2008 YAMAHA YBR125 transmission

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
3-5
3
EAU12820
Clutch lever The clutch lever is located at the left
handlebar grip. To disengage the
clutch, pull the lever toward the handle-
bar grip. To engage the clutch, release
the lever. The lever should be pulled
rapidly and released slowly for smooth
clutch operation.
The clutch lever is equipped with a
clutch switch, which is part of the igni-
tion circuit cut-off system. (See page
3-10.)
EAU12870
Shift pedal The shift pedal is located on the left
side of the engine and is used in com-
bination with the clutch lever when
shifting the gears of the 5-speed con-
stant-mesh transmission equipped on
this motorcycle.
EAU12890
Brake lever The brake lever is located at the right
handlebar grip. To apply the front
brake, pull the lever toward the handle-
bar grip.
1. Clutch lever
1. Shift pedal
1
1. Brake lever
1
U27SE0E0.book Page 5 Friday, February 22, 2008 8:54 AM

INSTRUMENT AND CONTROL FUNCTIONS
3-10
3below and have a Yamaha dealer re-
pair it if it does not function proper-
ly.
EAU43161
Ignition circuit cut-off system The ignition circuit cut-off system (com-
prising the sidestand switch, clutch
switch and neutral switch) has the fol-
lowing functions.

It prevents starting when the trans-
mission is in gear and the side-
stand is up, but the clutch lever is
not pulled.


It prevents starting when the trans-
mission is in gear and the clutch le-
ver is pulled, but the sidestand is
still down.


It cuts the running engine when the
transmission is in gear and the sid-
estand is moved down.
Periodically check the operation of the
ignition circuit cut-off system according
to the following procedure.WARNING
EWA10260


The vehicle must be placed on
the centerstand during this in-
spection.


If a malfunction is noted, have a
Yamaha dealer check the sys-tem before riding.
U27SE0E0.book Page 10 Friday, February 22, 2008 8:54 AM

INSTRUMENT AND CONTROL FUNCTIONS
3-11
3
With the engine turned off:
1. Move the sidestand down.
2. Turn the key on.
3. Shift the transmission into the neutral position.
4. Push the start switch or push the kickstarter lever down.
Does the engine start?
With the engine still running:
5. Move the sidestand up.
6. Keep the clutch lever pulled.
7. Shift the transmission into gear.
8. Move the sidestand down.
Does the engine stall?
After the engine has stalled:
9. Move the sidestand up.
10. Keep the clutch lever pulled.
11. Push the start switch or push the kickstarter lever down.
Does the engine start?
The system is OK. The motorcycle can be ridden.The neutral switch may be defective.
The motorcycle should not be ridden until
checked by a Yamaha dealer.
The sidestand switch may be defective.
The motorcycle should not be ridden until
checked by a Yamaha dealer.
The clutch switch may be defective.
The motorcycle should not be ridden until
checked by a Yamaha dealer.
YES NO YES NO YES NO
U27SE0E0.book Page 11 Friday, February 22, 2008 8:54 AM

OPERATION AND IMPORTANT RIDING POINTS
5-1
5
EAU15950
WARNING
EWA10270


Become thoroughly familiar
with all operating controls and
their functions before riding.
Consult a Yamaha dealer re-
garding any control or function
that you do not thoroughly un-
derstand.


Never start the engine or oper-
ate it in a closed area for any
length of time. Exhaust fumes
are poisonous, and inhaling
them can cause loss of con-
sciousness and death within a
short time. Always make sure
that there is adequate ventila-
tion.


Before starting out, make sure
that the sidestand is up. If the
sidestand is not raised com-
pletely, it could contact the
ground and distract the opera-
tor, resulting in a possible lossof control.
EAU45310
NOTE:This model is equipped with a lean an-
gle sensor to stop the engine in case of
a turnover. To start the engine after a
turnover, be sure to turn the main
switch to “OFF” and then to “ON”. Fail-
ing to do so will prevent the engine from
starting even though the engine willcrank when pushing the start switch.
EAU43181
Starting the engine In order for the ignition circuit cut-off
system to enable starting, one of the
following conditions must be met:

The transmission is in the neutral
position.


The transmission is in gear with
the clutch lever pulled and the sid-
estand up.WARNING
EWA10290


Before starting the engine,
check the function of the igni-
tion circuit cut-off system ac-
cording to the procedure
described on page 3-10.


Never ride with the sidestanddown.
1. Turn the key to “ON”.
2. Shift the transmission into the neu-
tral position.
NOTE:When the transmission is in the neutral
position, the neutral indicator light
should be on, otherwise have a
Yamaha dealer check the electrical cir-cuit.
U27SE0E0.book Page 1 Friday, February 22, 2008 8:54 AM

OPERATION AND IMPORTANT RIDING POINTS
5-2
53. Start the engine by pushing the
start switch or by pushing the kick-
starter lever down.
NOTE:If the engine fails to start when using
the start switch, release it, wait a few
seconds, and then try again. Each
starting attempt should be as short as
possible to preserve the battery. Do not
crank the engine more than 10 seconds
on any one attempt. If the engine does
not start with the starter motor, try usingthe kickstarter.CAUTION:
ECA11370
The engine trouble warning light
should come on when the key is
turned to “ON”, and then go off after
a few seconds. If the engine trouble
warning light comes on or flashes
after starting, immediately stop the
engine, and have a Yamaha dealercheck the self-diagnosis system.
CAUTION:
ECA11040
For maximum engine life, never ac-
celerate hard when the engine iscold!
EAU16671
Shifting Shifting gears lets you control the
amount of engine power available for
starting off, accelerating, climbing hills,
etc.
The gear positions are shown in the il-
lustration.NOTE:To shift the transmission into the neu-
tral position, press the shift pedal down
repeatedly until it reaches the end of itstravel, and then slightly raise it.1. Shift pedal
2. Neutral position
U27SE0E0.book Page 2 Friday, February 22, 2008 8:54 AM

OPERATION AND IMPORTANT RIDING POINTS
5-3
5
CAUTION:
ECA10260


Even with the transmission in
the neutral position, do not
coast for long periods of time
with the engine off, and do not
tow the motorcycle for long dis-
tances. The transmission is
properly lubricated only when
the engine is running. Inade-
quate lubrication may damage
the transmission.


Always use the clutch while
changing gears to avoid damag-
ing the engine, transmission,
and drive train, which are not
designed to withstand theshock of forced shifting.
EAU16810
Tips for reducing fuel con-
sumption Fuel consumption depends largely on
your riding style. Consider the following
tips to reduce fuel consumption:

Shift up swiftly, and avoid high en-
gine speeds during acceleration.


Do not rev the engine while shifting
down, and avoid high engine
speeds with no load on the engine.


Turn the engine off instead of let-
ting it idle for an extended length of
time (e.g., in traffic jams, at traffic
lights or at railroad crossings).
EAU16830
Engine break-in There is never a more important period
in the life of your engine than the period
between 0 and 1000 km (600 mi). For
this reason, you should read the follow-
ing material carefully.
Since the engine is brand new, do not
put an excessive load on it for the first
1000 km (600 mi). The various parts in
the engine wear and polish themselves
to the correct operating clearances.
During this period, prolonged full-throt-
tle operation or any condition that might
result in engine overheating must be
avoided.
EAU37250
0–500 km (0–300 mi)
Avoid prolonged operation above 6000
r/min.
After every hour of operation, stop the
engine, and then let it cool for five to ten
minutes.
Vary the engine speed from time to
time. Do not operate the engine at one
set throttle position.
U27SE0E0.book Page 3 Friday, February 22, 2008 8:54 AM

PERIODIC MAINTENANCE AND MINOR REPAIR
6-21
6
EAU22760
Drive chain slack The drive chain slack should be
checked before each ride and adjusted
if necessary.
EAU22793
To check the drive chain slack
1. Place the motorcycle on the cen-
terstand.
2. Shift the transmission into the neu-
tral position.
3. Spin the rear wheel several times
to locate the tightest portion of the
drive chain.
4. Measure the drive chain slack as
shown.5. If the drive chain slack is incorrect,
adjust it as follows.
EAU37112
To adjust the drive chain slack
1. Loosen the brake pedal free play
adjusting nut, brake torque rod nut,
and axle nut.
2. Loosen the chain puller locknut at
each end of the swingarm.3. To tighten the drive chain, turn the
adjusting bolt at each end of the
swingarm in direction (a). To loos-
en the drive chain, turn the adjust-
ing bolt at each end of the
swingarm in direction (b), and then
push the rear wheel forward.
NOTE:Using the alignment marks on each
side of the swingarm, make sure that
both chain pullers are in the same posi-tion for proper wheel alignment.
1. Drive chain slack
Drive chain slack:
20.0–30.0 mm (0.79–1.18 in)
1. Drive chain slack adjusting bolt
2. Chain puller locknut
3. Axle nut
4. Brake torque rod nut
5. Brake pedal free play adjusting nut
4
5 12
3
1. Alignment marks
2. Chain puller locknut
3. Drive chain slack adjusting bolt
U27SE0E0.book Page 21 Friday, February 22, 2008 8:54 AM