2021 YAMAHA MT-125 ECU

Safety information
1-5
1operator and may limit control
ability, therefore, such accesso-
ries are not recommended.
 Use caution when adding electri-
cal accessories. If electrical ac-
cessories exceed the capacity of
the motorcycle’s electrical sys-
tem, an electric failure could re-
sult, which could cause a
dangerous loss of lights or engine
power.
Aftermarket Tires an d Rims
The tires and rims that came with your
motorcycle were designed to match
the performance capabilities and to
provide the best combination of han-
dling, braking, and comfort. Other
tires, rims, sizes, and combinations
may not be appropriate. See page 6-17
for tire specifications and for informa-
tion on servicing and replacing your
tires.
Transportin g the Motorcycle
Be sure to observe following instruc-
tions before transporting the motorcy-
cle in another vehicle. 
Remove all loose items from the
motorcycle.
 Check that the fuel cock (if
equipped) is in the off position and
that there are no fuel leaks.
 Shift the transmission into gear
(for models with a manual trans-
mission).
 Secure the motorcycle with tie-
downs or suitable straps that are
attached to solid parts of the mo-
torcycle, such as the frame or up-
per front fork triple clamp (and not,
for example, to rubber-mounted
handlebars or turn signals, or
parts that could break). Choose
the location for the straps carefully
so the straps will not rub against
painted surfaces during transport.
 The suspension should be com-
pressed somewhat by the tie-
downs, if possible, so that the mo-
torcycle will not bounce exces-
sively during transport.
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Instrument and control functions
3-15
3
EAU63040
ABSThe Yamaha ABS (Anti-lock Brake
System) features a dual electronic con-
trol system, which acts on the front and
rear brakes independently.
Operate the brakes with ABS as you
would conventional brakes. If the ABS
is activated, a pulsating sensation may
be felt at the brake lever or brake ped-
al. In this situation, continue to apply
the brakes and let the ABS work; do
not “pump” the brakes as this will re-
duce braking effectiveness.
WARNING
EWA16051
Always keep a sufficient d istance
from the vehicle ahea d to match the
ri din g speed even with ABS.
 The ABS performs best with
lon g b rakin g d istances.
 On certain surfaces, such as
rou gh or g ravel roa ds, the b rak-
in g d istance may b e longer with
the ABS than without.The ABS is monitored by an ECU,
which will revert the system to conven-
tional braking if a malfunction occurs.
TIP The ABS performs a self-diagno-
sis test each time the vehicle first
starts off after the key is turned to
“ON” and the vehicle has traveled
at a speed of 10 km/h (6 mi/h) or
higher. During this test, a “click-
ing” noise can be heard from the
hydraulic control unit, and if the
brake lever or brake pedal is even
slightly applied, a vibration can be
felt at the lever and pedal, but
these do not indicate a malfunc-
tion.
 This ABS has a test mode which
allows the owner to experience
the pulsation at the brake lever or
brake pedal when the ABS is op-
erating. However, special tools are
required, so please consult your
Yamaha dealer.NOTICE
ECA20100
Be careful not to damag e the wheel
sensor or wheel sensor rotor; other-
wise, improper performance of the
ABS will result.
1. Front wheel sensor rotor
2. Front wheel sensor
1. Rear wheel sensor
2. Rear wheel sensor rotorZAUM173412ZAUM1590
12
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Instrument and control functions
3-17
3
3. Wipe up any spilled fuel immedi-ately. NOTICE: Immediately
wipe off spille d fuel with a clean,
d ry, soft cloth, since fuel may
d eteriorate painted surfaces or
plastic parts.
[ECA10072]
4. Be sure to securely close the fuel tank cap.
WARNING
EWA15152
Gasoline is poisonous an d can
cause injury or death. Han dle gaso-
line with care. Never siphon gasoline
b y mouth. If you shoul d swallow
some gasoline or inhale a lot of gas-
oline vapor, or get some g asoline in
your eyes, see your doctor imme di- ately. If g
asoline spills on your skin,
wash with soap an d water. If gaso-
line spills on your clothin g, chan ge
your clothes.
EAU86072
Your Yamaha engine was designed to
use unleaded gasoline with a research
octane number of 95 or higher. If en-
gine knocking or pinging occurs, use a
gasoline of a different brand or higher
octane rating.
TIP This mark identifies the recom-
mended fuel for this vehicle as
specified by European regulation
(EN228).
 Confirm the gasoline pump nozzle
has the same fuel identification
mark.Gasohol
There are two types of gasohol: gaso-
hol containing ethanol and that con-
taining methanol. Gasohol containing
ethanol can be used if the ethanol con-
tent does not exceed 10% (E10). Gas-
ohol containing methanol is not
recommended by Yamaha because it
can cause damage to the fuel system
or vehicle performance problems.
1. Fuel tank filler tube
2. Maximum fuel level
1
2
Recommended fuel:
Unleaded gasoline (E10 acceptable)
Octane num ber (RON):
95
Fuel tank capacity: 10 L (2.6 US gal, 2.2 Imp.gal)
Fuel tank reserve:
3.0 L (0.79 US gal, 0.66 Imp.gal)
E5
E10
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Instrument and control functions
3-20
3
EAU14302
Helmet hol derThe helmet holder is located under the
seat.
To secure a helmet to the helmet
hol der
1. Open the seat. (See page 3-19.)
2. Attach the helmet to the helmet holder, and then securely close
the seat. WARNING! Never ri de
with a helmet attache d to the
helmet hol der, since the helmet
may hit o bjects, causin g loss of
control an d possi bly an acci-
d ent.
[EWA10162]
To release the helmet from the hel-
met hol der
Open the seat, remove the helmet from
the helmet holder, and then close the
seat.
EAU15306
Si destan dThe sidestand is located on the left
side of the frame. Raise the sidestand
or lower it with your foot while holding
the vehicle upright.TIPThe built-in sidestand switch is part of
the ignition circuit cut-off system,
which cuts the ignition in certain situa-
tions. (See the following section for an
explanation of the ignition circuit cut-
off system.)
WARNING
EWA10242
The vehicle must not be ri dden with
the si destan d d own, or if the si de-
stan d cannot b e properly move d up
(or does not stay up), otherwise the
si destan d coul d contact the groun d
an d d istract the operator, resultin g
in a possib le loss of control.
Yamaha’s ig nition circuit cut-off
system has been desi gne d to assist
the operator in fulfillin g the respon-
si bility of raisin g the sid estand b e-
fore startin g off. Therefore, check
1. Helmet holder
1
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Periodic maintenance an d a djustment
6-18
6
WARNING
EWA10472
 Have a Yamaha dealer replace
excessively worn tires. Besi des
b ein g ille gal, operatin g the vehi-
cle with excessively worn tires
d ecreases ri din g sta bility an d
can lead to loss of control.
 The replacement of all wheel
and b rake-relate d parts, inclu d-
in g the tires, shoul d b e left to a
Yamaha dealer, who has the
necessary professional knowl-
e dge an d experience to do so.
 Ride at mo derate spee ds after
chan gin g a tire since the tire
surface must first be “ broken
in” for it to develop its optimal
characteristics.
Tire information
This model is equipped with tubeless
tires and tire air valves.
Tires age, even if they have not been
used or have only been used occasion-
ally. Cracking of the tread and sidewall
rubber, sometimes accompanied by
carcass deformation, is an evidence of
ageing. Old and aged tires shall be
checked by tire specialists to ascertain
their suitability for further use.
WARNING
EWA16101
 The front an d rear tires shoul d
b e of the same make an d d e-
si gn, otherwise the han dlin g characteristics of the vehicle
may
be different, which coul d
lea d to an acci dent.
 Always make sure that the valve
caps are securely installe d to
prevent air pressure leaka ge.
 Use only the tire valves an d
valve cores liste d below to
avoi d tire d eflation during a ride.
After extensive tests, only the tires list-
ed below have been approved for this
model by Yamaha.
1. Tire air valve
2. Tire air valve core
3. Tire air valve cap with seal
12 3
Front tire:
Size:100/80-17M/C 52S
Manufacturer/model: MICHELIN PILOT STREET
Tire air valve:
TR412
Valve core: V3002 (original)
Rear tire: Size:140/70-17M/C 66S
Manufacturer/model: MICHELIN PILOT STREET
Tire air valve:
TR412
Valve core: V3002 (original)
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Periodic maintenance an d a djustment
6-26
6 may contain su
bstances that
coul d damag e the O-rin gs.
[ECA11112] EAU23098
Checkin
g an d lu bricatin g the
cab lesThe operation of all control cables and
the condition of the cables should be
checked before each ride, and the ca-
bles and cable ends should be lubri-
cated if necessary. If a cable is
damaged or does not move smoothly,
have a Yamaha dealer check or re-
place it. WARNING! Dama ge to the
outer housin g of cab les may result
in internal rustin g an d cause inter-
ference with cab le movement. Re-
place damag ed cab les as soon as
possi ble to prevent unsafe con di-
tions.
[EWA10712] EAU23115
Checkin
g an d lu bricatin g the
throttle grip an d ca bleThe operation of the throttle grip
should be checked before each ride. In
addition, the cable should be lubricat-
ed by a Yamaha dealer at the intervals
specified in the periodic maintenance
chart.
The throttle cable is equipped with a
rubber cover. Make sure that the cover
is securely installed. Even though the
cover is installed correctly, it does not
completely protect the cable from wa-
ter entry. Therefore, use care not to
pour water directly onto the cover or
cable when washing the vehicle. If the
cable or cover becomes dirty, wipe
clean with a moist cloth.
Recommen ded lu bricant:
Yamaha cable lubricant or other
suitable cable lubricant
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Periodic maintenance an d a djustment
6-29
6
EAU23273
Checkin g the front forkThe condition and operation of the
front fork must be checked as follows
at the intervals specified in the periodic
maintenance and lubrication chart.
To check the con dition
Check the inner tubes for scratches,
damage and excessive oil leakage.
To check the operation 1. Place the vehicle on a level sur- face and hold it in an upright posi-
tion. WARNING! To avoi d injury,
securely support the vehicle so
there is no dan ger of it fallin g
over.
[EWA10752]
2. While applying the front brake, push down hard on the handle-
bars several times to check if the
front fork compresses and re-
bounds smoothly.
NOTICE
ECA10591
If any damag e is foun d or the front
fork does not operate smoothly,
have a Yamaha d ealer check or re-
pair it.
EAU23285
Checkin g the steerin gWorn or loose steering bearings may
cause danger. Therefore, the operation
of the steering must be checked as fol-
lows at the intervals specified in the
periodic maintenance and lubrication
chart.
1. Raise the front wheel off the ground. (See page 6-34.)
WARNING! To avoi d injury, se-
curely support the vehicle so
there is no dan ger of it fallin g
over.
[EWA10752]
2. Hold the lower ends of the front fork legs and try to move them for-
ward and backward. If any free
play can be felt, have a Yamaha
dealer check or repair the steer-
ing.ZAUM1744
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Consumer information
9-2
9The model label is affixed to the frame
under the seat. (See page 3-19.) Re-
cord the information on this label in the
space provided. This information will
be needed when ordering spare parts
from a Yamaha dealer.
EAU69910
Dia
gnostic connectorThe diagnostic connector is located as
shown.
EAU85300
Vehicle data recor din gThis model’s ECU stores certain vehi-
cle data to assist in the diagnosis of
malfunctions and for research, statisti-
cal analysis and development purpos-
es.
Although the sensors and recorded
data will vary by model, the main data
points are:
 Vehicle status and engine perfor-
mance data
 Fuel-injection and emission-relat-
ed data
This data will be uploaded only when a
special Yamaha diagnostic tool is at-
tached to the vehicle, such as when
maintenance checks or service proce-
dures are performed.
Vehicle data uploaded will be handled
appropriately according to the follow-
ing Privacy Policy.
Privacy Policy
1. Diagnostic connector
1
https://www.yamaha-motor.eu/eu/
privacy/privacy-policy.aspx
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