2021 YAMAHA MT-125 radiator

Instrument and control functions
3-2
3
To unlock the steering
From the “LOCK” position, push the
key and turn it to “OFF”.
EAU4939N
In
dicator li ghts an d warnin g
lig hts
EAU11022
Turn si gnal in dicator li ght “ ”
This indicator light flashes when a turn
signal light is flashing.
EAU11061
Neutral in dicator li ght “ ”
This indicator light comes on when the
transmission is in the neutral position.
EAU11081
Hi gh beam in dicator li ght “ ”
This indicator light comes on when the
high beam of the headlight is switched
on.
EAU11449
Coolant temperature warnin g
li g ht “ ”
This warning light comes on when the
engine is overheating. If this occurs,
stop the engine immediately and allow
the engine to cool. (See page 6-36.)
For vehicles with a radiator fan, the ra-
diator fan(s) automatically switch on or
off according to the coolant tempera-
ture.TIPWhen the vehicle is turned on, the light
will come on for a few seconds, and
then go off. If the light does not come
on, or if the light remains on, have a
Yamaha dealer check the vehicle. NOTICE
ECA10022
Do not continue to operate the en-
g ine if it is overheatin g.
1. Push.
2. Turn.12
1. Shift light
2. Turn signal indicator light “ ”
3. High beam indicator light “ ”
4. Anti-lock Brake System (ABS) warning
light “ ”
5. Malfunction indicator light “ ”
6. Coolant temperature warning light “ ”
7. Neutral indicator light “ ”ZAUM15665 6 7
2
3
4
1
ABS
UB6GE1E0.book Page 2 Thursday, July 30, 2020 1:08 PM

Periodic maintenance an d a djustment
6-13
6
EAUS1203
CoolantThe coolant level should be checked
regularly. In addition, the coolant must
be changed at the intervals specified in
the periodic maintenance chart.TIPIf genuine Yamaha coolant is not avail-
able, use an ethylene glycol antifreeze
containing corrosion inhibitors for alu-
minum engines and mix with distilled
water at a 1:1 ratio.
EAUE4091
To check the coolant level
1. Place the vehicle on a level sur- face.
2. Remove cowling A. (See page 6-8.)
3. Hold the vehicle in an upright po- sition.
TIPThe coolant level must be
checked on a cold engine since
the level varies with engine tem-
perature.
 Make sure that the vehicle is posi-
tioned straight up when checking
the coolant level. A slight tilt to the
side can result in a false reading.4. Check the coolant level in the
coolant reservoir.TIPThe coolant should be between the
minimum and maximum level marks.
5. If the coolant is at or below theminimum level mark, remove the
coolant reservoir cap protector by
removing the bolt then remove the
coolant reservoir cap.
Recommen ded coolant:
YAMALUBE coolant
Coolant quantity: Coolant reservoir (max 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)
1. Coolant reservoir
2. Maximum level mark
3. Minimum level mark
1. Coolant reservoir cap protector
1. Coolant reservoir cap
UB6GE1E0.book Page 13 Thursday, July 30, 2020 1:08 PM

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.
UB6GE1E0.book Page 36 Thursday, July 30, 2020 1:08 PM

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