fuel YAMAHA MT-125 2021 User Guide

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
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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
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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
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Operation and important rid ing points
5-4
5 The neutral indicator light should
come on and then the clutch lever
can be released.
WARNING
EWA17380

Improper brakin g can cause
loss of control or traction. Al-
ways use b oth brakes an d apply
them smoothly.
 Make sure that the motorcycle
and the en gine have sufficiently
slowe d b efore shiftin g to a low-
er gear. En gag in g a lower gear
when the vehicle or en gine
speed is too hi gh coul d make
the rear wheel lose traction or
the en gine to over-rev. This
coul d cause loss of control, an
acci dent an d injury. It coul d also
cause en gine or drive train dam-
a g e.
EAU16811
Tips for re ducin g fuel con-
sumptionFuel consumption depends largely on
your riding style. Consider the follow-
ing tips to reduce fuel consumption:
 Shift up swiftly, and avoid high en-
gine speeds during acceleration.
 Do not rev the engine while shift-
ing down, and avoid high engine
speeds with no load on the en-
gine.
 Turn the engine off instead of let-
ting it idle for an extended length
of time (e.g., in traffic jams, at traf-
fic lights or at railroad crossings).
EAU17214
Parkin gWhen parking, stop the engine, and
then remove the key from the main
switch.
WARNING
EWA10312
Since the en gine an d exhaust
system can become very hot,
park in a place where pe destri-
ans or chil dren are not likely to
touch them an d b e burne d.
 Do not park on a slope or on soft
groun d, otherwise the vehicle
may overturn, increasin g the
risk of a fuel leak an d fire.
 Do not park near grass or other
flammab le materials which
mi ght catch fire.
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Periodic maintenance an d a djustment
6-3
6
EAU71021
TIP The annual checks must be performe d every year, except if a distance- based maintenance is performe d in-
stea d.
 From 30000 km (17500 mi), repeat the maintenance intervals starting from 6000 km (3500 mi).
 Items marked with an asterisk should be performed by a Yamaha dealer as they require special tools, data and tech-
nical skills.
EAU71041
Perio dic maintenance chart for the emission control systemNO. 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)
1 *Fuel line • Check fuel hoses for cracks or
damage.
• Replace if necessary. √√√√√
2 *Spark plu g • Check condition.
• Adjust gap and clean.
√√
•Replace. √√
3 *Valve clearance • Check and adjust. √√√√
4 *Fuel injection • Check and adjust engine idle
speed. √√√√√√
5 *Exhaust system • Check for leakage.
• Tighten if necessary.
• Replace gasket if necessary. √√√√√
6 *Evaporative emis-
sion control system • Check control system for dam-
age.
• Replace if necessary. √√
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Periodic maintenance an d a djustment
6-9
6
Before installing a spark plug, the
spark plug gap should be measured
with a wire thickness gauge and, if
necessary, adjusted to specification.
Clean the surface of the spark plug
gasket and its mating surface, and
then wipe off any grime from the spark
plug threads.
TIPIf a torque wrench is not available
when installing a spark plug, a good
estimate of the correct torque is 1/4–
1/2 turn past finger tight. However, the
spark plug should be tightened to the
specified torque as soon as possible.
EAU36112
CanisterThis model is equipped with a canister
to prevent the discharging of fuel vapor
into the atmosphere. Before operating
this vehicle, make sure to check the
following:
 Check each hose connection.
 Check each hose and canister for
cracks or damage. Replace if
damaged.
 Make sure that the canister
breather is not blocked, and if
necessary, clean it.
1. Spark plug gapSpark plu g g ap:
0.8–0.9 mm (0.031–0.035 in)
Ti ghtenin g torque:
Spark plug: 12.5 N·m (1.25 kgf·m, 9.22 lb·ft)
1
ZAUM0037
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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
6-34
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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Periodic maintenance an d a djustment
6-35
6
EAU86350
Trou bleshootin g chart
Check the fuel level in
the fuel tank.1. Fuel
There is enough fuel.
There is no fuel.
Check the battery.
Supply fuel.
The engine does not start.
Check the battery.
Try starting the engine.4. Compression
There is compression.
There is no compression.
The engine does not start.
Have a Yamaha dealer check the vehicle.Have a Yamaha dealer check the vehicle.
Remove the spark plug
and check the electrodes.3. Ignition
Wipe off with a dry cloth and correct the
spark plug gap, or replace the spark plug(s). Have a Yamaha dealer check the vehicle.
The engine does not start.
Check the compression.
Operate the electric starter.2. Battery
The engine turns over
quickly.
The engine turns over
slowly.
The battery is good.
DryWet
Try starting the engine.
Check the battery lead connections,
and charge the battery if necessary.
The engine does not start.
Check the ignition.
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Motorcycle care and stora ge
7-3
7
will
become slippery, which
coul d cause loss of control.
Thorou ghly clean the surfaces
of these parts before operatin g
the vehicle.
[EWA20650]
5. Treat rubber, vinyl, and unpainted plastic parts with a suitable care
product.
6. Touch up minor paint damage caused by stones, etc.
7. Wax all painted surfaces using a non-abrasive wax or use a detail
spray for motorcycles.
8. When finished cleaning, start the engine and let it idle for several
minutes to help dry any remaining
moisture.
9. If the headlight lens has fogged up, start the engine and turn on
the headlight to help remove the
moisture.
10. Let the vehicle dry completely be- fore storing or covering it.NOTICE
ECA26320
Do not apply wax to ru bber or
unpainte d plastic parts. 
Do not use a brasive polishin g
compoun ds as they will wear
away the paint.
 Apply sprays an d wax sparin gly.
Wipe off excess afterwar ds.
WARNING
EWA20660
Contaminants left on the brakes or
tires can cause loss of control.  Make sure there is no lu bricant
or wax on the brakes or tires.
 If necessary, wash the tires with
warm water an d a mil d d eter-
g ent.
 If necessary, clean the b rake
d iscs an d pa ds with b rake
cleaner or acetone.
 Before ri din g at hi gher spee ds,
test the vehicle’s brakin g per-
formance an d cornerin g b ehav-
ior.
EAU83472
Stora geAlways store the vehicle in a cool, dry
place. If necessary, protect it against
dust with a porous cover. Be sure the
engine and the exhaust system are
cool before covering the vehicle. If the
vehicle often sits for weeks at a time
between uses, the use of a quality fuel
stabilizer is recommended after each
fill-up.NOTICE
ECA21170
 Storin g the vehicle in a poorly
ventilate d room or coverin g it
with a tarp, while it is still wet,
will allow water an d humi dity to
seep in an d cause rust.
 To prevent corrosion, avoi d
d amp cellars, stab les (because
of the presence of ammonia)
an d areas where stron g chemi-
cals are stored .Long term stora ge
Before storing the vehicle long term (60
days or more):
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