Page 30 of 96
INSTRUMENT AND CONTROL FUNCTIONS
3-15
3
EAUM2082
Fuel tank capTo remove the fuel tank cap
1. Open the fuel tank cap lock cover.
2. Insert the key into the lock and
turn it 1/4 turn counterclockwise.
The lock will be released and the
fuel tank cap can be removed.
To install the fuel tank cap
1. Push the fuel tank cap into posi-
tion with the key inserted in the
lock.
2. Turn the key clockwise to the orig-
inal position, and then remove it.
3. Close the lock cover.
TIPThe fuel tank cap cannot be installed
unless the key is in the lock. In addi-
tion, the key cannot be removed if the
cap is not properly installed and
locked.
WARNING
EWA11142
Make sure that the fuel tank cap is
properly installed before riding.
Leaking fuel is a fire hazard.
1. Front wheel sensor rotor
2. Front wheel sensor
1. Rear wheel sensor rotor
2. Rear wheel sensorZAUM122712ZAUM122812
1. Fuel tank cap lock cover
2. Unlock.
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        Page 33 of 96

INSTRUMENT AND CONTROL FUNCTIONS
3-18
3
EAUM2461
Rider seatTo remove the rider seat
1. Insert the key into the seat lock,
and then turn it clockwise.
2. Pull the rider seat off.
To install the rider seat
1. Insert the projection on the front of
the rider seat into the seat holder
as shown.2. Push the rear of the rider seat
down to lock it in place.
3. Turn the key counterclockwise,
and then remove it.
TIPMake sure that the rider seat is proper-
ly secured before riding.
EAU15306
SidestandThe sidestand is located on the left
side of the frame. Raise the sidestand
or lower it with your foot while holding
the vehicle upright.TIPThe 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
1. Seat lock
2. Open.
1. Projection
2. Seat holder
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        Page 57 of 96

PERIODIC MAINTENANCE AND ADJUSTMENT
6-15
6
EAU44735
Checking the engine idling 
speedCheck the engine idling speed and, if
necessary, have it corrected by a
Yamaha dealer.
EAU48433
Adjusting the throttle grip free 
playThe throttle grip free play should mea-
sure 3.0–5.0 mm (0.12–0.20 in) at the
inner edge of the throttle grip. Periodi-
cally check the throttle grip free play
and, if necessary, adjust it as follows.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.
Engine idling speed:
1350–1550 r/min
1. Throttle grip free play
1
1. Rubber cover
2. Adjusting nut
3. LocknutZAUM12081
23
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        Page 61 of 96

PERIODIC MAINTENANCE AND ADJUSTMENT
6-19
6
EAU21963
Cast wheelsTo maximize the performance, durabil-
ity, and safe operation of your vehicle,
note the following points regarding the
specified wheels.
The wheel rims should be
checked for cracks, bends, warp-
age or other damage before each
ride. If any damage is found, have
a Yamaha dealer replace the
wheel. Do not attempt even the
smallest repair to the wheel. A de-
formed or cracked wheel must be
replaced.
The wheel should be balanced
whenever either the tire or wheel
has been changed or replaced. An
unbalanced wheel can result in
poor performance, adverse han-
dling characteristics, and a short-
ened tire life.
EAU22045
Adjusting the clutch lever free 
playThe clutch lever free play should mea-
sure 10.0–15.0 mm (0.39–0.59 in) as
shown. Periodically check the clutch
lever free play and, if necessary, adjust
it as follows.
1. Slide the rubber cover back at the
clutch lever.
2. Loosen the locknut.
3. To increase the clutch lever free
play, turn the clutch lever free play
adjusting bolt in direction (a). To
decrease the clutch lever free
play, turn the adjusting bolt in di-
rection (b).
TIPIf the specified clutch lever free play
could be obtained as described above,
skip steps 4–7.4. Fully turn the adjusting bolt at the
clutch lever in direction (a) to loos-
en the clutch cable.
5. Loosen the locknut at the crank-
case.
6. To increase the clutch lever free
play, turn the clutch lever free play
adjusting nut in direction (a). To
decrease the clutch lever free
play, turn the adjusting nut in di-
rection (b).
1. Clutch lever free play adjusting bolt
2. Clutch lever free play
1. Locknut
2. Clutch lever free play adjusting nut (crank-
case)
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        Page 62 of 96

PERIODIC MAINTENANCE AND ADJUSTMENT
6-20
67. Tighten the locknut at the crank-
case.
8. Tighten the locknut at the clutch
lever and then slide the rubber
cover to its original position.
EAUT1222
Checking the front brake lever 
free playThe brake lever free play should mea-
sure 2.0–5.0 mm (0.08–0.20 in) as
shown. Periodically check the brake le-
ver free play and, if necessary, have a
Yamaha dealer check the brake sys-
tem.
WARNING
EWA10642
An incorrect brake lever free play in-
dicates a hazardous condition in the
brake system. Do not operate the
vehicle until the brake system has
been checked or repaired by a
Yamaha dealer.
EAUM1354
Adjusting the brake pedal free 
playThe brake pedal free play should mea-
sure 3.5–4.5 mm (0.14–0.18 in) as
shown. Periodically check the brake
pedal free play and, if necessary, have
a Yamaha dealer adjust it.
WARNING
EWAM1031
An incorrect brake pedal free play
indicates a hazardous condition in
the brake system. Do not operate
the motorcycle until the brake sys-
tem has been checked or repaired
by a Yamaha dealer.
1. Brake lever free playZAUM1179
INFOINFO
1. Brake pedal free play
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        Page 65 of 96

PERIODIC MAINTENANCE AND ADJUSTMENT
6-23
6 Use only the specified brake flu-
id; otherwise, the rubber seals
may deteriorate, causing leak-
age.
Refill with the same type of
brake fluid. Adding a brake fluid
other than DOT 4 may result in a
harmful chemical reaction.
Be careful that water or dust
does not enter the brake fluid
reservoir when refilling. Water
will significantly lower the boil-
ing point of the fluid and may re-
sult in vapor lock, and dirt may
clog the ABS hydraulic unit
valves.
NOTICE
ECA17641
Brake fluid may damage painted
surfaces or plastic parts. Always
clean up spilled fluid immediately.As the brake pads wear, it is normal for
the brake fluid level to gradually go
down. A low brake fluid level may indi-
cate worn brake pads and/or brake
system leakage; therefore, be sure to
check the brake pads for wear and the
brake system for leakage. If the brakefluid level goes down suddenly, have a
Yamaha dealer check the cause before
further riding.
EAU22733
Changing the brake fluidHave a Yamaha dealer change the
brake fluid at the intervals specified in
the periodic maintenance and lubrica-
tion chart. In addition, have the oil seals
of the master cylinders and calipers as
well as the brake hoses replaced at the
intervals listed below or whenever they
are damaged or leaking.
Oil seals: Replace every two
years.
Brake hoses: Replace every four
years.
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        Page 66 of 96

PERIODIC MAINTENANCE AND ADJUSTMENT
6-24
6
EAU22762
Drive chain slackThe drive chain slack should be
checked before each ride and adjusted
if necessary.
EAUM3550
To check the drive chain slack
1. Place the motorcycle on the side-
stand.TIPWhen checking and adjusting the drive
chain slack, there should be no weight
on the motorcycle.2. Shift the transmission into the
neutral position.
3. Measure the drive chain slack at
the arrow mark on the swingarm
as shown in the illustration.4. If the drive chain slack is incorrect,
adjust it as follows.
EAU34318
To adjust the drive chain slack
Consult a Yamaha dealer before ad-
justing the drive chain slack.
1. Loosen the axle nut and the lock-
nut on each side of the swingarm.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. NOTICE: Improp-
er drive chain slack will over-
load the engine as well as other
vital parts of the motorcycle and
can lead to chain slippage or
breakage. To prevent this from
Drive chain slack:
35.0–45.0 mm (1.38–1.77 in)
1. Drive chain slackZAUM1233
1. Axle nut
2. Drive chain slack adjusting bolt
3. Locknut
4. Alignment marksZAUM1183
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        Page 67 of 96
![YAMAHA MT-125 2015  Owners Manual PERIODIC MAINTENANCE AND ADJUSTMENT
6-25
6 occurring, keep the drive chain
slack within the specified limits.
[ECA10572]
TIPUsing the alignment marks on each
side of the swingarm, make sure that
both  YAMAHA MT-125 2015  Owners Manual PERIODIC MAINTENANCE AND ADJUSTMENT
6-25
6 occurring, keep the drive chain
slack within the specified limits.
[ECA10572]
TIPUsing the alignment marks on each
side of the swingarm, make sure that
both](/manual-img/51/50974/w960_50974-66.png)
PERIODIC MAINTENANCE AND ADJUSTMENT
6-25
6 occurring, keep the drive chain
slack within the specified limits.
[ECA10572]
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
Cleaning and lubricating the 
drive 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 be lubricated
after washing the motorcycle, riding
in the rain or riding in wet areas.1. Clean the drive chain with kero-
sene and a small soft brush.
NOTICE: To prevent damaging
the O-rings, do not clean the
drive chain with steam cleaners,
high-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
engine oil or any other lubri-
cants for the drive chain, as theymay contain substances that
could damage the O-rings.
[ECA11112]
Tightening torques:
Axle nut:
85 Nm (8.5 m·kgf, 61 ft·lbf)
Locknut:
16 Nm (1.6 m·kgf, 12 ft·lbf)
U5D7E4E0.book  Page 25  Thursday, July 10, 2014  3:01 PM