YAMAHA MT-125 2021 Manual Online

Motorcycle care and stora ge
7-1
7
EAU37834
Matte color cautionNOTICE
ECA15193
Some mo dels are equipped with
matte colored finished parts. Be
sure to consult a Yamaha dealer for
a d vice on what prod ucts to use be-
fore cleanin g the vehicle. Usin g a
b rush, harsh chemical pro ducts or
cleanin g compoun ds when cleanin g
these parts will scratch or damag e
their surface. Wax also shoul d not
b e applie d to any matte colored fin-
ishe d parts.
EAU83443
CareFrequent, thorough cleaning of the ve-
hicle will not only enhance its appear-
ance but also will improve its general
performance and extend the useful life
of many components. Washing, clean-
ing, and polishing will also give you a
chance to inspect the condition of the
vehicle more frequently. Be sure to
wash the vehicle after riding in the rain
or near the sea, because salt is corro-
sive to metals.TIP The roads of heavy snowfall areas
may be sprayed with salt as a de-
icing method. This salt can stay on
the roads well into spring, so be
sure to wash the underside and
chassis parts after riding in such
areas.
 Genuine Yamaha care and main-
tenance products are sold under
the YAMALUBE brand in many
markets worldwide.
 See your Yamaha dealer for addi-
tional cleaning tips.
NOTICE
ECA26280
Improper cleanin g can cause cos-
metic an d mechanical damag e. Do
not use:  high-pressure washers or
steam-jet cleaners. Excessive
water pressure may cause wa-
ter seepag e and d eterioration of
wheel bearin gs, brakes, trans-
mission seals an d electrical de-
vices. Avoi d hi gh-pressure
d eter gent applications such as
those availa ble in coin-operate d
car washers.
 harsh chemicals, inclu din g
stron g aci dic wheel cleaners,
especially on spoke or ma gne-
sium wheels.
 harsh chemicals, a brasive
cleanin g compoun ds, or wax on
matte-finishe d parts. Brushes
can scratch an d damag e the
matte-finish, use soft spon ge or
towel only.
 towels, spon ges, or brushes
contaminate d with a brasive
cleanin g prod ucts or stron g
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Motorcycle care and stora ge
7-2
7 chemicals such as, solvents,
g
asoline, rust removers, brake
flui d, or antifreeze, etc.
Before washin g
1. Park the vehicle out of direct sun- light and allow it to cool. This will
help avoid water spots.
2. Make sure all caps, covers, elec- trical couplers and connectors are
tightly installed.
3. Cover the muffler end with a plas- tic bag and a strong rubber band.
4. Pre-soak stubborn stains like in- sects or bird droppings with a wet
towel for a few minutes.
5. Remove road grime and oil stains with a quality degreasing agent
and a plastic-bristle brush or
sponge. NOTICE: Do not use
d eg reasin g a gent on areas re-
quirin g lu brication such as
seals, gaskets, an d wheel axles.
Follow prod uct instructions.
[ECA26290]
Washing
1. Rinse off any degreaser and spray down the vehicle with a garden
hose. Use only enough pressure
to do the job. Avoid spraying wa-
ter directly into the muffler, instru-
ment panel, air inlet, or other inner
areas such as underseat storage
compartments.
2. Wash the vehicle with a quality au- tomotive-type detergent mixed
with cool water and a soft, clean
towel or sponge. Use an old tooth-
brush or plastic-bristle brush for
hard-to-reach places. NOTICE:
Use col d water if the vehicle has
b een exposed to salt. Warm wa-
ter will increase salt’s corrosive
properties.
[ECA26301]
3. For windshield-equipped vehicles: Clean the windshield with a soft
towel or sponge dampened with
water and a pH neutral detergent.
If necessary, use a high-quality
windshield cleaner or polish for
motorcycles. NOTICE: Never use
any stron g chemicals to clean
the win dshiel d. A dditionally,
some cleanin g compoun ds for plastic may scratch the win
d-
shiel d, so b e sure to test all
cleanin g prod ucts before gen-
eral application.
[ECA26310]
4. Rinse off thoroughly with clean water. Be sure to remove all deter-
gent residues, as they can be
harmful to plastic parts.
After washin g
1. Dry the vehicle with a chamois or absorbent towel, preferably mi-
crofiber terrycloth.
2. For drive chain-equipped models: Dry and then lubricate the drive
chain to prevent rust.
3. Use a chrome polish to shine chrome, aluminum, and stainless
steel parts. Often the thermally in-
duced discoloring of stainless
steel exhaust systems can be re-
moved through polishing.
4. Apply a corrosion protection spray on all metal parts including
chrome or nickel-plated surfaces.
WARNING! Do not apply sili-
cone or oil spray to seats, han d
g rips, ru bber foot peg s or tire
trea ds. Otherwise these parts
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Motorcycle care and stora ge
7-3
7
will
become slippery, which
coul d cause loss of control.
Thorou ghly clean the surfaces
of these parts before operatin g
the vehicle.
[EWA20650]
5. Treat rubber, vinyl, and unpainted plastic parts with a suitable care
product.
6. Touch up minor paint damage caused by stones, etc.
7. Wax all painted surfaces using a non-abrasive wax or use a detail
spray for motorcycles.
8. When finished cleaning, start the engine and let it idle for several
minutes to help dry any remaining
moisture.
9. If the headlight lens has fogged up, start the engine and turn on
the headlight to help remove the
moisture.
10. Let the vehicle dry completely be- fore storing or covering it.NOTICE
ECA26320
Do not apply wax to ru bber or
unpainte d plastic parts. 
Do not use a brasive polishin g
compoun ds as they will wear
away the paint.
 Apply sprays an d wax sparin gly.
Wipe off excess afterwar ds.
WARNING
EWA20660
Contaminants left on the brakes or
tires can cause loss of control.  Make sure there is no lu bricant
or wax on the brakes or tires.
 If necessary, wash the tires with
warm water an d a mil d d eter-
g ent.
 If necessary, clean the b rake
d iscs an d pa ds with b rake
cleaner or acetone.
 Before ri din g at hi gher spee ds,
test the vehicle’s brakin g per-
formance an d cornerin g b ehav-
ior.
EAU83472
Stora geAlways store the vehicle in a cool, dry
place. If necessary, protect it against
dust with a porous cover. Be sure the
engine and the exhaust system are
cool before covering the vehicle. If the
vehicle often sits for weeks at a time
between uses, the use of a quality fuel
stabilizer is recommended after each
fill-up.NOTICE
ECA21170
 Storin g the vehicle in a poorly
ventilate d room or coverin g it
with a tarp, while it is still wet,
will allow water an d humi dity to
seep in an d cause rust.
 To prevent corrosion, avoi d
d amp cellars, stab les (because
of the presence of ammonia)
an d areas where stron g chemi-
cals are stored .Long term stora ge
Before storing the vehicle long term (60
days or more):
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Motorcycle care and stora ge
7-4
7 1. Make all necessary repairs and
perform any outstanding mainte-
nance.
2. Follow all instructions in the Care section of this chapter.
3. Fill up the fuel tank, adding fuel stabilizer according to product in-
structions. Run the engine for 5
minutes to distribute treated fuel
through the fuel system.
4. For vehicles equipped with a fuel cock: Turn the fuel cock lever to
the off position.
5. For vehicles with a carburetor: To prevent fuel deposits from build-
ing up, drain the fuel in the carbu-
retor float chamber into a clean
container. Retighten the drain bolt
and pour the fuel back into the fuel
tank.
6. Use a quality engine fogging oil according to product instructions
to protect internal engine compo-
nents from corrosion. If engine
fogging oil is not available, per-
form the following steps for each
cylinder:a. Remove the spark plug cap and spark plug. b. Pour a teaspoonful of engine
oil into the spark plug bore.
c. Install the spark plug cap onto the spark plug, and then place
the spark plug on the cylinder
head so that the electrodes are
grounded. (This will limit spark-
ing during the next step.)
d. Turn the engine over several times with the starter. (This will
coat the cylinder wall with oil.)
WARNING! To prevent d am-
a g e or injury from sparkin g,
make sure to groun d the
spark plu g electro des while
turnin g the en gine over.
[EWA10952]
e. Remove the spark plug cap
from the spark plug, and then
install the spark plug and the
spark plug cap.
7. Lubricate all control cables, piv- ots, levers and pedals, as well as
the sidestand and centerstand (if
equipped).
8. Check and correct the tire air pressure, and then lift the vehicle
so that all wheels are off the
ground. Otherwise, turn the wheels a little once a month in or-
der to prevent the tires from be-
coming degraded in one spot.
9. Cover the muffler outlet with a plastic bag to prevent moisture
from entering it.
10. Remove the battery and fully charge it, or attach a maintenance
charger to keep the battery opti-
mally charged. NOTICE: Confirm
that the battery an d its char ger
are compati ble. Do not char ge a
VRLA battery with a convention-
al char ger.
[ECA26330]
TIP If the battery will be removed,
charge it once a month and store
it in a temperate location between
0-30 °C (32-90 °F).
 See page 6-30 for more informa-
tion on charging and storing the
battery.
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Specifications
8-1
8
Dimensions:Overall length:1960 mm (77.2 in)
Overall width:
800 mm (31.5 in)
Overall height: 1065 mm (41.9 in)
Seat height: 810 mm (31.9 in)
Wheelbase:
1325 mm (52.2 in)
Ground clearance: 160 mm (6.30 in)
Minimum turning radius: 2.9 m (9.51 ft)Wei ght:Curb weight:
142 kg (313 lb)Engine:Combustion cycle:
4-stroke
Cooling system: Liquid cooled
Valve train: SOHC
Number of cylinders:
Single cylinder
Displacement: 124 cm³
Bore × stroke:
52.0 × 58.6 mm (2.05 × 2.31 in)
Starting system:
Electric starter
Engine oil:Recommended brand:
SAE viscosity grades:
10W-40
Recommended engine oil grade: API service SG type or higher, JASO
standard MA
Engine oil quantity: Oil change:0.85 L (0.90 US qt, 0.75 Imp.qt)
With oil filter removal: 0.95 L (1.00 US qt, 0.84 Imp.qt)Coolant quantity:Coolant reservoir (up to the maximum level
mark):
0.15 L (0.16 US qt, 0.13 Imp.qt)
Radiator (including all routes): 0.49 L (0.52 US qt, 0.43 Imp.qt)Fuel:Recommended fuel:
Unleaded gasoline (E10 acceptable)
Octane number (RON): 95
Fuel tank capacity: 10 L (2.6 US gal, 2.2 Imp.gal)
Fuel reserve amount:
3.0 L (0.79 US gal, 0.66 Imp.gal)
Fuel injection:Throttle body:ID mark:BK71 00Drivetrain:Gear ratio:
1st: 2.833 (34/12)
2nd:
1.875 (30/16)
3rd: 1.364 (30/22)
4th: 1.143 (24/21)
5th:
0.957 (22/23)
6th: 0.840 (21/25)Front tire:Type:
Tubeless
Size: 100/80-17M/C 52S
Manufacturer/model: MICHELIN PILOT STREETRear tire:Type:Tubeless
Size: 140/70-17M/C 66S
Manufacturer/model:
MICHELIN PILOT STREET
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Specifications
8-2
8
Loadin g:Maximum load:
178 kg (392 lb)
(Total weight of rider, passenger, cargo and
accessories)Front brake:Type:
Hydraulic single disc brakeRear brake:Type:
Hydraulic single disc brakeFront suspension:Type:
Telescopic forkRear suspension:Type:Swingarm (link suspension)Electrical system:System voltage:12 VBattery:Model:
GTZ4V
Voltage, capacity: 12 V, 3.0 Ah (10 HR)Bul b watta ge:Headlight:
LED
Brake/tail light: LED
Front turn signal light: 10.0 W
Rear turn signal light:
10.0 W Auxiliary light:
LED
License plate light: 5.0 W
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Consumer information
9-1
9
EAU53562
Id entification num bersRecord the vehicle identification num-
ber, engine serial number, and the
model label information in the spaces
provided below. These identification
numbers are needed when registering
the vehicle with the authorities in your
area and when ordering spare parts
from a Yamaha dealer.
VEHICLE IDENTIFICATION NUMBER:
ENGINE SERIAL NUMBER:
MODEL LABEL INFORMATION:
EAU26401
Vehicle i dentification num ber
The vehicle identification number is
stamped into the steering head pipe.
Record this number in the space pro-
vided.TIPThe vehicle identification number is
used to identify your motorcycle and
may be used to register your motorcy-
cle with the licensing authority in your
area.
EAU26442
En gine serial num ber
The engine serial number is stamped
into the crankcase.
EAU26481
Mo del la bel
1. Vehicle identification number
1
1. Engine serial number
1. Model label
1
1
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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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Consumer information
9-3
9
Yamaha will not disclose this data to a
third party except in the following cas-
es. In addition, Yamaha may provide
vehicle data to a contractor in order to
outsource services related to the han-
dling of vehicle data. Even in this case,
Yamaha will require the contractor to properly handle the vehicle data we
provided and Yamaha will appropriate-
ly manage the data.  With the consent of the vehicle
owner
 Where obligated by law
 For use by Yamaha in litigation
 When the data is not related to an
individual vehicle nor owner
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10-1
10
IndexAABS ....................................................... 3-15
ABS warning light ................................... 3-3
Air filter element and check hose,
replacing and cleaning ....................... 6-14BBattery .................................................. 6-30
Brake and clutch levers, checking and lubricating ........................................... 6-27
Brake and shift pedals, checking and lubricating ........................................... 6-27
Brake fluid, changing ............................ 6-24
Brake fluid level, checking .................... 6-22
Brake lever ............................................ 3-14
Brake light switches.............................. 6-21
Brake pedal........................................... 3-14
Brake pedal free play, adjusting ........... 6-21CCables, checking and lubricating ......... 6-26
Canister................................................... 6-9
Care ........................................................ 7-1
Catalytic converter ................................ 3-19
Clutch lever ........................................... 3-13
Clutch lever free play, adjusting ........... 6-19
Coolant ................................................. 6-13
Coolant temperature warning light ......... 3-2
Cowlings, removing and installing .......... 6-8DData recording, vehicle ........................... 9-2
Diagnostic connector.............................. 9-2
Dimmer switch ...................................... 3-13
Drive chain, cleaning and lubricating .... 6-25
Drive chain slack................................... 6-24
EEngine break-in ...................................... 5-1
Engine idling speed .............................. 6-15
Engine oil and oil filter element ............ 6-10
Engine overheating ............................... 6-36
Engine serial number .............................. 9-1FFront and rear brake pads, checking ... 6-22
Front brake lever free play, checking ... 6-20
Front fork, checking ............................. 6-29
Fuel ....................................................... 3-16
Fuel consumption, tips for reducing ...... 5-4
Fuel tank breather hose and overflow hose ................................................... 3-18
Fuel tank cap ........................................ 3-16
Fuses, replacing ................................... 6-31HHandlebar switches .............................. 3-12
Helmet holder ....................................... 3-20
High beam indicator light ....................... 3-2
Horn switch .......................................... 3-13IIdentification numbers ............................ 9-1
Ignition circuit cut-off system ............... 3-21
Indicator lights and warning lights ......... 3-2LLicense plate light bulb, replacing........ 6-33MMain switch/steering lock....................... 3-1
Maintenance and lubrication, periodic ... 6-4
Maintenance, emission control system.................................................. 6-3
Malfunction indicator light (MIL) ............. 3-3
Matte color, caution ............................... 7-1 Model label .............................................9-1
Multi-function meter unit .........................3-4
NNeutral indicator light ..............................3-2PParking ....................................................5-4
Part locations ..........................................2-1
Pass switch ...........................................3-13RRear suspension, lubricating ................6-28SSafety information ...................................1-1
Seat .......................................................3-19
Shifting ....................................................5-3
Shift light .................................................3-3
Shift pedal .............................................3-14
Sidestand ..............................................3-20
Sidestand, checking and lubricating.....6-28
Spark plug, checking ..............................6-8
Specifications .........................................8-1
Start/Engine stop switch .......................3-13
Starting the engine ..................................5-2
Steering, checking ................................6-29
Storage ...................................................7-3
Supporting the motorcycle ...................6-34TTail/brake light ......................................6-32
Throttle grip and cable, checking and
lubricating ...........................................6-26
Throttle grip free play, adjusting ...........6-16
Tires ......................................................6-17
Tool kit ....................................................6-2
Troubleshooting ....................................6-34
Troubleshooting chart ...........................6-35
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