light YAMAHA MT-25 2016 Owner's Manual

Periodic maintenance and adjustment
6-8
6
EAU19643
Checking the spark plugsThe spark plugs are important engine
components, which should be
checked periodically, preferably by a
Yamaha dealer. Since heat and depos-
its will cause any spark plug to slowly
erode, they should be removed and
checked in accordance with the peri-
odic maintenance and lubrication
chart. In addition, the condition of the
spark plugs can reveal the condition of
the engine.
The porcelain insulator around the
center electrode of each spark plug
should be a medium-to-light tan (the
ideal color when the vehicle is ridden
normally), and all spark plugs installed
in the engine should have the same
color. If any spark plug shows a dis-
tinctly different color, the engine could
be operating improperly. Do not at-
tempt to diagnose such problems
yourself. Instead, have a Yamaha deal-
er check the vehicle.
If a spark plug shows signs of elec-
trode erosion and excessive carbon or
other deposits, it should be replaced.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.
Specified spark plug:
NGK/CR9E
1. Spark plug gap
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)
Tightening torque:
Spark plug:
13 Nm (1.3 m·kgf, 9.4 ft·lbf)
UB04E0E0.book Page 8 Wednesday, September 2, 2015 3:51 PM

Periodic maintenance and adjustment
6-9
6
EAUN1150
Engine oil and oil filter car-
tridgeThe engine oil level should be checked
before each ride. In addition, the oil
must be changed and the oil filter car-
tridge replaced at the intervals speci-
fied in the periodic maintenance and
lubrication chart.
To check the engine oil level
1. Place the vehicle on a level sur-
face and hold it in an upright posi-
tion. A slight tilt to the side can
result in a false reading.
2. Start the engine, warm it up for
several minutes, and then turn it
off.
3. Wait a few minutes until the oil set-
tles, and then check the oil level
through the engine oil level check
window located at the bottom-
right side of the crankcase.TIPThe engine oil should be between the
minimum and maximum level marks.
4. If the engine oil is below the mini-
mum level mark, add sufficient oil
of the recommended type to raise
it to the correct level.
To change the engine oil (with or
without oil filter cartridge replace-
ment)
1. Place the vehicle on a level sur-
face.
2. Start the engine, warm it up for
several minutes, and then turn it
off.
3. Place an oil pan under the engine
to collect the used oil.4. Remove the cowling by removing
the bolts.
5. Remove the engine oil filler cap,
the engine oil drain bolt and its
gasket to drain the oil from the
crankcase.1. Engine oil filler cap
2. Engine oil level check window
3. Maximum level mark
4. Minimum level mark
3
4
1 2
1. Cowling
2. Bolt
1. Engine oil drain bolt
2. Gasket
1
2
12
UB04E0E0.book Page 9 Wednesday, September 2, 2015 3:51 PM

Periodic maintenance and adjustment
6-11
6
10. Refill with the specified amount of
the recommended engine oil, and
then install and tighten the oil filler
cap.
TIPBe sure to wipe off spilled oil on any
parts after the engine and exhaust sys-
tem have cooled down.NOTICE
ECA11621
In order to prevent clutch slip-
page (since the engine oil also
lubricates the clutch), do not
mix any chemical additives. Do
not use oils with a diesel speci-
fication of “CD” or oils of a high-
er quality than specified. In
addition, do not use oils labeled
“ENERGY CONSERVING II” or
higher.
Make sure that no foreign mate-
rial enters the crankcase.11. Install the cowling by installing the
bolts.
12. Start the engine, and then let it idle
for several minutes while checking
it for oil leakage. If oil is leaking,
immediately turn the engine off
and check for the cause.
TIPAfter the engine is started, the engine
oil pressure warning light should go off.NOTICE
ECA20860
If the oil pressure warning light flick-
ers or remains on even if the oil level
is correct, immediately turn the en-
gine off and have a Yamaha dealer
check the vehicle.13. Turn the engine off, wait a few
minutes until the oil settles, and
then check the oil level and cor-
rect it if necessary.
1. Engine oil drain bolt
2. GasketTightening torque:
Engine oil drain bolt:
20 Nm (2.0 m·kgf, 14 ft·lbf)
Recommended engine oil:
See page 8-1.
Oil quantity:
Oil change:
1.80 L (1.90 US qt, 1.58 Imp.qt)
With oil filter removal:
2.10 L (2.22 US qt, 1.85 Imp.qt)
2
1
UB04E0E0.book Page 11 Wednesday, September 2, 2015 3:51 PM

Periodic maintenance and adjustment
6-12
6
EAU20071
CoolantThe coolant level should be checked
before each ride. In addition, the cool-
ant must be changed at the intervals
specified in the periodic maintenance
and lubrication chart.
EAU38176
To check the coolant level
1. Place the vehicle on a level sur-
face and hold it in an upright posi-
tion.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.2. Check the coolant level in the
coolant reservoir.TIPThe coolant should be between the
minimum and maximum level marks.
3. If the coolant is at or below the
minimum level mark, remove the
coolant reservoir cover by remov-
ing the bolts, remove the coolant
reservoir cap, and then add cool-
ant to the maximum level mark.
WARNING! Remove only the
coolant reservoir cap. Never at-
tempt to remove the radiator
cap when the engine is hot.
[EWA15162]
NOTICE: If coolant is not
available, use distilled water or
soft tap water instead. Do not
use hard water or salt water
since it is harmful to the engine.
If water has been used insteadof coolant, replace it with cool-
ant as soon as possible, other-
wise the cooling system will not
be protected against frost and
corrosion. If water has been
added to the coolant, have a
Yamaha dealer check the anti-
freeze content of the coolant as
soon as possible, otherwise the
effectiveness of the coolant will
be reduced.
[ECA10473]
1. Maximum level mark
2. Minimum level mark
3. Coolant reservoir
1
2
3
1. Bolt
2. Coolant reservoir cover
2
1
UB04E0E0.book Page 12 Wednesday, September 2, 2015 3:51 PM

Periodic maintenance and adjustment
6-19
6
EAU22274
Brake light switchesThe brake light, which is activated by
the brake pedal and brake lever,
should come on just before braking
takes effect. If necessary, adjust the
rear brake light switch as follows, but
the front brake light switch should be
adjusted by a Yamaha dealer.
Turn the rear brake light switch adjust-
ing nut while holding the rear brake
light switch in place. To make the
brake light come on earlier, turn the ad-
justing nut in direction (a). To make the
brake light come on later, turn the ad-
justing nut in direction (b).
EAU22393
Checking the front and rear
brake padsThe front and rear brake pads must be
checked for wear at the intervals spec-
ified in the periodic maintenance and
lubrication chart.
EAU22432
Front brake pads
Each front brake pad is provided with
wear indicator grooves, which allow
you to check the brake pad wear with-
out having to disassemble the brake.
To check the brake pad wear, check
the wear indicator grooves. If a brake
pad has worn to the point that the wearindicator grooves have almost disap-
peared, have a Yamaha dealer replace
the brake pads as a set.
EAU36721
Rear brake pads
Each rear brake pad is provided with
wear indicator grooves, which allow
you to check the brake pad wear with-
out having to disassemble the brake.
To check the brake pad wear, check
the wear indicator grooves. If a brake
pad has worn to the point that the wear
indicator grooves have almost disap-
peared, have a Yamaha dealer replace
the brake pads as a set.
1. Rear brake light switch
2. Rear brake light switch adjusting nut
(a)
(b)1
2
1. Brake pad wear indicator groove
1 1
1. Brake pad wear indicator groove
1
1
UB04E0E0.book Page 19 Wednesday, September 2, 2015 3:51 PM

Periodic maintenance and adjustment
6-30
6
If a fuse is blown, replace it as follows.1. Turn the key to “ ” and turn off
the electrical circuit in question.
2. Remove the blown fuse, and then
install a new fuse of the specified
amperage. WARNING! Do not
use a fuse of a higher amperage
rating than recommended to
avoid causing extensive dam-
age to the electrical system and
possibly a fire.
[EWA15132]
3. Turn the key to “ ” and turn on
the electrical circuit in question to
check if the device operates.
4. If the fuse immediately blows
again, have a Yamaha dealer
check the electrical system.
EAU68470
Replacing the headlight bulbThis model is equipped with halogen
bulb headlight. If a headlight bulb
burns out, have a Yamaha dealer re-
place it and, if necessary, adjust the
headlight beam.NOTICE
ECA17871
Headlight lens:
Do not affix any type of tinted film or
stickers to the headlight lens.
Do not use a headlight bulb of a
wattage higher than specified.
1. Fuse box
1. Ignition fuse
2. Signaling system fuse
3. Backup fuse (for clock)
4. Headlight fuse
5. Radiator fan motor fuse
6. Spare fuse
16
12345
Specified fuses:
Main fuse:
30.0 A
Headlight fuse:
15.0 A
Signaling system fuse:
7.5 A
Ignition fuse:
15.0 A
Radiator fan motor fuse:
7.5 A
Backup fuse:
7.5 A
UB04E0E0.book Page 30 Wednesday, September 2, 2015 3:51 PM

Periodic maintenance and adjustment
6-31
6
EAU44941
Auxiliary lightThis model is equipped with an LED-
type auxiliary light.
If the auxiliary light does not come on,
have a Yamaha dealer check it.
EAU24182
Tail/brake lightThis model is equipped with an LED-
type tail/brake light.
If the tail/brake light does not come on,
have a Yamaha dealer check it.
EAU62590
Replacing a turn signal light
bulb1. Remove the turn signal light lens
by removing the screw.
2. Remove the turn signal light bulb
socket (together with the bulb) by
turning it counterclockwise.
1. Auxiliary light
1 1
1. Turn signal light lens
2. Screw
1
2
UB04E0E0.book Page 31 Wednesday, September 2, 2015 3:51 PM

Periodic maintenance and adjustment
6-32
6 3. Remove the burnt-out bulb by
pulling it out.
4. Insert a new bulb into the socket.
5. Install the socket (together with
the bulb) by turning it clockwise.
6. Install the turn signal light lens by
installing the screw. NOTICE: Do
not overtighten the screw, oth-
erwise the lens may break.
[ECA11192]EAU62670
Replacing the license plate
light bulb1. Remove the mudguard by remov-
ing the quick fasteners.
2. Remove the rear fender lower
panel by removing the bolts and
screws.3. Remove the license plate light
bulb socket (together with the
bulb) by pulling it out.
4. Remove the burnt-out bulb by
pulling it out.
1. Turn signal light bulb socket
1
1. Mudguard
2. Quick fastener
1
2
1. Bolt
2. Screw
3. Rear fender lower panel
1. License plate light bulb
2. License plate light bulb socket
3
2
1
2
2 121
UB04E0E0.book Page 32 Wednesday, September 2, 2015 3:51 PM

Periodic maintenance and adjustment
6-35
6
EAU25081
Rear wheel
EAU62612
To remove the rear wheel
WARNING
EWA10822
To avoid injury, securely support the
vehicle so there is no danger of it
falling over.1. Remove the drive chain puller cap,
and then loosen the locknut and
drive chain slack adjusting nut on
each side of the swingarm.2. Loosen the axle nut.
3. Lift the rear wheel off the ground
according to the procedure on
page 6-33.
4. Remove the axle nut.
5. Push the wheel forward, and then
remove the drive chain from the
rear sprocket.
TIPThe drive chain does not need to be
disassembled in order to remove and
install the rear wheel.6. While supporting the brake caliper
and slightly lifting the wheel, pull
the wheel axle out.TIPA rubber mallet may be useful to tap
the wheel axle out.7. Remove the wheel. NOTICE: Do
not apply the brake after the
wheel and brake disc have been
removed, otherwise the brake
pads will be forced shut.
[ECA11073]
1. Wheel axle
2. Drive chain slack adjusting nut
3. Locknut
4. Drive chain puller cap
342
1
1. Axle nut
1
1. Wheel axle
2. Washer
1 2
UB04E0E0.book Page 35 Wednesday, September 2, 2015 3:51 PM

Periodic maintenance and adjustment
6-36
6 To install the rear wheel
1. Install the wheel and the brake cal-
iper bracket by inserting the wheel
axle from the left-hand side.
TIPMake sure that the slot in the
brake caliper bracket is fit over the
retainer on the swingarm.
Make sure that there is enough
space between the brake pads
before installing the wheel.2. Install the drive chain onto the rear
sprocket.
3. Install the axle nut.4. Lower the rear wheel so that it is
on the ground, and then put the
sidestand down.
5. Adjust the drive chain slack. (See
page 6-21.)
6. Tighten the axle nut, and then
tighten the locknuts to the speci-
fied torques.
7. Install the drive chain puller caps.
EAU25872
TroubleshootingAlthough 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 checking the fuel system, do
not smoke, and make sure there are
no open flames or sparks in the ar-
ea, including pilot lights from water
1. Retainer
2. Slot
1
2
Tightening torques:
Axle nut:
57 Nm (5.7 m·kgf, 41 ft·lbf)
Locknut:
16 Nm (1.6 m·kgf, 12 ft·lbf)
UB04E0E0.book Page 36 Wednesday, September 2, 2015 3:51 PM