2021 YAMAHA MT-125 service

Periodic maintenance an d a djustment
6-1
6
EAU17246
Periodic inspection, adjustment, and
lubrication will keep your vehicle in the
safest and most efficient condition
possible. Safety is an obligation of the
vehicle owner/operator. The most im-
portant points of vehicle inspection,
adjustment, and lubrication are ex-
plained on the following pages.
The intervals given in the periodic
maintenance charts should be simply
considered as a general guide under
normal riding conditions. However, de-
pending on the weather, terrain, geo-
graphical location, and individual use,
the maintenance intervals may need to
be shortened.
WARNING
EWA10322
Failure to properly maintain the vehi-
cle or performin g maintenance ac-
tivities incorrectly may increase
your risk of injury or death during
service or while usin g the vehicle. If
you are not familiar with vehicle ser-
vice, have a Yamaha d ealer perform
service.
WARNING
EWA15123
Turn off the en gine when performin g
maintenance unless otherwise
specified .
 A runnin g en gine has movin g
parts that can catch on b ody
parts or clothin g an d electrical
parts that can cause shocks or
fires.
 Runnin g the eng ine while ser-
vicin g can lead to eye injury,
b urns, fire, or car bon monoxi de
poisonin g – possi bly lea din g to
d eath. See pag e 1-3 for more in-
formation a bout car bon monox-
i d e.
WARNING
EWA15461
Brake discs, calipers, drums, an d
linin gs can b ecome very hot during
use. To avoi d possi ble burns, let
b rake components cool before
touching them.
EAU17303
Emission controls not only function to
ensure cleaner air, but are also vital to
proper engine operation and maximum
performance. In the following periodic
maintenance charts, the services relat-
ed to emissions control are grouped
separately. These services require
specialized data, knowledge, and
equipment. Maintenance, replace-
ment, or repair of the emission control
devices and systems may be per-
formed by any repair establishment or
individual that is certified (if applicable).
Yamaha dealers are trained and
equipped to perform these particular
services.
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Periodic maintenance an d a djustment
6-7
6
EAU72750
TIP The air filter needs more frequent service if you are riding in unusually wet or dusty areas.
 Hydraulic brake service
• Regularly check and, if necessary, correct the brake fluid level.
• Every two years replace the internal components of the brake master cylinders and calipers, and change the brake fluid.
• Replace the brake hoses every four years and if cracked or damaged.30 *Throttle g
rip hous-
in g an d ca ble • Check operation and free play.
• Adjust the throttle cable free play
if necessary.
• Lubricate the throttle grip housing and cable. √√√√√
31 *Li
ghts, si gnals an d
switches • Check operation.
• Adjust headlight beam.
√√√√√√
NO. ITEM CHECK OR MAINTENANCE JOB
ODOMETER READING
ANNUAL
CHECK
1000 km
(600 mi) 6000 km
(3500 mi) 12000 km
(7000 mi) 18000 km
(10500 mi) 24000 km
(14000 mi)
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Periodic maintenance an d a djustment
6-16
6
EAU48434
A djustin g the throttle grip free
playMeasure the throttle grip free play as
shown.
Periodically check the throttle grip free
play and, if necessary, adjust it as fol-
lows.TIPThe engine idling speed must be cor-
rectly adjusted before checking and
adjusting the throttle grip free play.1. Slide the rubber cover back.
2. Loosen the locknut. 3. To increase the throttle grip free
play, turn the adjusting nut in di-
rection (a). To decrease the throt-
tle grip free play, turn the adjusting
nut in direction (b).
4. Tighten the locknut and then slide the rubber cover to its original po-
sition.
EAU21403
Valve clearanceThe valves are an important engine
component, and since valve clearance
changes with use, they must be
checked and adjusted at the intervals
specified in the periodic maintenance
chart. Unadjusted valves can result in
improper air-fuel mixture, engine
noise, and eventually engine damage.
To prevent this from occurring, have
your Yamaha dealer check and adjust
the valve clearance at regular intervals.TIPThis service must be performed when
the engine is cold.
1. Throttle grip free playThrottle g rip free play:
3.0–5.0 mm (0.12–0.20 in)
1
1. Adjusting nut
2. Locknut
1
2
(a)
(b)
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Periodic maintenance an d a djustment
6-21
6
EAUM1355
A djustin g the brake pe dal free
playMeasure the brake pedal free play as
shown.
Periodically check the brake pedal free
play and, if necessary, have a Yamaha
dealer adjust it.
WARNING
EWAM1031
An incorrect brake pe dal free play
in dicates a hazar dous con dition in
the brake system. Do not operate the motorcycle until the
brake sys-
tem has b een checked or repaired
b y a Yamaha dealer.
EAU36505
Brake li ght switchesThe brake light should come on just
before braking takes effect. The brake
light is activated by switches connect-
ed to the brake lever and brake pedal.
Since the brake light switches are
components of the anti-lock brake sys-
tem, they should only be serviced by a
Yamaha dealer.
1. Brake pedal free playBrake pe dal free play:
7.0–13.0 mm (0.28–0.51 in)
1
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Periodic maintenance an d a djustment
6-25
6
2. To tighten the drive chain, turn the drive chain slack adjusting bolt on
each side of the swingarm in di-
rection (a). To loosen the drive
chain, turn the adjusting bolt on
each side of the swingarm in di-
rection (b), and then push the rear
wheel forward.
TIPUsing the alignment marks on each
side of the swingarm, make sure that
both drive chain pullers are in the same
position for proper wheel alignment.
3. Tighten the axle nut, then the lock-nuts to their specified torques.
4. Make sure that the drive chain pullers are in the same position,
the drive chain slack is correct,
and the drive chain moves
smoothly.
EAU23026
Cleanin g an d lu bricatin g the
d rive chainThe drive chain must be cleaned and
lubricated at the intervals specified in
the periodic maintenance and lubrica-
tion chart, otherwise it will quickly wear
out, especially when riding in dusty or
wet areas. Service the drive chain as
follows.NOTICE
ECA10584
The drive chain must b e lubricate d
after washin g the motorcycle, ri din g
in the rain or ri din g in wet areas.1. Clean the drive chain with kero-
sene and a small soft brush.
NOTICE: To prevent d amaging
the O-rin gs, do not clean the
d rive chain with steam cleaners,
hi gh-pressure washers or inap-
propriate solvents.
[ECA11122]
2. Wipe the drive chain dry.
3. Thoroughly lubricate the drive chain with a special O-ring chain
lubricant. NOTICE: Do not use
en gine oil or any other lu bri-
cants for the drive chain, as they
1. Drive chain slack adjusting bolt
2. Axle nut
3. Alignment marks
4. LocknutZAUM1605
321
4
(b)
(a)
Ti
ghtenin g torques:
Axle nut: 85 N·m (8.5 kgf·m, 63 lb·ft)
Locknut:
15 N·m (1.5 kgf·m, 11 lb·ft)
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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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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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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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