warning YAMAHA MT-125 2021 Owner's Guide

Periodic maintenance an d a djustment
6-31
6
To char
ge the b attery
Have your Yamaha dealer charge the
battery if it seems to have discharged.
Keep in mind that the battery tends to
discharge more quickly if the vehicle is
equipped with optional electrical ac-
cessories.
NOTICE
ECA16522
To char ge a VRLA (Valve Re gulate d
Lea d Aci d) battery, a special (con-
stant-volta ge) battery char ger is re-
quire d. Usin g a conventional b attery
char ger will damag e the battery.To store the battery
1. If the vehicle will not be used for more than one month, remove the
battery, fully charge it, and then
place it in a cool, dry place.
NOTICE: When removin g the
b attery, be sure to turn the main
switch off, then disconnect the
ne gative lead before discon-
nectin g the positive lea d.
[ECA16304]
2. If the battery will be stored for
more than two months, check it at
least once a month and fully
charge it if necessary. 3. Fully charge the battery before in-
stallation. NOTICE: When install-
in g the b attery, be sure to turn
the main switch off, then con-
nect the positive lea d before
connectin g the ne gative lea d.
[ECA16842]
4. After installation, make sure that
the battery leads are properly con-
nected to the battery terminals.NOTICE
ECA16531
Always keep the b attery charged .
Storin g a dischar ged battery can
cause permanent b attery damag e.
EAUB1116
Replacin g the fusesThe fuse box is located under the seat.
(See page 3-19.)
If a fuse is blown, replace it as follows.
1. Turn the main switch off and turn off the electrical circuit in ques-
tion.
2. Remove the blown fuse, and then install a new fuse of the specified
amperage. WARNING! Do not
use a fuse of a hi gher ampera ge1. Fuse box
2. Spare fuse
3. Headlight fuse
4. ABS control unit fuse
5. Main fuse
6. ABS solenoid fuse
7. ABS motor fuse
8. Fuse tongs
15
7.5
2
1
5
7
.5
1
5
3
0
30
2
1
8
76
543
2
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Periodic maintenance an d a djustment
6-34
6
EAU67131
Supportin g the motorcycleSince this model is not equipped with a
centerstand, use maintenance stands
when removing the front or rear wheel
or when performing other maintenance
that requires the motorcycle to stand
up right.
Check that the motorcycle is in a stable
and level position before starting any
maintenance.
EAU25872
Trou bleshootin gAlthough Yamaha motorcycles receive
a thorough inspection before shipment
from the factory, trouble may occur
during operation. Any problem in the
fuel, compression, or ignition systems,
for example, can cause poor starting
and loss of power.
The following troubleshooting charts
represent quick and easy procedures
for checking these vital systems your-
self. However, should your motorcycle
require any repair, take it to a Yamaha
dealer, whose skilled technicians have
the necessary tools, experience, and
know-how to service the motorcycle
properly.
Use only genuine Yamaha replace-
ment parts. Imitation parts may look
like Yamaha parts, but they are often
inferior, have a shorter service life and
can lead to expensive repair bills.
WARNING
EWA15142
When checkin g the fuel system, do
not smoke, an d make sure there are
no open flames or sparks in the ar-
ea, inclu din g pilot lig hts from water heaters or furnaces. Gasoline or
g
asoline vapors can i gnite or ex-
plod e, causin g severe injury or prop-
erty damag e.
1. Maintenance stand (example)
1
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Periodic maintenance an d a djustment
6-36
6
EAU86420
En gine overheatin g
WARNING
EWAT1041
Do not remove the ra diator cap when the en gine an d ra diator are hot. Scal din g hot flui d an d steam may be
b lown out un der pressure, which coul d cause serious injury. Be sure to wait until the en gine has coole d.
 Place a thick ra g, like a towel, over the ra diator cap, an d then slowly rotate the cap counterclockwise to the
d etent to allow any resi dual pressure to escape. When the hissin g soun d has stoppe d, press d own on the cap
while turnin g it counterclockwise, an d then remove the cap.TIPIf coolant is not available, tap water can be temporarily used instead, provided that it is changed to the recommended cool-
ant as soon as possible.
Wait until the
engine has cooled.
Check the coolant level in the
reservoir and radiator.
The coolant level
is OK.The coolant level is low.
Check the cooling system
for leakage.
Have a Yamaha dealer checkand repair the cooling system.Add coolant. (See TIP.)
Start the engine. If the engine overheats again,
have a
Yamaha dealer check
and repair the cooling system.
There is
leakage.
There is
no leakage.
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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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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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