2020 YAMAHA MT-125 coolant

Periodic maintenance and adjustment
6-37
6
EAU86430Engine overheating
WARNING
EWAT1041
Do not remove the radiator cap when the engine and radiator are hot.
Scalding hot fluid and steam may be blown out under pressure, which
could cause serious injury. Be sure to wait until the engine has cooled.
Place a thick rag, like a towel, over the radiator cap, and then slowly ro-
tate the cap counterclockwise to the detent to allow any residual pres-
sure to escape. When the hissing sound has stopped, press down on the
cap while turning it counterclockwise, and then remove the cap.
TIP
If coolant is not available, tap water can be temporarily used instead, provided
that it is changed to the recommended coolant as soon as possible.
Wait until the engine
has cooled.
Check the coolant
level in the reservoir
and radiator.Add coolant.
(See TIP.)
The coolant level is
OK.
There is no leakage.
There is leakage.
The coolant level is
low.
Check the cooling
system for leakage.
Have a Yamaha
dealer check and
repair the cooling
system.
Start the engine. If the engine overheats again,
have a Yamaha dealer check and repair the cooling
system.
UB6GE0E0.book Page 37 Wednesday, August 28, 2019 11:11 AM

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)
Weight:
Curb weight:
140 kg (309 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:
B5G1 00
Drivetrain:
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 STREET
Rear tire:
Type:
Tubeless
Size:
140/70-17M/C 66S
Manufacturer/model:
MICHELIN PILOT STREET
Loading:
Maximum load:
180 kg (397 lb)
UB6GE0E0.book Page 1 Wednesday, August 28, 2019 11:11 AM

10-1
10
Index
A
ABS ....................................................... 3-15
ABS warning light ................................... 3-3
Air filter element and check hose,
replacing and cleaning ....................... 6-13
B
Battery .................................................. 6-30
Brake and clutch levers, checking and
lubricating ........................................... 6-27
Brake and shift pedals, checking and
lubricating ........................................... 6-26
Brake fluid, changing ............................ 6-23
Brake fluid level, checking .................... 6-22
Brake lever ............................................ 3-14
Brake light switches.............................. 6-20
Brake pedal........................................... 3-14
Brake pedal free play, adjusting ........... 6-20
C
Cables, checking and lubricating ......... 6-25
Care ........................................................ 7-1
Catalytic converter ................................ 3-18
Clutch lever ........................................... 3-13
Clutch lever free play, adjusting ........... 6-18
Coolant ................................................. 6-11
Coolant temperature warning light ......... 3-2
Cowlings, removing and installing .......... 6-7
D
Data recording, vehicle ........................... 9-3
Diagnostic connectors ............................ 9-2
Dimmer switch ...................................... 3-12
Drive chain, cleaning and lubricating .... 6-25
Drive chain slack................................... 6-23
E
Engine break-in....................................... 5-1
Engine idling speed .............................. 6-13
Engine oil and oil filter element ............... 6-8
Engine overheating ............................... 6-37
Engine serial number .............................. 9-1
Engine trouble warning light ................... 3-3
F
Front and rear brake pads, checking.... 6-21
Front brake lever free play, checking ... 6-19
Front fork, checking .............................. 6-28
Fuel ....................................................... 3-16
Fuel consumption, tips for reducing ....... 5-5
Fuel tank cap ........................................ 3-16
Fuel tank overflow hose ........................ 3-18
Fuses, replacing.................................... 6-31
H
Handlebar switches .............................. 3-12Helmet holder ....................................... 3-20
High beam indicator light ....................... 3-2
Horn switch .......................................... 3-12
I
Identification numbers ............................ 9-1
Ignition circuit cut-off system............... 3-21
Indicator lights and warning lights ......... 3-2
L
License plate light bulb, replacing........ 6-34
M
Main switch/steering lock....................... 3-1
Maintenance and lubrication, periodic ... 6-4
Maintenance, emission control
system.................................................. 6-3
Matte color, caution ............................... 7-1
Model label ............................................. 9-1
Multi-function meter unit ........................ 3-4
N
Neutral indicator light ............................. 3-2
P
Parking ................................................... 5-6
Part locations ......................................... 2-1
Pass switch .......................................... 3-12
S
Safety information .................................. 1-1
Seat ...................................................... 3-19
Shifting ................................................... 5-4
Shift light ................................................ 3-3
Shift pedal ............................................ 3-13
Sidestand ............................................. 3-20
Sidestand, checking and lubricating .... 6-27
Spark plug, checking ............................. 6-7
Specifications ......................................... 8-1
Start/Engine stop switch ...................... 3-12
Starting the engine ................................. 5-2
Steering, checking................................ 6-29
Storage ................................................... 7-4
Supporting the motorcycle................... 6-34
Swingarm pivots, lubricating ................ 6-28
T
Tail/brake light ...................................... 6-33
Throttle grip and cable, checking and
lubricating .......................................... 6-26
Throttle grip free play, adjusting........... 6-14
Tires ...................................................... 6-15
Tool kit.................................................... 6-2
Troubleshooting ................................... 6-35
Troubleshooting chart .......................... 6-36
Turn signal indicator light ....................... 3-2
Turn signal light bulb, replacing ........... 6-33
UB6GE0E0.book Page 1 Wednesday, August 28, 2019 11:11 AM