2012 YAMAHA MT-03 engine

PERIODIC MAINTENANCE AND MINOR REPAIR
1. Air filter element
ECA10480CAUTION:
●Make sure that the air filter ele-
ment is properly seated in the
air filter case.
●The engine should never be op-
erated without the air filter ele-
ment installed, otherwise the
piston(s) and/or cylinder(s) may
become excessively worn.
4. Install the air filter case cover by
installing the screws.
To clean the air filter check hoses
1. Air filter check hose (case cover)
1. Check the hoses shown for accu-
mulated dirt, water or oil.
2. If dirt, water or oil is visible, re-
move the hose, clean it, and then
install it in its original position.
EAU34300
Adjusting the engine idling
speed
1. Idle adjusting screw
The engine idling speed must be
checked and, if necessary, adjusted
as follows at the intervals specified in
the periodic maintenance and lubrica-
tion chart.
The engine should be warm before
making this adjustment.
NOTE:
The engine is warm when it quickly re-
sponds to the throttle.
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PERIODIC MAINTENANCE AND MINOR REPAIR
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).
NOTE:
If the specified idling speed cannot be
obtained as described above, have a
Yamaha dealer make the adjustment.
EAU21381
Checking the throttle cable
free play
1. Throttle cable free play
The throttle cable free play should
measure 3.0-5.0 mm (0.12-0.20 in) at
the throttle grip. Periodically check the
throttle cable free play and, if neces-
sary, have a Yamaha dealer adjust it.
6-15
Engine idling speed:
1300-1500 r/min
1400-1600 r/min (EU3 version)
EAU21401
Valve clearance
The valve clearance changes with
use, resulting in improper air-fuel mix-
ture and/or engine noise. To prevent
this from occurring, the valve clear-
ance must be adjusted by a Yamaha
dealer at the intervals specified in the
periodic maintenance and lubrication
chart.

PERIODIC MAINTENANCE AND MINOR REPAIR
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1. Axle nut
2. Drive chain slack adjusting bolt
3. Locknut
4. Alignment marks
ECA10570
CAUTION:
Improper drive chain slack will
overload the engine as well as oth-
er vital parts of the motorcycle and
can lead to chain slippage or break-
age. To prevent this from occurring,
keep the drive chain slack within
the specified limits.
Tightening torques:
Locknut:
16 Nm (1.6 m·kgf, 11 ft·lbf)
Axle nut:
150 Nm (15.0 m·kgf, 108 ft·lbf)
EAU23022
Cleaning and lubricating
the drive chain
The 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.
ECA10581CAUTION:
The drive chain must be lubricated
after washing the motorcycle and
riding in the rain.
1. Clean the drive chain with
kerosene and a small soft brush.
ECA11120CAUTION:
To prevent damaging the O-rings,
do not clean the drive chain with
steam cleaners, high-pressure
washers or inappropriate solvents. 3. Tighten the locknuts, then the
axle nut to their specified torques.

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PERIODIC MAINTENANCE AND MINOR REPAIR
6-25
2. Wipe the drive chain dry.
3. Thoroughly lubricate the drive
chain with a special O-ring chain
lubricant.
ECA11110CAUTION:
Do not use engine oil or any other
lubricants for the drive chain, as
they may contain substances that
could damage the O-rings.
EAU23100
Checking and lubricating
the cables
The operation of all control cables and
the condition of the cables should be
checked before each ride, and the ca-
bles and cable ends should be lubri-
cated if necessary. If a cable is dam-
aged or does not move smoothly,
have a Yamaha dealer check or re-
place it.
Recommended lubricant:
Engine oil
EWA10720
WARNING0
Damage to the outer sheath may in-
terfere with proper cable operation
and will cause the inner cable to
rust. Replace a damaged cable as
soon as possible to prevent unsafe
conditions.
EAU23111
Checking and lubricating
the throttle grip and cable
The operation of the throttle grip
should be checked before each ride.
In addition, the cable should be lubri-
cated at the intervals specified in the
periodic maintenance chart.

PERIODIC MAINTENANCE AND MINOR REPAIR
ECA10590CAUTION:
If any damage is found or the front
fork does not operate smoothly,
have a Yamaha dealer check or re-
pair it.
EAU23280
Checking the steering
Worn or loose steering bearings may
cause danger. Therefore, the opera-
tion of the steering must be checked
as follows at the intervals specified in
the periodic maintenance and lubrica-
tion chart.
1. Place a stand under the engine to
raise the front wheel off the
ground.
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EWA10750
WARNING0
Securely support the motorcycle so
that there is no danger of it falling
over.
2. Hold the lower ends of the front
fork legs and try to move them for-
ward and backward. If any free
play can be felt, have a Yamaha
dealer check or repair the steering.

PERIODIC MAINTENANCE AND MINOR REPAIR
EAUB1410
Replacing the license plate
light bulb
1. Reinforcement plate
2. Bulb socket
3. License plate light bulb
1. Remove the reinforcement plate
by removing the bolts and nuts.
2. Remove the license plate light
bulb socket by pulling it out.
NOTE:
When removing the license plate light
bulb socket, be careful not to pull too
hard.
EAU24350
Supporting the motorcycle
Since this model is not equipped with
a centerstand, follow these precau-
tions when removing the front and rear
wheel or performing other mainte-
nance requiring the motorcycle to
stand upright. Check that the motorcy-
cle is in a stable and level position be-
fore starting any maintenance. A
strong wooden box can be placed un-
der the engine for added stability.
To service the front wheel
1. Stabilize the rear of the motorcy-
cle by using a motorcycle stand
or, if an additional motorcycle
stand is not available, by placing
a jack under the frame in front of
the rear wheel.
2. Raise the front wheel off the
ground by using a motorcycle
stand.
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3. Remove the defective bulb by
pulling it out of the socket.
4. Insert a new bulb into the socket.
5. Install the bulb socket by pushing
it in.
6. Install the reinforcement plate in
the original position, and then
tighten bolts and nuts to the spec-
ified torque.
Tightening torque:
Reinforcement plate nut:
7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Reinforcement plate bolt (centre):
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Reinforcement plate bolt (upper):
10 Nm (1.0 m·kgf, 7.2 ft·lbf)

PERIODIC MAINTENANCE AND MINOR REPAIR
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EAU25921Troubleshooting charts
Starting problems or poor engine performance
WARNING0
Keep away open flames and do not smoke while checking or working on the fuel system.
1. Fuel
2. Compression
3. Ignition
4. Battery
Check the fuel level in the
fuel tank.
Operate the electric
starter.
Remove the spark plug
and check the electrodes.
Operate the electric
starter.
There is enough
fuel.
There is
compression.
Wet.
The engine turns
over quickly.
There is no fuel.
There is no
compression.
Dry.
The engine turns
over slowly.
Check the
compression.
Check the ignition.
Wipe off with a dry cloth and correct
the spark plug gap, or replace the
spark plug.
The battery is good.
Have a Yamaha dealer check the
vehicle.
Check the battery lead connections,
and charge the battery if necessary.
Open the throttle halfway and
operate the electric starter.
The engine does not start.
Check the battery.
The engine does
not start. Have a
Yamaha dealer
check the vehicle.
Supply fuel.
Have a Yamaha dealer check
the vehicle.
The engine does not start.
Check the compression.
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-41
Engine overheatingEWA10400
WARNING0
●Do not remove the radiator cap when the engine and radiator are hot. Scalding hot fluid and steam may be
blown out under pressure, which could cause serious injury. Be sure to wait until the engine has cooled.
●After removing the radiator cap retaining bolt, place a thick rag, like a towel, over the radiator cap, and then
slowly rotate the cap counterclockwise to the detent to allow any residual pressure to escape. When the hiss-
ing sound has stopped, press down on the cap while turning it counterclockwise, and then remove the cap.
NOTE:
If coolant is not available, tap water can be temporarily used instead, provided that it is changed to the recommended
coolant as soon as possible.
Wait until the
engine has cooled.Check the coolant level
in the reservoir and radiator.
The coolant level is low.
Check the cooling
system for leakage.
The coolant level
is OK.
There is
leakage.
There is no
leakage.
Have a Yamaha dealer check
and repair the cooling system.
Start the engine. If the engine overheats again, have
a Yamaha dealer check and repair the cooling system.
Add coolant. (See NOTE.)