
cycle, note the following:
The engine and exhaust system
may be hot, therefore, park the
motorcycle in a place where pe-
destrians or children are not like-
ly to touch these hot areas.
Do not park the motorcycle on a
slope or soft ground, otherwise it
may fall over.
Do not park the motorcycle near
a flammable source, (e.g., a ker-
osene heater, or near an open
flame), otherwise it could catch
fire.


When transporting the motorcycle
in another vehicle, make sure that
it is kept upright. If the motorcycle
should lean over, gasoline may
leak out of the fuel tank.


If you should swallow any gaso-
line, inhale a lot of gasoline vapor,
or allow gasoline to get into your
eyes, see your doctor immediately.
If any gasoline spills on your skinor clothing, immediately wash the
affected area with soap and water
and change your clothes.
U27SE0E0.book Page 4 Friday, February 22, 2008 8:54 AM

DESCRIPTION
2-1
2
EAU10410
Left view
1
7
6
5
2,3,4
1. Headlight (page 6-29)
2. Fuse (page 6-28)
3. Battery (page 6-27)
4. Owner’s tool kit (page 6-1)
5. Shock absorber assembly spring preload adjusting ring (page 3-8)
6. Engine oil drain bolt (page 6-9)
7. Shift pedal (page 3-5)U27SE0E0.book Page 1 Friday, February 22, 2008 8:54 AM

DESCRIPTION
2-2
2
EAU10420
Right view
1
6
5
4
3
2
1. Carrier (page 3-9)
2. Air filter element (page 6-10)
3. Engine oil filler cap (page 6-9)
4. Brake pedal (page 3-6)
5. Kickstarter (page 3-8)
6. Shock absorber assembly spring preload adjusting ring (page 3-8)
U27SE0E0.book Page 2 Friday, February 22, 2008 8:54 AM

INSTRUMENT AND CONTROL FUNCTIONS
3-1
3
EAU10460
Main switch/steering lock The main switch/steering lock controls
the ignition and lighting systems, and is
used to lock the steering. The various
positions are described below.
EAU33590
ON
All electrical circuits are supplied with
power; the meter lighting, taillight and
auxiliary light come on, and the engine
can be started. The key cannot be re-
moved.NOTE:The headlight comes on automatically
when the engine is started and stays on
until the key is turned to “OFF”, even ifthe engine stalls.
EAU10660
OFF
All electrical systems are off. The key
can be removed.
EAU43140
LOCK
The steering is locked, and all electrical
systems are off. The key can be re-
moved.
To lock the steering1. Turn the handlebars all the way to
the left.
2. Push the key in from the “OFF” po-
sition, and then turn it to “LOCK”
while still pushing it.
3. Remove the key.To unlock the steering
Insert the key and turn it to “OFF”.
WARNING
EWA10060
Never turn the key to “OFF” or
“LOCK” while the vehicle is moving,
otherwise the electrical systems will
be switched off, which may result in
loss of control or an accident. Make
sure that the vehicle is stopped be-
fore turning the key to “OFF” or“LOCK”.
1. Push.
2. Turn.
1. Turn.
U27SE0E0.book Page 1 Friday, February 22, 2008 8:54 AM

INSTRUMENT AND CONTROL FUNCTIONS
3-2
3
EAU11003
Indicator and warning lights
EAU11020
Turn signal indicator light“”
This indicator light flashes when the
turn signal switch is pushed to the left or
right.
EAU11060
Neutral indicator light“”
This indicator light comes on when the
transmission is in the neutral position.
EAU11080
High beam indicator light“”
This indicator light comes on when the
high beam of the headlight is switched
on.
EAU45740
Engine trouble warning light“”
This warning light comes on or flashes
when an electrical circuit monitoring the
engine is defective. When this occurs,
have a Yamaha dealer check the self-
diagnosis system. (See page 3-3 for an
explanation of the self-diagnosis de-
vice.)
The electrical circuit of the warning light
can be checked by turning the key to
“ON”. If the warning light does not come
on for a few seconds, then go off, have
a Yamaha dealer check the electrical
circuit.
EAU11630
Speedometer unit The speedometer unit is equipped with
a speedometer, an odometer and a
tripmeter. The speedometer shows
riding speed. The odometer shows the
total distance traveled. The tripmeter
shows the distance traveled since it
was last set to zero with the reset knob.
The tripmeter can be used to estimate
the distance that can be traveled with a
full tank of fuel. This information will en-
able you to plan future fuel stops.
1. Turn signal indicator light“”
2. Neutral indicator light“”
3. High beam indicator light“”
4. Engine trouble warning light“”
1
2
3
4
1. Speedometer
2. Odometer
3. Tripmeter
4. Tripmeter reset knob
14
32
U27SE0E0.book Page 2 Friday, February 22, 2008 8:54 AM

INSTRUMENT AND CONTROL FUNCTIONS
3-3
3
EAU11851
Tachometer The electric tachometer allows the rider
to monitor the engine speed and keep it
within the ideal power range.CAUTION:
ECA10031
Do not operate the engine in the ta-
chometer red zone.Red zone: 10000 r/min and above
EAU12090
Self-diagnosis device This model is equipped with a self-diag-
nosis device for various electrical cir-
cuits.
If any of those circuits are defective, the
engine trouble warning light will come
on or flash. If this occurs, have a
Yamaha dealer check the vehicle.CAUTION:
ECA11170
To prevent engine damage, be sure
to consult a Yamaha dealer as soonas possible if this occurs.
EAU37052
Fuel gauge The fuel gauge indicates the amount of
fuel in the fuel tank. The needle moves
towards “E” (Empty) as the fuel level
decreases. When the needle reaches
the red zone, approximately 3.0 L (0.79
US gal, 0.66 Imp.gal) remain in the fuel
tank. If this occurs, refuel as soon as
possible.NOTE:The main switch must be turned to
“ON” for the fuel gauge to display anaccurate fuel level reading.
1. Tachometer
2. Tachometer red zone
1
2
1. Fuel gauge
2. Red zone
12
U27SE0E0.book Page 3 Friday, February 22, 2008 8:54 AM