2010 YAMAHA YBR125 transmission

INSTRUMENT AND CONTROL FUNCTIONS
3-2
3To unlock the steering
Insert the key and turn it to “OFF”.
EAU11004
Indicator and warning lights
EAU11030
Turn signal indicator lights“”
and“”
The corresponding indicator light flash-
es 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.
EAU11505
Engine trouble warning light“”
This warning light comes on or flashes
if a problem is detected in the electrical
circuit monitoring the engine. If this oc-
curs, have a Yamaha dealer check the
self-diagnosis system. (See page 3-3
for an explanation of the self-diagnosis
device.)
The electrical circuit of the warning light
can be checked by turning the key to
“ON”. The warning light should come
on for a few seconds, and then go off.
If the warning light does not come on
initially when the key is turned to “ON”,
or if the warning light remains on, have
a Yamaha dealer check the electrical
circuit.
1. Turn.
LOCKOFF
1
1. Left turn signal indicator light“”
2. Neutral indicator light“”
3. Engine trouble warning light“”
4. High beam indicator light“”
5. Right turn signal indicator light“”
5
4
3
2
1
U51DE0E0.book Page 2 Monday, November 2, 2009 10:34 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
3-11.)
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
U51DE0E0.book Page 5 Monday, November 2, 2009 10:34 AM

INSTRUMENT AND CONTROL FUNCTIONS
3-11
3
EAU43162
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
sidestand is moved down.
Periodically check the operation of the
ignition circuit cut-off system according
to the following procedure.
U51DE0E0.book Page 11 Monday, November 2, 2009 10:34 AM

INSTRUMENT AND CONTROL FUNCTIONS
3-12
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 sidestand switch may not be working correctly.
The motorcycle should not be ridden until
checked by a Yamaha dealer.
The clutch switch may not be working correctly.
The motorcycle should not be ridden until
checked by a Yamaha dealer.
YES NO YES NO YES NO
The neutral switch may not be working correctly.
The motorcycle should not be ridden until
checked by a Yamaha dealer.• The vehicle must be placed on the center-
stand during this inspection.• If a malfunction is noted, have a Yamaha
dealer check the system before riding.
WARNING
U51DE0E0.book Page 12 Monday, November 2, 2009 10:34 AM

OPERATION AND IMPORTANT RIDING POINTS
5-1
5
EAU15951
Read the Owner’s Manual carefully to
become familiar with all controls. If
there is a control or function you do not
understand, ask your Yamaha dealer.
WARNING
EWA10271
Failure to familiarize yourself with
the controls can lead to loss of con-
trol, which could cause an accident
or injury.
EAU45310
TIPThis 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 will
crank when pushing the start switch.
EAU43185
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
sidestand up.
See page 3-11 for more informa-
tion.
1. Turn the key to “ON”.
The engine trouble warning light
should come on for a few seconds,
then go off.
NOTICE
ECA16711
If the warning light does not come
on initially when the key is turned to
“ON”, or if the warning light remains
on, see page 3-2 for the warning light
circuit check.2. Shift the transmission into the neu-
tral position. (See page 5-2.) The
neutral indicator light should come
on. If not, ask a Yamaha dealer to
check the electrical circuit.
U51DE0E0.book Page 1 Monday, November 2, 2009 10:34 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. NOTICE: For
maximum engine life, never ac-
celerate hard when the engine is
cold!
[ECA11041]
If the engine fails to start when us-
ing 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 us-
ing the kickstarter.
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.TIPTo shift the transmission into the neu-
tral position, press the shift pedal down
repeatedly until it reaches the end of its
travel, and then slightly raise it.
NOTICE
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 the
shock of forced shifting.
1. Shift pedal
2. Neutral position
U51DE0E0.book Page 2 Monday, November 2, 2009 10:34 AM

PERIODIC MAINTENANCE AND ADJUSTMENT
6-20
6
EAU22721
Changing the brake fluid Have a Yamaha dealer change the
brake fluid at the intervals specified in
the TIP after the periodic maintenance
and lubrication chart. In addition, have
the oil seals of the brake master cylin-
der and caliper as well as the brake
hose replaced at the intervals listed be-
low or whenever they are damaged or
leaking.

Oil seals: Replace every two
years.


Brake hose: Replace every four
years.
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.
EAUP0060
To adjust the drive chain slack
1. Remove the brake torque rod cot-
ter pin, and then loosen the brake
pedal free play adjusting nut,
brake torque rod nut, and axle nut.
2. Loosen the drive chain puller lock-
nut at each end of the swingarm.
1. Drive chain slack
Drive chain slack:
20.0–30.0 mm (0.79–1.18 in)1. Drive chain slack adjusting bolt
2. Drive chain puller locknut
3. Axle nut
4. Brake torque rod nut
5. Brake torque rod cotter pin
6. Brake pedal free play adjusting nut
1
2
34
5
6
U51DE0E0.book Page 20 Monday, November 2, 2009 10:34 AM

SPECIFICATIONS
8-1
8
Dimensions:Overall length:
1985 mm (78.1 in)
Overall width:
745 mm (29.3 in)
Overall height:
1080 mm (42.5 in)
Seat height:
780 mm (30.7 in)
Wheelbase:
1290 mm (50.8 in)
Ground clearance:
160 mm (6.30 in)
Minimum turning radius:
2270 mm (89.4 in)Weight:With oil and fuel:
125 kg (276 lb)Engine:Engine type:
Air cooled 4-stroke, SOHC
Cylinder arrangement:
Forward-inclined single cylinder
Displacement:
123 cm³
Bore × stroke:
54.0 × 54.0 mm (2.13 × 2.13 in)
Compression ratio:
10.00 :1
Starting system:
Electric starter and kickstarter
Lubrication system:
Wet sump
Engine oil:Recommended brand:
YAMALUBE
Type:
SAE 10W-30, 10W-40, 10W-50, 15W-40,
20W-40 or 20W-50
Recommended engine oil grade:
API service SG type or higher, JASO
standard MA
Engine oil quantity:
Periodic oil change:
1.00 L (1.06 US qt, 0.88 Imp.qt)Air filter:Air filter element:
Dry elementFuel:Recommended fuel:
Regular unleaded gasoline only
Fuel tank capacity:
13.0 L (3.43 US gal, 2.86 Imp.gal)
Fuel reserve amount:
3.4 L (0.90 US gal, 0.75 Imp.gal)
Fuel injection:Throttle body:
ID mark:
51D1 00Spark plug(s):Manufacturer/model:
NGK/CR6HSA
Spark plug gap:
0.6–0.7 mm (0.024–0.028 in)Clutch:Clutch type:
Wet, multiple-discTransmission:Primary reduction system:
Helical gear
Primary reduction ratio:
68/20 (3.400)
Secondary reduction system:
Chain drive
Secondary reduction ratio:
45/14 (3.214)
Transmission type:
Constant mesh 5-speed
Operation:
Left foot operation
Gear ratio:
1st:
37/14 (2.643)
2nd:
32/18 (1.778)
3rd:
25/19 (1.316)
4th:
23/22 (1.045)
–20 –10 0
1020 30 40 50 C 10 30 50 70 90 110 0 130 F
SAE 10W-30
SAE 15W-40SAE 20W-40SAE 20W-50
SAE 10W-40SAE 10W-50
U51DE0E0.book Page 1 Monday, November 2, 2009 10:34 AM