check engine YAMAHA MT-125 2018 Owners Manual

Table of contents
Safety information............................1-1
Description........................................2-1
Left view ..........................................2-1
Right view........................................2-2
Controls and instruments ................2-3
Instrument and control functions....3-1
Main switch/steering lock ...............3-1
Indicator lights and warning
lights ............................................3-2
Multi-function meter unit .................3-4
Handlebar switches.......................3-12
Clutch lever ...................................3-13
Shift pedal .....................................3-14
Brake lever ....................................3-14
Brake pedal ...................................3-15
ABS ...............................................3-15
Fuel tank cap.................................3-16
Fuel................................................3-17
Catalytic converter ........................3-18
Rider seat ......................................3-19
Sidestand ......................................3-20
Ignition circuit cut-off system........3-20
For your safety – pre-operation
checks...............................................4-1
Operation and important riding
points.................................................5-1
Starting the engine ..........................5-2
Shifting ............................................5-3
Tips for reducing fuel
consumption ................................5-4
Engine break-in ...............................5-4
Parking ............................................5-5
Periodic maintenance and
adjustment........................................6-1
Owner’s tool kit ...............................6-2
Periodic maintenance chart for the
emission control system ..............6-3
General maintenance and
lubrication chart ...........................6-4
Removing and installing cowlings ...6-7
Checking the spark plug .................6-8Engine oil and oil filter element ....... 6-9
Coolant ......................................... 6-12
Replacing the air filter element
and cleaning the check hose..... 6-14
Checking the engine idling
speed......................................... 6-14
Adjusting the throttle grip free
play ............................................ 6-15
Valve clearance ............................. 6-16
Tires .............................................. 6-16
Cast wheels .................................. 6-19
Adjusting the clutch lever free
play ............................................ 6-19
Checking the front brake lever
free play ..................................... 6-20
Adjusting the brake pedal free
play ............................................ 6-21
Brake light switches ...................... 6-21
Checking the front and rear brake
pads........................................... 6-22
Checking the brake fluid level....... 6-23
Changing the brake fluid............... 6-24
Drive chain slack ........................... 6-24
Cleaning and lubricating the drive
chain .......................................... 6-26
Checking and lubricating the
cables ........................................ 6-26
Checking and lubricating the
throttle grip and cable ............... 6-27
Checking and lubricating the
brake and clutch levers ............. 6-27
Checking and lubricating the
brake pedal................................ 6-28
Checking and lubricating the
sidestand ................................... 6-28
Lubricating the swingarm
pivots ......................................... 6-29
Checking the front fork ................. 6-29
Checking the steering ................... 6-30
Checking the wheel bearings ....... 6-30
Battery .......................................... 6-31
Replacing the fuses ...................... 6-32
Replacing the headlight bulb ........ 6-33
Auxiliary lights ............................... 6-35
Tail/brake light .............................. 6-35
UBR3E1E0.book Page 1 Wednesday, August 10, 2016 9:45 AM

Safety information
1-3
1 Avoid Carbon Monoxide Poisoning
All engine exhaust contains carbon
monoxide, a deadly gas. Breathing
carbon monoxide can cause head-
aches, dizziness, drowsiness, nausea,
confusion, and eventually death.
Carbon Monoxide is a colorless, odor-
less, tasteless gas which may be pres-
ent even if you do not see or smell any
engine exhaust. Deadly levels of car-
bon monoxide can collect rapidly and
you can quickly be overcome and un-
able to save yourself. Also, deadly lev-
els of carbon monoxide can linger for
hours or days in enclosed or poorly
ventilated areas. If you experience any
symptoms of carbon monoxide poi-
soning, leave the area immediately, get
fresh air, and SEEK MEDICAL TREAT-
MENT.
Do not run engine indoors. Even if
you try to ventilate engine exhaust
with fans or open windows and
doors, carbon monoxide can rap-
idly reach dangerous levels.
Do not run engine in poorly venti-
lated or partially enclosed areas
such as barns, garages, or car-
ports.
Do not run engine outdoors where
engine exhaust can be drawn into
a building through openings such
as windows and doors.
Loading
Adding accessories or cargo to your
motorcycle can adversely affect stabil-
ity and handling if the weight distribu-
tion of the motorcycle is changed. To
avoid the possibility of an accident, use
extreme caution when adding cargo or
accessories to your motorcycle. Useextra care when riding a motorcycle
that has added cargo or accessories.
Here, along with the information about
accessories below, are some general
guidelines to follow if loading cargo to
your motorcycle:
The total weight of the operator, pas-
senger, accessories and cargo must
not exceed the maximum load limit.
Operation of an overloaded vehicle
could cause an accident.
When loading within this weight limit,
keep the following in mind:
Cargo and accessory weight
should be kept as low and close to
the motorcycle as possible. Se-
curely pack your heaviest items as
close to the center of the vehicle
as possible and make sure to dis-
tribute the weight as evenly as
possible on both sides of the mo-
torcycle to minimize imbalance or
instability.
Shifting weights can create a sud-
den imbalance. Make sure that
accessories and cargo are se-
curely attached to the motorcycle
before riding. Check accessory
mounts and cargo restraints fre-
quently.
• Properly adjust the suspension
for your load (suspension-ad-
justable models only), and
check the condition and pres-
sure of your tires.
• Never attach any large or heavy
items to the handlebar, front
fork, or front fender. These
items, including such cargo as
Maximum load:
180 kg (397 lb)
UBR3E1E0.book Page 3 Wednesday, August 10, 2016 9:45 AM

Safety information
1-5
1 operator and may limit control
ability, therefore, such accesso-
ries are not recommended.
Use caution when adding electri-
cal accessories. If electrical ac-
cessories exceed the capacity of
the motorcycle’s electrical sys-
tem, an electric failure could re-
sult, which could cause a
dangerous loss of lights or engine
power.
Aftermarket Tires and Rims
The tires and rims that came with your
motorcycle were designed to match
the performance capabilities and to
provide the best combination of han-
dling, braking, and comfort. Other
tires, rims, sizes, and combinations
may not be appropriate. Refer to page
6-16 for tire specifications and more in-
formation on replacing your tires.
Transporting the Motorcycle
Be sure to observe following instruc-
tions before transporting the motorcy-
cle in another vehicle.
Remove all loose items from the
motorcycle.
Check that the fuel cock (if
equipped) is in the “OFF” position
and that there are no fuel leaks.
Point the front wheel straight
ahead on the trailer or in the truck
bed, and choke it in a rail to pre-
vent movement.
Shift the transmission in gear (for
models with a manual transmis-
sion).
Secure the motorcycle with tie-
downs or suitable straps that are
attached to solid parts of the mo-torcycle, such as the frame or up-
per front fork triple clamp (and not,
for example, to rubber-mounted
handlebars or turn signals, or
parts that could break). Choose
the location for the straps carefully
so the straps will not rub against
painted surfaces during transport.
The suspension should be com-
pressed somewhat by the tie-
downs, if possible, so that the mo-
torcycle will not bounce exces-
sively during transport.
UBR3E1E0.book Page 5 Wednesday, August 10, 2016 9:45 AM

Instrument and control functions
3-3
3 The electrical circuit of the warning
light can be checked according to the
following procedure.
1. Turn the key to “ON”.
2. If the warning light does not come
on, have a Yamaha dealer check
the electrical circuit.
EAU11486Engine trouble warning light “ ”
This warning light comes on if a prob-
lem is detected in the electrical circuit
monitoring the engine. If this occurs,
have a Yamaha dealer check the vehi-
cle.
The electrical circuit of the warning
light can be checked by turning the key
to “ON”. The warning light should
come on for a few seconds, and then
go off.
If the warning light does not come on
initially when the key is turned to “ON”,
or if the warning light remains on, have
a Yamaha dealer check the electrical
circuit.
EAU69890ABS warning light “ ”
In normal operation, the ABS warning
light comes on when the key is turned
to “ON”, and goes off after traveling at
a speed of 10 km/h (6 mi/h) or higher.
If the ABS warning light:
does not come on when the key is
turned to “ON”
comes on or flashes while riding
does not go off after traveling at a
speed of 10 km/h (6 mi/h) or high-
erThe ABS may not work correctly. If any
of the above occurs, have a Yamaha
dealer check the system as soon as
possible. (See page 3-15 for an expla-
nation of the ABS.)
WARNING
EWA16041
If the ABS warning light does not go
off after traveling at a speed of 10
km/h (6 mi/h) or higher, or if the
warning light comes on or flashes
while riding, the brake system re-
verts to conventional braking. If ei-
ther of the above occurs, or if the
warning light does not come on at
all, use extra caution to avoid possi-
ble wheel lock during emergency
braking. Have a Yamaha dealer
check the brake system and electri-
cal circuits as soon as possible.
EAUM3440Tachometer high-rpm warning light
This light flashes at 9500 r/min to warn
you that the engine speed is about to
enter the high-rpm zone. Once the en-
gine speed reaches 10000 r/min, this
light will come on to warn you that it is
necessary to shift up to avoid engine
damage.
To activate or deactivate the tachome-
ter high-rpm warning light, hold the
“INFO” button pushed, turn the key to
“ON”, and when the tachometer high-
rpm warning light starts flashing, press
the “SELECT” button.
TIP
When activating or deactivating the
warning light the function, after press-

ABS
UBR3E1E0.book Page 3 Wednesday, August 10, 2016 9:45 AM

Instrument and control functions
3-6
32. Push the “SELECT” button for two
seconds, and the hour digits will
start flashing.
3. Use the “RESET” button to set the
hours.
4. Push the “SELECT” button, and
the minute digits will start flashing.
5. Use the “RESET” button to set the
minutes.
6. Push the “SELECT” button to con-
firm settings and start the clock.
TIP
When setting the hours and minutes, a

creases the increment value one by
one. You may also push and hold the
button to increase the value continu-
ously.
Fuel meter
The fuel meter indicates the amount of
fuel in the fuel tank. The display seg-
ments of the fuel meter disappear from
“F” (full) towards “E” (empty) as the fuel
level decreases. When the fuel level
becomes low, the last segment will
flash and the fuel level warninglight “ ” will come on (“LOW FUEL”
message will also appear). Refuel as
soon as possible.
TIP
If a problem is detected in the fuel me-
ter electrical circuit, all display seg-
ments of the fuel meter will flash eight
times, then go off for 3 seconds, re-
peatedly. If this occurs, have your
Yamaha dealer check the vehicle.
Coolant temperature meter
The coolant temperature meter indi-
cates the temperature of the coolant,
and therefore the engine. When the
coolant temperature is at its upper lim-
it, the second segment from the top
will start to flash. Should this occur, re-
duce the load on the engine by riding at
a moderate pace, at low rpm, until the
coolant temperature goes down. If the
top two segments and “ ” start flash-
ing (“HIGH TEMP” message will also
appear), stop the vehicle and let the
engine cool.
1. Fuel meter
2. Fuel level warning light “ ”
3. Fuel reserve tripmeter
4. Information display
Lo
Hi
1/2
x1000r/min
ZAUM1303
km/h
FTRIP
21
34
1. Coolant temperature warning indicator Ž
2. Information display
3. Coolant temperature meter
Lo
Hi
ZAUM1304
31
2
UBR3E1E0.book Page 6 Wednesday, August 10, 2016 9:45 AM

Instrument and control functions
3-18
3TIP
This mark identifies the recom-
mended fuel for this vehicle as
specified by European regulation
(EN228).
 Check that gasoline nozzle has
the same identifier when fueling.
Your Yamaha engine has been de-
signed to use premium unleaded gas-
oline with a research octane number of
95 or higher. If knocking (or pinging)
occurs, use a gasoline of a different
brand. Use of unleaded fuel will extend
spark plug life and reduce mainte-
nance costs.
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.
EAU13434
Catalytic converter
This model is equipped with a catalytic
converter in the exhaust system.
WARNING
EWA10863
The exhaust system is hot after op-
eration. To prevent a fire hazard or
burns:
 Do not park the vehicle near
possible fire hazards such as
grass or other materials that
easily burn.
 Park the vehicle in a place
where pedestrians or children
are not likely to touch the hot
exhaust system.
 Make sure that the exhaust sys-
tem has cooled down before
doing any maintenance work.
 Do not allow the engine to idle
more than a few minutes. Long
idling can cause a build-up of
heat.
NOTICE
ECA10702
Use only unleaded gasoline. The use
of leaded gasoline will cause unre-
pairable damage to the catalytic
converter.
E5E10
UBR3E2E0.book Page 18 Friday, May 11, 2018 11:08 AM

Instrument and control functions
3-20
3
EAU15306
Sidestand
The sidestand is located on the left
side of the frame. Raise the sidestand
or lower it with your foot while holding
the vehicle upright.
TIP
The 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 ridden with
the sidestand down, or if the side-
stand cannot be properly moved up
(or does not stay up), otherwise the
sidestand could contact the ground
and distract the operator, resulting
in a possible loss of control.
Yamaha’s ignition circuit cut-off
system has been designed to assist
the operator in fulfilling the respon-
sibility of raising the sidestand be-
fore starting off. Therefore, check
this system regularly and have a
Yamaha dealer repair it if it does not
function properly.
EAU66730
Ignition circuit cut-off system
The ignition circuit cut-off system
(comprising the sidestand switch,
clutch switch and neutral switch) has
the following functions.
It prevents starting when the
transmission is in gear and the
sidestand is up, but the clutch le-
ver is not pulled.
It prevents starting when the
transmission is in gear and the
clutch lever is pulled, but the side-
stand is still down.
It cuts the running engine when
the transmission is in gear and the
sidestand is moved down.
Periodically check the operation of the
ignition circuit cut-off system accord-
ing to the following procedure.
UBR3E1E0.book Page 20 Wednesday, August 10, 2016 9:45 AM

Instrument and control functions
3-21
3
With the engine turned off:
1. Move the sidestand down.
2.
Make sure that the engine stop switch
is set to “ ”.
3. Turn the key on.
4. Shift the transmission into the neutral
position.
5. Push the start switch.
Does the engine start?
With the engine still running:
6. Move the sidestand up.
7. Keep the clutch lever pulled.
8. Shift the transmission into gear.
9. Move the sidestand down.
Does the engine stall?
After the engine has stalled:
10. Move the sidestand up.
11. Keep the clutch lever pulled.
12. Push the start switch.
Does the engine start?
The system is OK. The motorcycle can
be ridden.
The neutral switch may not be working
correctly.
The motorcycle should not be ridden
until checked by a Yamaha dealer.
The sidestand switch may not be
working correctly.
The motorcycle should not be ridden
until checked by a Yamaha dealer.
The clutch switch may not be working
correctly.
The motorcycle should not be ridden
until checked by a Yamaha dealer.
WARNING
If a malfunction is noted, have a
Yamaha dealer check the system
before riding.
YES NO
YES NO
YES NO
UBR3E1E0.book Page 21 Wednesday, August 10, 2016 9:45 AM

For your safety – pre-operation checks
4-1
4
EAU63440
Inspect your vehicle each time you use it to make sure the vehicle is in safe oper-
ating 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 accident or equipment damage. Do not operate the vehicle if you find
any problem. If a problem cannot be corrected by the procedures provided
in this manual, have the vehicle inspected by 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.3-17
Engine oil• Check oil level in engine.
• If necessary, add recommended oil to specified level.
• Check vehicle for oil leakage.6-9
Coolant• Check coolant level in reservoir.
• If necessary, add recommended coolant to specified
level.
• Check cooling system for leakage.6-12
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,
6-23
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,
6-23
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 cable and grip housing.6-15,
6-27
UBR3E1E0.book Page 1 Wednesday, August 10, 2016 9:45 AM

Operation and important riding points
5-2
5
EAUM3531
Starting the engine
In order for the ignition circuit cut-off
system to enable starting, one of the
following conditions must be met:
The transmission is in the neutral
position.
The transmission is in gear with
the clutch lever pulled and the
sidestand up.
See page 3-20 for more informa-
tion.
1. Turn the key to “ON” and make
sure that the engine stop switch is
set to “ ”.
The following warning lights and
indicator lights should come on for
a few seconds, then go off.
Neutral indicator light
Turn signal indicator light
High beam indicator light
Engine trouble warning light
Fuel level warning light
Tachometer high-rpm warn-
ing light
NOTICE
ECA11834
If a warning or indicator light does
not come on initially when the key is
turned to “ON”, or if a warning or in-
dicator light remains on, see page
3-2 for the corresponding warning
and indicator light circuit check.
The ABS warning light should
come on when the key is turned to
“ON”, and then go off after travel-
ing at a speed of 10 km/h (6 mi/h)
or higher.
NOTICE
ECA17682
If the ABS warning light does not
come on and then go off as ex-
plained above, see page 3-2 for the
warning light circuit check.
2. Shift the transmission into the
neutral position. The neutral indi-
cator light should come on. If not,
ask a Yamaha dealer to check the
electrical circuit.
3. Start the engine by pushing the
start switch.
If the engine fails to start, release
the start switch, wait a few sec-
onds, and then try again. Each
starting attempt should be as
short as possible to preserve the
battery. Do not crank the engine
more than 10 seconds on any one
attempt.
NOTICE
ECA11043
For maximum engine life, never ac-
celerate hard when the engine is
cold!
UBR3E1E0.book Page 2 Wednesday, August 10, 2016 9:45 AM