2021 YAMAHA YZF-R125 check engine

Periodic maintenance an d a djustment
6-14
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.
EAUE3460
To check the coolant level
1. Place the vehicle on a level sur- face.
2. Remove cowling C of left side. (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.
6. Add coolant to the maximum level mark, and then install the coolant
reservoir cap. WARNING! Re-
move only the coolant reservoir
cap. Never attempt to remove
the ra diator cap when the en-
g ine is hot.
[EWA15162]
NOTICE: If
coolant is not availa ble, use dis-
tille d water or soft tap water in-
stead . Do not use har d water or
salt water since it is harmful to
the en gine. If water has been
use d instead of coolant, replace
it with coolant as soon as possi-
b le, otherwise the coolin g sys-
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
2
3
FULL
LOW
ZAUE3384
1. Coolant reservoir cap
1ZAUE3385
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Periodic maintenance an d a djustment
6-16
6
EAU34302
A djustin g the eng ine idlin g
spee dThe engine idling speed must be
checked and, if necessary, adjusted as
follows at the intervals specified in the
periodic maintenance and lubrication
chart.
The engine should be warm before
making this adjustment.
Check the engine idling speed and, if
necessary, adjust it to specification by
turning the idle adjusting screw. To in-
crease the engine idling speed, turn
the screw in direction (a). To decrease
the engine idling speed, turn the screw
in direction (b).
TIPIf the specified idling speed cannot be
obtained as described above, have a
Yamaha dealer make the adjustment.
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.
1. Idle adjusting screwZAUE3388
(a)
(b)
1
En gine i dlin g spee d:
1250–1550 r/min
1. Throttle grip free playThrottle grip free play:
3.0–5.0 mm (0.12–0.20 in)ZAUM1595
1
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Periodic maintenance an d a djustment
6-17
6
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.
EAU77621
TiresTires are the only contact between the
vehicle and the road. Safety in all con-
ditions of riding depends on a relatively
small area of road contact. Therefore, it
is essential to maintain the tires in good
condition at all times and replace them
at the appropriate time with the speci-
fied tires.
Tire air pressure
The tire air pressure should be
checked and, if necessary, adjusted
before each ride.
WARNING
EWA10504
Operation of this vehicle with im-
proper tire pressure may cause se-
vere injury or d eath from loss of
control.  The tire air pressure must be
checked and a djuste d on col d
tires (i.e., when the temperature
of the tires equals the am bient
temperature).
 The tire air pressure must be
a d juste d in accor dance with the
ri din g spee d an d with the total
1. Adjusting nut
2. LocknutZAUM1596
1 2
(a)
(b)
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Periodic maintenance an d a djustment
6-36
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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Periodic maintenance an d a djustment
6-37
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 down 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.
UB5GE2E0.book Page 37 Thursday, July 30, 2020 3:08 PM

Motorcycle care and stora ge
7-4
7
1. Make all necessary repairs and
perform any outstanding mainte-
nance.
2. Follow all instructions in the Care section of this chapter.
3. Fill up the fuel tank, adding fuel stabilizer according to product in-
structions. Run the engine for 5
minutes to distribute treated fuel
through the fuel system.
4. For vehicles equipped with a fuel cock: Turn the fuel cock lever to
the off position.
5. For vehicles with a carburetor: To prevent fuel deposits from build-
ing up, drain the fuel in the carbu-
retor float chamber into a clean
container. Retighten the drain bolt
and pour the fuel back into the fuel
tank.
6. Use a quality engine fogging oil according to product instructions
to protect internal engine compo-
nents from corrosion. If engine
fogging oil is not available, per-
form the following steps for each
cylinder:a. Remove the spark plug cap and spark plug. b. Pour a teaspoonful of engine
oil into the spark plug bore.
c. Install the spark plug cap onto the spark plug, and then place
the spark plug on the cylinder
head so that the electrodes are
grounded. (This will limit spark-
ing during the next step.)
d. Turn the engine over several times with the starter. (This will
coat the cylinder wall with oil.)
WARNING! To prevent dam-
a g e or injury from sparkin g,
make sure to groun d the
spark plu g electro des while
turnin g the en gine over.
[EWA10952]
e. Remove the spark plug cap
from the spark plug, and then
install the spark plug and the
spark plug cap.
7. Lubricate all control cables, piv- ots, levers and pedals, as well as
the sidestand and centerstand (if
equipped).
8. Check and correct the tire air pressure, and then lift the vehicle
so that all wheels are off the
ground. Otherwise, turn the wheels a little once a month in or-
der to prevent the tires from be-
coming degraded in one spot.
9. Cover the muffler outlet with a plastic bag to prevent moisture
from entering it.
10. Remove the battery and fully charge it, or attach a maintenance
charger to keep the battery opti-
mally charged. NOTICE: Confirm
that the battery an d its char ger
are compati ble. Do not char ge a
VRLA battery with a convention-
al char ger.
[ECA26330]
TIP If the battery will be removed,
charge it once a month and store
it in a temperate location between
0-30 °C (32-90 °F).
 See page 6-31 for more informa-
tion on charging and storing the
battery.
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Consumer information
9-2
9
The model label is affixed to the frame
under the rider seat. (See page 3-19.)
Record 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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10-1
10
Index
AABS....................................................... 3-15
ABS warning light ................................... 3-3
Air filter element and check hose,
replacing and cleaning ....................... 6-15BBattery .................................................. 6-31
Brake and clutch levers, checking and lubricating........................................... 6-28
Brake and shift pedals, checking and lubricating........................................... 6-27
Brake fluid, changing............................ 6-24
Brake fluid level, checking.................... 6-23
Brake lever............................................ 3-14
Brake light switches ............................. 6-22
Brake pedal .......................................... 3-14
Brake pedal free play, adjusting ........... 6-21CCables, checking and lubricating ......... 6-27
Canister ................................................ 6-10
Care ........................................................ 7-1
Catalytic converter ............................... 3-19
Clutch lever........................................... 3-13
Clutch lever free play, adjusting ........... 6-20
Coolant ................................................. 6-14
Coolant temperature warning light ......... 3-2
Cowlings, removing and installing.......... 6-8DData recording, vehicle........................... 9-2
Diagnostic connector ............................. 9-2
Dimmer/Pass switch............................. 3-13
Drive chain, cleaning and lubricating ... 6-26
Drive chain slack .................................. 6-25
EEngine break-in ...................................... 5-1
Engine idling speed.............................. 6-16
Engine oil and oil filter element ............ 6-11
Engine overheating .............................. 6-37
Engine serial number ............................. 9-1
Engine stop switch............................... 3-13FFront and rear brake pads, checking ... 6-22
Front brake lever free play, checking ... 6-21
Front fork, checking ............................. 6-29
Fuel ...................................................... 3-16
Fuel consumption, tips for reducing ...... 5-4
Fuel tank breather hose and overflow hose ................................................... 3-18
Fuel tank cap........................................ 3-16
Fuses, replacing ................................... 6-32HHandlebar switches ............................. 3-12
High beam indicator light ....................... 3-2
Horn switch .......................................... 3-13IIdentification numbers ........................... 9-1
Ignition circuit cut-off system .............. 3-21
Indicator lights and warning lights ......... 3-2LLicense plate light bulb, replacing ....... 6-34MMain switch/steering lock ...................... 3-1
Maintenance and lubrication, periodic... 6-4
Maintenance, emission control system ................................................. 6-3
Malfunction indicator light (MIL)............. 3-3
Matte color, caution ............................... 7-1 Model label ............................................. 9-1
Multi-function meter unit ........................ 3-4
NNeutral indicator light ............................. 3-2PParking.................................................... 5-4
Part locations.......................................... 2-1RRear suspension, lubricating ................ 6-29SSafety information................................... 1-1
Seats ..................................................... 3-19
Shifting.................................................... 5-3
Shift light ................................................. 3-3
Shift pedal............................................. 3-14
Sidestand.............................................. 3-20
Sidestand, checking and lubricating .... 6-29
Spark plug, checking .............................. 6-9
Specifications ......................................... 8-1
Starting the engine ................................. 5-2
Start switch ........................................... 3-13
Steering, checking ................................ 6-30
Storage ................................................... 7-3
Supporting the motorcycle ................... 6-34TTail/brake light ...................................... 6-33
Throttle grip and cable, checking and
lubricating ........................................... 6-27
Throttle grip free play, adjusting ........... 6-16
Tires ...................................................... 6-17
Tool kit .................................................... 6-2
Troubleshooting .................................... 6-35
Troubleshooting chart........................... 6-36
Turn signal indicator light ....................... 3-2
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