2003 YAMAHA TW125 engine

3-12
EAU03720
Ignition circuit cut-off
system
The ignition circuit cut-off system
(comprising the sidestand switch,
clutch switch and neutral switch) has
the following functions.
8It prevents starting when the
transmission is in gear and the
sidestand is up, but the clutch
lever is not pulled.
8It prevents starting when the
transmission is in gear and the
clutch lever is pulled, but the
sidestand is still down.
8It cuts the running engine when
the transmission is in gear and
the sidestand is moved down.
Periodically check the operation of
the ignition circuit cut-off system
according to the following procedure.
EW000045
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If a malfunction is noted, have a
Yamaha dealer check the system
before riding.
INSTRUMENT AND CONTROL FUNCTIONS
3
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3-13
INSTRUMENT AND CONTROL FUNCTIONS
3
With the engine turned off:
1. Move the sidestand down.
2. Make sure that the engine stop switch is set to “
#”.
3. Turn the key to “ON”.
4. Shift the transmission into the neutral position.
5. Push the start switch.
Does the engine start?
The neutral switch may be defective.
The motorcycle should not be ridden until
checked by a Yamaha dealer.
With the engine still running:
6. Move the sidestand up.
7. Keep the clutch lever pulled.
8. Shift the transmission into gear.
9. Move the sidestand down.
Does the engine stall?
After the engine has stalled:
10. Move the sidestand up.
11. Keep the clutch lever pulled.
12. Push the start switch.
Does the engine start?
The sidestand switch may be defective.
The motorcycle should not be ridden until
checked by a Yamaha dealer.
The clutch switch may be defective.
The motorcycle should not be ridden until
checked by a Yamaha dealer.
NO
NOTE:
This check is most reliable if performed with
a warmed-up engine.
YES
YES NO
The system is OK. The motorcycle can be ridden.
YES NO
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4-1
EAU01114
PRE-OPERATION CHECKS
4The condition of a vehicle is the owner’s responsibility. Vital components can start to deteriorate quickly and unexpect-
edly, even if the vehicle remains unused (for example, as a result of exposure to the elements). Any damage, fluid leak-
age or loss of tire air pressure could have serious consequences. Therefore, it is very important, in addition to a thor-
ough visual inspection, to check the following points before each ride.
EAU03439
Pre-operation check listPre-operation check list
ITEM CHECKS PAGE
Fuel•Check fuel level in fuel tank.
•Refuel if necessary.
•Check fuel line for leakage.3-5–3-7
Engine oil•Check oil level in engine.
•If necessary, add recommended oil to specified level.
•Check vehicle for oil leakage.6-9–6-12
Front brake•Check operation.
•If soft or spongy, have Yamaha dealer bleed hydraulic system.
•Check lever free play.
•Adjust if necessary.
•Check fluid level in reservoir.
•If necessary, add recommended brake fluid to specified level.
•Check hydraulic system for leakage.3-5, 6-20, 6-23–6-25
Rear brake•Check operation.
•Check pedal free play.
•Adjust if necessary.3-5, 6-21–6-23
Clutch•Check operation.
•Lubricate cable if necessary.
•Check lever free play.
•Adjust if necessary.3-4, 6-19–6-20
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5-1
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OPERATION AND IMPORTANT RIDING POINTS
5
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8Become thoroughly familiar
with all operating controls and
their functions before riding.
Consult a Yamaha dealer
regarding any control or func-
tion that you do not thorough-
ly understand.
8Never start the engine or oper-
ate it in a closed area for any
length of time. Exhaust fumes
are poisonous, and inhaling
them can cause loss of con-
sciousness and death within a
short time. Always make sure
that there is adequate ventila-
tion.
8Before starting out, make sure
that the sidestand is up. If the
sidestand is not raised com-
pletely, it could contact the
ground and distract the opera-
tor, resulting in a possible loss
of control.
EAU04692
Starting a cold engine
In order for the ignition circuit cut-off
system to enable starting, one of the
following conditions must be met:
8The transmission is in the neutral
position.
8The transmission is in gear with
the clutch lever pulled and the
sidestand up.
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8Before starting the engine,
check the function of the igni-
tion circuit cut-off system
according to the procedure
described on page 3-13.
8Never ride with the sidestand
down.
1. Turn the fuel cock lever to “ON”.
2. Turn the key to “ON” and make
sure that the engine stop switch
is set to “#”.
3. Shift the transmission into the
neutral position.
NOTE:
When the transmission is in the neu-
tral position, the neutral indicator light
should be on, otherwise have a
Yamaha dealer check the electrical
circuit.
ONFUEL
RES
OFF
1ON
1. Arrow mark positioned over “ON”
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5-2
OPERATION AND IMPORTANT RIDING POINTS
54. Turn the starter (choke) on and
completely close the throttle.
(See page 3-8 for starter (choke)
operation.)
5. Start the engine by pushing the
start switch.
NOTE:
If the engine fails to start, release the
start switch, wait a few seconds, and
then try again. Each starting attempt
should be as short as possible to pre-
serve the battery. Do not crank the
engine more than 10 seconds on any
one attempt.
6. After starting the engine, move
the starter (choke) back halfway.
ECA00045
cC
For maximum engine life, never
accelerate hard when the engine is
cold!
7. When the engine is warm, turn
the starter (choke) off.
NOTE:
The engine is warm when it responds
normally to the throttle with the starter
(choke) turned off.
EAU01258
Starting a warm engine
Follow the same procedure as for
starting a cold engine with the excep-
tion that the starter (choke) is not
required when the engine is warm.1
1. Starter (choke)
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5-3
OPERATION AND IMPORTANT RIDING POINTS
5
EAU00423
Shifting
Shifting gears lets you control the
amount of engine power available for
starting off, accelerating, climbing
hills, etc.
The gear positions are shown in the
illustration.
NOTE:
To shift the transmission into the neu-
tral position, press the shift pedal
down repeatedly until it reaches the
end of its travel, and then slightly
raise it.
EC000048
cC
8Even with the transmission in
the neutral position, do not
coast for long periods of time
with the engine off, and do not
tow the motorcycle for long
distances. The transmission is
properly lubricated only when
the engine is running.
Inadequate lubrication may
damage the transmission.
8Always use the clutch while
changing gears to avoid dam-
aging the engine, transmis-
sion, and drive train, which are
not designed to withstand the
shock of forced shifting.
EAU02941
Recommended shift points
(for Switzerland only)
The recommended shift points during
acceleration are shown in the table
below.
NOTE:
When shifting down two gears at a
time, reduce the speed accordingly
(e.g., down to 35 km/h when shifting
from 4th to 2nd gear).
1
N5
4
3
2
1
1. Shift pedal
N. Neutral position
Shift point
(km/h)
1st→2nd
2nd→3rd
3rd→4th
4th→5th23
36
50
60
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5-4
OPERATION AND IMPORTANT RIDING POINTS
5
EAU04577
Tips for reducing fuel
consumption
Fuel consumption depends largely on
your riding style. Consider the follow-
ing tips to reduce fuel consumption:
8Turn the starter (choke) off as
soon as possible.
8Shift up swiftly, and avoid high
engine speeds during accelera-
tion.
8Do not rev the engine while shift-
ing down, and avoid high engine
speeds with no load on the
engine.
8Turn the engine off instead of let-
ting it idle for an extended length
of time (e.g., in traffic jams, at
traffic lights or at railroad cross-
ings).
EAU00436
Engine break-in
There is never a more important peri-
od in the life of your engine than the
period between 0 and 1,000 km. For
this reason, you should read the fol-
lowing material carefully.
Since the engine is brand new, do
not put an excessive load on it for the
first 1,000 km. The various parts in
the engine wear and polish them-
selves to the correct operating clear-
ances. During this period, prolonged
full-throttle operation or any condition
that might result in engine overheat-
ing must be avoided.
EAU04398
0–500 km
Avoid prolonged operation above 1/3
throttle.
500–1,000 km
Avoid prolonged operation above 1/2
throttle.
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After 1,000 km of operation, the
engine oil must be changed, and
the oil filter element and the oil
strainer cleaned.
1,000 km and beyond
The vehicle can now be operated
normally.
EC000049
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If any engine trouble should occur
during the engine break-in period,
immediately have a Yamaha dealer
check the vehicle.
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5-5
OPERATION AND IMPORTANT RIDING POINTS
5
EAU00457
Parking
When parking, stop the engine,
remove the key from the main switch,
and then turn the fuel cock lever to
“OFF”.
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8Since the engine and exhaust
system can become very hot,
park in a place where pedestri-
ans or children are not likely
to touch them.
8Do not park on a slope or on
soft ground, otherwise the
motorcycle may overturn.
RES
ONFUEL
OFF
1
1. Arrow mark positioned over “OFF”
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