engine YAMAHA TW125 2003 User Guide

4-1
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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
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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).
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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.
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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.
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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
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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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6-4
PERIODIC MAINTENANCE AND MINOR REPAIR
6EAU03541
NOTE:
8The air filter needs more frequent service if you are riding in unusually wet or dusty areas.
8Hydraulic brake service
9Regularly check and, if necessary, correct the brake fluid level.
9Every two years replace the internal components of the brake master cylinder and caliper, and change the brake
fluid.
9Replace the brake hoses every four years and if cracked or damaged.
21*Carburetor•Check starter (choke) operation.
•Adjust engine idling speed.√√√√√ √
22 Engine oil•Change.
•Check oil level and vehicle for oil leakage.√√√√√ √
23 Engine oil filter element•Clean.√√√
24
*Engine oil strainer•Clean.√
25
*Front and rear brake
switches•Check operation.√√√√√ √
26 Moving parts and cables•Lubricate.√√√√ √
27
*Throttle grip housing
and cable•Check operation and free play.
•Adjust the throttle cable free play if necessary.
•Lubricate the throttle grip housing and cable.√√√√ √
28
*Lights, signals and
switches•Check operation.
•Adjust headlight beam.√√√√√ √ NO. ITEM CHECK OR MAINTENANCE JOBODOMETER READING (× 1,000 km)
ANNUAL
CHECK
1 6 12 18 24
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6-7
PERIODIC MAINTENANCE AND MINOR REPAIR
6
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Checking the spark plug
The spark plug is an important
engine component, which is easy to
check. Since heat and deposits will
cause any spark plug to slowly erode,
the spark plug should be removed
and checked in accordance with the
periodic maintenance and lubrication
chart. In addition, the condition of the
spark plug can reveal the condition of
the engine.To remove the spark plug
1. Remove the spark plug cap.
1
1. Spark plug cap
2. Remove the spark plug as
shown, with the spark plug
wrench included in the owner’s
tool kit.
1
1. Spark plug wrench
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6-8
PERIODIC MAINTENANCE AND MINOR REPAIR
6 To check the spark plug
1. Check that the porcelain insula-
tor around the center electrode
of the spark plug is a medium-to-
light tan (the ideal color when the
motorcycle is ridden normally).
NOTE:
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
motorcycle.
2. Check the spark plug for elec-
trode erosion and excessive car-
bon or other deposits, and
replace it if necessary.To install the spark plug
1. Measure the spark plug gap with
a wire thickness gauge and, if
necessary, adjust the gap to
specification.
2. Clean the surface of the spark
plug gasket and its mating sur-
face, and then wipe off any grime
from the spark plug threads.
3. Install the spark plug with the
spark plug wrench, and then
tighten it to the specified torque.
a
a. Spark plug gap
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.
4. Install the spark plug cap.
Spark plug gap:
0.6–0.7 mm
Tightening torque:
Spark plug:
17.5 Nm (1.75 m·kgf)
Specified spark plug:
DR8EA (NGK)
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6-9
PERIODIC MAINTENANCE AND MINOR REPAIR
6
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Engine oil and oil filter
element
The engine oil level should be
checked before each ride. In addition,
the oil must be changed and the oil
filter element cleaned at the intervals
specified in the periodic maintenance
and lubrication chart.
To check the engine oil level
1. Place the motorcycle on a level
surface and hold it in an upright
position.
NOTE:
Make sure that the motorcycle is
positioned straight up when checking
the oil level. 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
settles, and then check the oil
level through the check window
located at the bottom-right side
of the crankcase.
NOTE:
The engine oil should be between the
minimum and maximum level marks.
4. If the engine oil is below the min-
imum level mark, add sufficient
oil of the recommended type to
raise it to the correct level.
2
3 1
1. Engine oil level check window
2. Maximum level mark
3. Minimum level mark
To change the engine oil (with or
without oil filter element cleaning)
1. Start the engine, warm it up for
several minutes, and then turn it
off.
2. Place an oil pan under the
engine to collect the used oil.
3. Remove the engine oil filler cap
and drain bolt to drain the oil
from the crankcase.
1
1. Engine oil filler cap
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