2004 YAMAHA AEROX50 check engine

PERIODIC MAINTENANCE AND MINOR REPAIR
6
EAU01651
Checking the spark plug
The spark plug is an important engine
component, which should be checked
periodically, preferably by a Yamaha
dealer. Since heat and deposits will
cause any spark plug to slowly erode,
it should be removed and checked in
accordance with the periodic mainte-
nance and lubrication chart. In addition,
the condition of the spark plug can
reveal the condition of the engine.
The porcelain insulator around the
center electrode of the spark plug
should be a medium-to-light tan (the
ideal color when the scooter is ridden
normally). If the spark plug shows a
distinctly different color, the engine
could be defective. Do not attempt to
diagnose such problems yourself.
Instead, have a Yamaha dealer check
the scooter.
If the spark plug shows signs of
electrode erosion and excessive carbon
or other deposits, it should be replaced.Specified spark plug:
BR8HS (NGK)
Before installing a spark plug, the spark
plug gap should be measured with a
wire thickness gauge and, if necessary,
adjusted to specification.
Spark plug gap:
0.5 — 0.7 mm
Clean the surface of the spark plug
gasket and its mating surface, and then
wipe off any grime from the spark plug
threads.
a
ZAUM0037
a Spark plug gap
Tightening torque:
Spark plug:
20 Nm (2.0 m
•kg)
NOTE :
If 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.
6-6

PERIODIC MAINTENANCE AND MINOR REPAIR
6
EWA00062
•Make sure that no foreign
material enters the final trans-
mission case.
•Make sure that no oil gets on
the tire or wheel.
7. Check the final transmission case
for oil leakage. If oil is leaking,
check for the cause.
WARNING
EAU04228
Final transmission oil
The final transmission case must be
checked for oil leakage before each
ride. If any leakage is found, have a
Yamaha dealer check and repair the
scooter. In addition, the final transmis-
sion oil must be changed as follows at
the intervals specified in the periodic
maintenance and lubrication chart.
1. Start the engine, warm it up by
riding the scooter for several mi-
nutes, and then stop the engine.2. Place the scooter on the
centerstand.
3. Place an oil pan under the final
transmission case to collect the
used oil.
4. Remove the oil filler cap and drain
bolt to drain the oil from the final
transmission case.
5. Install the final transmission oil
drain bolt, and then tighten it to
the specified torque.
Tightening torque:
Final transmission oil drain bolt:
18 Nm (1.8 m
•kgf)
6. Add the specified amount of the
recommended final transmission
oil, and then install and tighten the
oil filler cap.
Recommended final transmission
oil:
See page 8-1.
Oil quantity:
0.13 L
12ZAUM0273
1. Final transmission oil drain bolt
2. Oil filler cap
6-7

PERIODIC MAINTENANCE AND MINOR REPAIR
6
EC000080
•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 instead
of coolant, replace it with
coolant as soon as possible,
otherwise the engine may not
be sufficiently cooled and the
cooling system will not be
protected against frost and cor-
rosion.
•If water has been added to the
coolant, have a Yamaha dealer
check the antifreeze content of
the coolant as soon as possi-
ble, otherwise the effectiveness
of the coolant will be reduced.
EW000067
Never attempt to remove the radiator
cap when the engine is hot.
CAUTION:
WARNING
EAU01808*
Coolant
To check the coolant level
1. Place the scooter on a level sur-
face and hold it in an upright po-
sition.
NOTE :
•The coolant level must be
checked on a cold engine since
the level varies with engine
temperature.
•Make sure that the scooter is
positioned straight up when
checking the coolant level. A slight
tilt to the side can result in a false
reading.
2. Remove cowling A. (See page
6-5 for cowling removal and ins-
tallation procedures.)3. Check the coolant level in the
coolant reservoir.
NOTE :
The coolant should be between the
minimum and maximum level marks.
4. If the coolant is at or below the
minimum level mark, open the
reservoir cap, add coolant to the
maximum level mark, and then
close the reservoir cap.
Coolant reservoir capacity:
0.25 L

1
ZAUM0274
1. Coolant tank cap
6-8

PERIODIC MAINTENANCE AND MINOR REPAIR
6Observe these precautions:
•When checking the fluid level,
make sure that the top of the
master cylinder is level by turning
the handlebars.
•Use only the recommended
quality brake fluid, otherwise the
rubber seals may deteriorate,
causing leakage and poor braking
performance.
Recommended brake fluid:
DOT 4
NOTE :
If DOT 4 is not available, DOT 3 can be
used.
•Refill with the same type of brake
fluid. Mixing fluids may result in a
harmful chemical reaction and
lead to poor braking performance.
•Be careful that water does not
enter the master cylinder when
refilling. Water will significantly
lower the boiling point of the fluid
and may result in vapor lock.
•Brake fluid may deteriorate
painted surfaces or plastic parts.
Always clean up spilled fluid
immediately.
•As the brake pads wear, it is nor-
mal for the brake fluid level to
gradually go down. However, if the
brake fluid level goes down
suddenly, have a Yamaha dealer
check the cause.
EAUM0008*
Changing the brake fluid
Have a Yamaha dealer change the
brake fluid at the intervals specified in
the periodic maintenance and
lubrication chart. In addition, have the
brake hoses replaced every four years
or whenever there are damaged or
leaking.
6-15
EAU00774
Adjusting the Autolube pump
The Autolube pump is a vital and
sophisticated component of the engine,
which must be adjusted by a Yamaha
dealer at the intervals specified in the
periodic maintenance and lubrication
chart.

PERIODIC MAINTENANCE AND MINOR REPAIR
6
ZAUM0061
EAU03118
Lubricating the front and rear
brake levers
The pivoting points of the front and rear
brake levers must be lubricated at the
intervals specified in the periodic main-
tenance and lubrication chart.
Recommended lubricant:
Lithium-soap-based grease
(all-purpose grease)
ZAUM0062
EAU04123
Checking and lubricating the
centerstand
The operation of the centerstand should
be checked before each ride, and the
pivots and metal-to-metal contact sur-
faces should be lubricated if necessary.
EWA00055
If the centerstand does not move up
and down smoothly, have a Yamaha
dealer check or repair it.
Recommended lubricant:
Lithium-soap-based grease
(all-purpose grease)
WARNING
6-16
EAU02962
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 cables
and cable ends should be lubricated if
necessary. If a cable is damaged or does
not move smoothly, have a Yamaha dea-
ler check or replace it.
Recommended lubricant:
Engine oil
EW000112
Damage to the outer sheath may
interfere with proper cable operation
and will cause the inner cable to rust.
Replace a damaged cable as soon
as possible to prevent unsafe con-
ditions.
WARNING

PERIODIC MAINTENANCE AND MINOR REPAIR
6
EAU02939
Checking the front fork
The condition and operation of the front
fork must be checked as follows at the
intervals specified in the periodic main-
tenance and lubrication chart.
To check the condition
EW000115
Securely support the scooter so that
there is no danger of it falling over.
Check the inner tubes for scratches,
damage and excessive oil leakage.
WARNINGTo check the operation
1. Place the scooter on a level sur-
face and hold it in an upright po-
sition.
2. While applying the front brake,
push down hard on the
handlebars several times to check
if the front fork compresses and
rebounds smoothly.
EC000098
If any damage is found or the front
fork does not operate smoothly, have
a Yamaha dealer check or repair it.
CAUTION:
EAU00794
Checking the steering
Worn or loose steering bearings may
cause danger. Therefore, the operation
of the steering must be checked as
follows at the intervals specified in the
periodic maintenance and lubrication
chart.
1. Place a stand under the engine
to raise the front wheel off the
ground.
EW000115
Securely support the scooter so that
there is no danger of it falling over.
WARNING
6-17
ZAUM0296ZAUM0297

PERIODIC MAINTENANCE AND MINOR REPAIR
6
EAU03363
Troubleshooting charts
Starting problems or poor engine performance
EW000125
Keep away open flames and do not smoke while checking or working on the fuel system.
WARNING
Check the fuel level in
the fuel tank.
1. FuelThere is enough fuel.
There is no fuel.Check the compression.
Supply fuel.
Operate the electric starter.
2. CompressionThere is compression.
There is no compression.Check the ignition.
Have a Yamaha dealer
check the vehicle.
Remove the spark plugs
and check the electrodes.
3. IgnitionWet
DryWipe off with a dry cloth and correct the
spark plug gaps, or replace the spark plugs.
Have a Yamaha dealer check the vehicle.The engine does not start.
Check the battery.Open the throttle halfway and operate
the electric starter.
Operate the electric starter.
4. BatteryThe engine turns over
quickly.
The engine turns over
slowly.The battery is good.
Check the electrolyte and battery
lead connections, and charge the
battery if necessary.The engine does not start.
Have a Yamaha dealer
check the vehicle.
The engine does not start.
Check the compressoin.
6-23

PERIODIC MAINTENANCE AND MINOR REPAIR
6 Engine overheating
EW000070
•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 hissing
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.
WARNING
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 NOTE.)
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.
6-24