YAMAHA MT-125 2021 Owner's Guide

Instrument and control functions
3-16
3
EAU13077
Fuel tank capTo open the fuel tank cap
Open the fuel tank cap lock cover, in-
sert the key, and then turn it 1/4 turn
clockwise. The lock will be released
and the fuel tank cap can be opened.
To close the fuel tank cap
With the key still inserted, push down
the fuel tank cap. Turn the key 1/4 turn
counterclockwise, remove it, and then
close the lock cover.
TIPThe fuel tank cap cannot be closed un-
less the key is in the lock. In addition,
the key cannot be removed if the cap is
not properly closed and locked.
WARNING
EWA11092
Make sure that the fuel tank cap is
properly close d after fillin g fuel.
Leakin g fuel is a fire hazar d.
EAU13222
FuelMake sure there is sufficient gasoline in
the tank.
WARNING
EWA10882
Gasoline an d gasoline vapors are
extremely flammab le. To avoid fires
an d explosions an d to re duce the
risk of injury when refuelin g, follow
these instructions.1. Before refueling, turn off the en- gine and be sure that no one is sit-
ting on the vehicle. Never refuel
while smoking, or while in the vi-
cinity of sparks, open flames, or
other sources of ignition such as
the pilot lights of water heaters
and clothes dryers.
2. Do not overfill the fuel tank. When refueling, be sure to insert the
pump nozzle into the fuel tank filler
hole. Stop filling when the fuel
reaches the bottom of the filler
tube. Because fuel expands when
it heats up, heat from the engine or
the sun can cause fuel to spill out
of the fuel tank.
1. Fuel tank cap lock cover
2. Unlock.
1
2
UB6GE1E0.book Page 16 Thursday, July 30, 2020 1:08 PM

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
UB6GE1E0.book Page 17 Thursday, July 30, 2020 1:08 PM

Instrument and control functions
3-18
3
NOTICE
ECA11401
Use only unlea ded g asoline. The use
of lead ed g asoline will cause severe
d amag e to internal en gine parts,
such as the valves an d piston rin gs,
as well as to the exhaust system.
EAU86240
Fuel tank breather hose an d
overflow hoseThe breather hose prevents a vacuum
condition from forming within the fuel
tank.
The overflow hose drains excess gaso-
line and directs it safely away from the
vehicle.
Before operating the vehicle:
 Check each hose connection.
 Check each hose for cracks or
damage, and replace if necessary.
 Make sure that the end of each
hose is not blocked, and clean if
necessary. 
Make sure that each hose is posi-
tioned as shown.1. Guide
2. Fuel tank overflow hose
3. Canister breather hoseZAUM1801
1
32
UB6GE1E0.book Page 18 Thursday, July 30, 2020 1:08 PM

Instrument and control functions
3-19
3
EAU13435
Catalytic converterThe exhaust system contains catalytic
converter(s) to reduce harmful exhaust
emissions.
WARNING
EWA10863
The exhaust system is hot after op-
eration. To prevent a fire hazar d or
b urns:
 Do not park the vehicle near
possi ble fire hazard s such as
g rass or other materials that
easily burn.
 Park the vehicle in a place
where ped estrians or chil dren
are not likely to touch the hot
exhaust system.
 Make sure that the exhaust sys-
tem has cooled down before
d oin g any maintenance work.
 Do not allow the en gine to i dle
more than a few minutes. Lon g
i d lin g can cause a b uild-up of
heat.
EAU57992
SeatTo remove the seat 1. Open the seat lock cover, insert the key into the seat lock, and then
turn the key counterclockwise.
2. While holding the key in that posi- tion, slide the seat backward and
then lift the rear of the seat up, and
then pull the seat off.
To install the seat 1. Insert the projections into the seat holders as shown. 2. Push the rear of the seat down to
lock it in place.
3. Remove the key.
TIPMake sure that the seat is properly se-
cured before riding.
1. Seat lock cover
2. Seat lock
3. Turn.
1 2 3
UB6GE1E0.book Page 19 Thursday, July 30, 2020 1:08 PM

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
UB6GE1E0.book Page 20 Thursday, July 30, 2020 1:08 PM

Instrument and control functions
3-21
3 this system reg
ularly and have a
Yamaha dealer repair it if it does not
function properly.
EAU44895
I g nition circuit cut-off systemThis system prevents in-gear engine
starts unless the clutch lever is pulled
and the sidestand is up. Also, it will
stop the running engine should the
sidestand be lowered while the trans-
mission is in gear.
Periodically check the system via the
following procedure.TIP This check is most reliable if per-
formed with a warmed-up engine.
 See pages 3-1 and 3-12 for switch
operation information.
UB6GE1E0.book Page 21 Thursday, July 30, 2020 1:08 PM

Instrument and control functions
3-22
3
With the engine turned off:
1. Move the sidestand down.
2. Set engine stop switch to run position.
3. Turn main switch to on position.
4. Shift transmission into neutral.
5. Push the start switch.
Does the engine start?
With the engine still running:
6. Move the sidestand up.
7. Pull the clutch lever.
8. Shift transmission into gear.
9. Move the sidestand down.
Does the engine stall?
After the engine has stalled:
10. Move the sidestand up.
11. Pull the clutch lever.
12. Push the start switch.
Does the engine start?
The system is OK. The motorcycle can be ridden.
YES NO YES NO YES NO
The neutral switch may not be working.
The motorcycle should not be ridden until
checked by a Yamaha dealer.
The clutch switch may not be working.
The motorcycle should not be ridden until
checked by a Yamaha dealer.The sidestand switch may not be working.
The motorcycle should not be ridden until
checked by a Yamaha dealer.If a malfunction is found, have the vehicle
inspected before riding.
WARNING
UB6GE1E0.book Page 22 Thursday, July 30, 2020 1:08 PM

For your safety – pre-operation checks
4-1
4
EAU1559B
Inspect your vehicle each time you use it to make sure the vehicle is in safe operating condition. Always follow the inspection
and maintenance procedures and schedules described in the Owner’s Manual.
WARNING
EWA11152
Failure to inspect or maintain the vehicle properly increases the possibility of an acci dent or equipment damag e.
Do not operate the vehicle if you fin d any pro blem. If a pro blem cannot be corrected b y the proce dures provi ded in
this manual, have the vehicle inspecte d b y a Yamaha dealer.Before using this vehicle, check the following points:
ITEM CHECKS PAGE
Fuel • Check fuel level in fuel tank.
• Refuel if necessary.
• Check fuel line for leakage.
• Check fuel tank breather hose and overflow hose for obstructions, cracks or
damage, and check hose connections. 3-16, 3-18
En gine oil • Check oil level in engine.
• If necessary, add recommended oil to specified level.
• Check vehicle for oil leakage. 6-10
Coolant • Check coolant level in reservoir.
• If necessary, add recommended coolant to specified level.
• Check cooling system for leakage. 6-13
Front brake • Check operation.
• If soft or spongy, have Yamaha dealer bleed hydraulic system.
• Check brake pads for wear.
• Replace if necessary.
• Check fluid level in reservoir.
• If necessary, add specified brake fluid to specified level.
• Check hydraulic system for leakage. 6-22, 6-22
UB6GE1E0.book Page 1 Thursday, July 30, 2020 1:08 PM

For your safety – pre-operation checks
4-2
4
Rear brake • Check operation.
• If soft or spongy, have Yamaha dealer bleed hydraulic system.
• Check brake pads for wear.
• Replace if necessary.
• Check fluid level in reservoir.
• If necessary, add specified brake fluid to specified level.
• Check hydraulic system for leakage. 6-22, 6-22
Clutch • Check operation.
• Lubricate cable if necessary.
• Check lever free play.
• Adjust if necessary.
6-19
Throttle grip • Make sure that operation is smooth.
• Check throttle grip free play.
• If necessary, have Yamaha dealer adjust throttle grip free play and lubricate ca-
ble and grip housing. 6-16, 6-26
Control ca bles • Make sure that operation is smooth.
• Lubricate if necessary. 6-26
Drive chain • Check chain slack.
• Adjust if necessary.
• Check chain condition.
• Lubricate if necessary.
6-24, 6-25
Wheels an d tires • Check for damage.
• Check tire condition and tread depth.
• Check air pressure.
• Correct if necessary.
6-17, 6-19
Brake an d shift pe dals • Make sure that operation is smooth.
• Lubricate pedal pivoting points if necessary. 6-27
Brake an d clutch levers • Make sure that operation is smooth.
• Lubricate lever pivoting points if necessary.
6-27
Si destan d • Make sure that operation is smooth.
• Lubricate pivot if necessary.
6-28
ITEM CHECKS PAGE
UB6GE1E0.book Page 2 Thursday, July 30, 2020 1:08 PM

For your safety – pre-operation checks
4-3
4
Chassis fasteners• Make sure that all nuts, bolts and screws are properly tightened.
• Tighten if necessary. —
Instruments, li ghts, si gnals
an d switches • Check operation.
• Correct if necessary.
—
Si destan d switch • Check operation of ignition circuit cut-off system.
• If system is not working correctly, have Yamaha dealer check vehicle. 3-20
ITEM CHECKS PAGE
UB6GE1E0.book Page 3 Thursday, July 30, 2020 1:08 PM