2016 YAMAHA MT-25 spark plugs

Table of contentsSafety 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 ...................... 3-10
Clutch lever .................................. 3-11
Shift pedal .................................... 3-12
Brake lever.................................... 3-12
Brake pedal .................................. 3-12
Fuel tank cap ................................ 3-13
Fuel ............................................... 3-13
Fuel tank breather hose and
overflow hose ............................ 3-15
Catalytic converter ....................... 3-15
Seats ............................................ 3-16
Helmet holders ............................. 3-17
Storage compartment .................. 3-18
Adjusting the shock absorber
assembly ................................... 3-18
Luggage strap holders ................. 3-19
Sidestand ..................................... 3-19
Ignition circuit cut-off system ....... 3-20For your safety – pre-operation
checks............................................... 4-1
Operation and important riding
points................................................. 5-1
Starting the engine .......................... 5-1
Shifting ............................................ 5-2
Tips for reducing fuel
consumption ................................ 5-3
Engine break-in ............................... 5-3
Parking ............................................ 5-4
Periodic maintenance and
adjustment........................................ 6-1
Owner’s tool kit ............................... 6-1
Periodic maintenance chart for
the emission control system ........ 6-3
General maintenance and
lubrication chart ........................... 6-4
Checking the spark plugs ............... 6-8
Engine oil and oil filter cartridge...... 6-9
Coolant.......................................... 6-12
Replacing the air filter element
and cleaning the check hose..... 6-13
Checking the throttle grip
free play ..................................... 6-15
Valve clearance ............................. 6-15
Tires .............................................. 6-15
Cast wheels................................... 6-17
Adjusting the clutch lever
free play ..................................... 6-17Checking the brake lever
free play..................................... 6-18
Brake light switches ..................... 6-19
Checking the front and rear
brake pads ................................ 6-19
Checking the brake fluid level ...... 6-20
Changing the brake fluid .............. 6-21
Drive chain slack........................... 6-21
Cleaning and lubricating the
drive chain ................................. 6-23
Checking and lubricating the
cables ........................................ 6-24
Checking and lubricating the
throttle grip and cable ............... 6-24
Checking and lubricating the
brake and shift pedals............... 6-24
Checking and lubricating the
brake and clutch levers ............. 6-25
Checking and lubricating the
sidestand................................... 6-26
Lubricating the swingarm
pivots......................................... 6-26
Checking the front fork ................. 6-26
Checking the steering................... 6-27
Checking the wheel bearings ....... 6-27
Battery .......................................... 6-28
Replacing the fuses ...................... 6-29
Replacing the headlight bulb ........ 6-30
Auxiliary light ................................ 6-31
Tail/brake light .............................. 6-31UB04E0E0.book Page 1 Wednesday, September 2, 2015 3:51 PM

Periodic maintenance and adjustment
6-3
6
EAU46862
TIPThe annual checks must be performed every year, except if a kilometer-based maintenance, or for the UK, a
mileage-based maintenance, is performed instead.
From 50000 km (30000 mi), repeat the maintenance intervals starting from 10000 km (6000 mi).
Items marked with an asterisk should be performed by a Yamaha dealer as they require special tools, data and tech-
nical skills.
EAU46911
Periodic maintenance chart for the emission control systemNO. ITEM CHECK OR MAINTENANCE JOBODOMETER READING
ANNUAL
CHECK 1000 km
(600 mi)10000 km
(6000 mi)20000 km
(12000 mi)30000 km
(18000 mi)40000 km
(24000 mi)
1*Fuel line• Check fuel hoses for cracks or
damage.√√√√√
2*Spark plugs• Check condition.
• Clean and regap.√√
• Replace.√√
3*Va l ve s• Check valve clearance.
•Adjust.Every 40000 km (24000 mi)
4*Fuel injection sys-
tem• Adjust synchronization.√√√√√
5*Muffler and ex-
haust pipe• Check the screw clamp(s) for
looseness.√√√√√
6*Air induction sys-
tem• Check the air cut-off valve, reed
valve, and hose for damage.
• Replace any damaged parts if
necessary.√√√√√
UB04E0E0.book Page 3 Wednesday, September 2, 2015 3:51 PM

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)
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Periodic maintenance and adjustment
6-38
6
EAU42505
Troubleshooting chartsStarting problems or poor engine performance
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.
Remove the spark plugs
and check the electrodes.3. Ignition
Wipe off with a dry cloth and correct the
spark plug gaps, or replace the spark plugs.
Have a Yamaha dealer check the vehicle.
Operate the electric starter.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.
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 engine does not start.
Check the ignition.
The battery is good.Check the battery lead connections,
and have a Yamaha dealer charge
the battery if necessary.
DryWet
Operate the electric starter.
UB04E0E0.book Page 38 Wednesday, September 2, 2015 3:51 PM

Motorcycle care and storage
7-4
7
EAU26183
StorageShort-term
Always store your motorcycle in a cool,
dry place and, if necessary, protect it
against dust with a porous cover. Be
sure the engine and the exhaust sys-
tem are cool before covering the mo-
torcycle.NOTICE
ECA10811
Storing the motorcycle in a
poorly ventilated room or cover-
ing it with a tarp, while it is still
wet, will allow water and humid-
ity to seep in and cause rust.
To prevent corrosion, avoid
damp cellars, stables (because
of the presence of ammonia)
and areas where strong chemi-
cals are stored.Long-term
Before storing your motorcycle for sev-
eral months:
1. Follow all the instructions in the
“Care” section of this chapter.2. Fill up the fuel tank and add fuel
stabilizer (if available) to prevent
the fuel tank from rusting and the
fuel from deteriorating.
3. Perform the following steps to
protect the cylinders, piston rings,
etc. from corrosion.
a. Remove the spark plug caps
and spark plugs.
b. Pour a teaspoonful of engine
oil into each spark plug bore.
c. Install the spark plug caps onto
the spark plugs, and then
place the spark plugs on the
cylinder head so that the elec-
trodes are grounded. (This will
limit sparking during the next
step.)
d. Turn the engine over several
times with the starter. (This will
coat the cylinder walls with oil.)
WARNING! To prevent dam-
age or injury from sparking,
make sure to ground the
spark plug electrodes while
turning the engine over.
[EWA10952]
e. Remove the spark plug caps
from the spark plugs, and then
install the spark plugs and the
spark plug caps.
4. Lubricate all control cables and
the pivoting points of all levers and
pedals as well as of the side-
stand/centerstand.
5. Check and, if necessary, correct
the tire air pressure, and then lift
the motorcycle so that both of its
wheels are off the ground. Alterna-
tively, turn the wheels a little every
month in order to prevent the tires
from becoming degraded in one
spot.
6. Cover the muffler outlet with a
plastic bag to prevent moisture
from entering it.
7. Remove the battery and fully
charge it. Store it in a cool, dry
place and charge it once a month.
Do not store the battery in an ex-
cessively cold or warm place [less
than 0 °C (30 °F) or more than 30
°C (90 °F)]. For more information
on storing the battery, see page
6-28.
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10-1
10
Index
AAir filter element and check hose,
replacing and cleaning ....................... 6-13
Auxiliary light ........................................ 6-31BBattery .................................................. 6-28
Brake and clutch levers,
checking and lubricating .................... 6-25
Brake and shift pedals,
checking and lubricating .................... 6-24
Brake fluid, changing............................ 6-21
Brake fluid level, checking.................... 6-20
Brake lever............................................ 3-12
Brake lever free play, checking ............ 6-18
Brake light switches ............................. 6-19
Brake pedal .......................................... 3-12CCables, checking and lubricating ......... 6-24
Care ........................................................ 7-1
Catalytic converter ............................... 3-15
Clutch lever........................................... 3-11
Clutch lever free play, adjusting ........... 6-17
Coolant ................................................. 6-12DDimmer switch...................................... 3-11
Drive chain, cleaning and lubricating ... 6-23
Drive chain slack .................................. 6-21EEngine break-in ...................................... 5-3
Engine oil and oil filter cartridge ............. 6-9
Engine serial number .............................. 9-1
Engine stop switch ............................... 3-11
Engine trouble warning light ................... 3-3
FFront and rear brake pads, checking ... 6-19
Front fork, checking ............................. 6-26
Fuel ...................................................... 3-13
Fuel consumption, tips for reducing ...... 5-3
Fuel tank breather hose and
overflow hose..................................... 3-15
Fuel tank cap........................................ 3-13
Fuses, replacing ................................... 6-29HHandlebar switches ............................. 3-10
Headlight bulb, replacing ..................... 6-30
Helmet holders ..................................... 3-17
High beam indicator light ....................... 3-2
Horn switch .......................................... 3-11IIdentification numbers ........................... 9-1
Ignition circuit cut-off system .............. 3-20
Indicator lights and warning lights ......... 3-2LLicense plate light bulb, replacing ....... 6-32
Luggage strap holders ......................... 3-19MMain switch/steering lock ...................... 3-1
Maintenance and lubrication,
periodic ................................................ 6-4
Maintenance, emission control
system ................................................. 6-3
Matte color, caution ............................... 7-1
Model label............................................. 9-1
Multi-function meter unit ........................ 3-4NNeutral indicator light ............................. 3-2
OOil pressure warning light ....................... 3-2PParking.................................................... 5-4
Part locations.......................................... 2-1
Pass switch........................................... 3-11SSafety information................................... 1-1
Seats ..................................................... 3-16
Shifting.................................................... 5-2
Shift pedal............................................. 3-12
Shift timing indicator light ....................... 3-3
Shock absorber assembly, adjusting ... 3-18
Sidestand.............................................. 3-19
Sidestand, checking and lubricating .... 6-26
Spark plugs, checking ............................ 6-8
Specifications ......................................... 8-1
Starting the engine ................................. 5-1
Start switch ........................................... 3-11
Steering, checking ................................ 6-27
Storage ................................................... 7-4
Storage compartment........................... 3-18
Supporting the motorcycle ................... 6-33
Swingarm pivots, lubricating ................ 6-26TTail/brake light ...................................... 6-31
Throttle grip and cable,
checking and lubricating .................... 6-24
Throttle grip free play, checking ........... 6-15
Tires ...................................................... 6-15
Tool kit .................................................... 6-1
Troubleshooting .................................... 6-36
Troubleshooting charts ......................... 6-38
Turn signal indicator light ....................... 3-2
UB04E0E0.book Page 1 Wednesday, September 2, 2015 3:51 PM