2002 YAMAHA DT125R engine

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 list
ITEM CHECKS PAGE
Fuel•Check fuel level in fuel tank.
•Refuel if necessary.
•Check fuel line for leakage.3-5–3-7
2-stroke engine oil•Check oil level in oil tank.
•If necessary, add recommended oil to specified level.
•Check vehicle for oil leakage.3-8
Transmission oil•Check oil level in transmission case.
•If necessary, add recommended oil to specified level.6-10–6-12
Coolant•Check coolant level in reservoir.
•If necessary, add recommended coolant to specified level.
•Check cooling system for leakage.6-12–6-15
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, 6-23, 6-24–6-26
Rear brake•Check operation.
•If soft or spongy, have Yamaha dealer bleed hydraulic system.
•Check fluid level in reservoir.
•If necessary, add recommended brake fluid to specified level.
•Check hydraulic system for leakage.3-5, 6-23–6-26
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5-1
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OPERATION AND IMPORTANT RIDING POINTS
5
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w8Become 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 engineIn 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.
EW000054
w8Before starting the engine,
check the function of the igni-
tion circuit cut-off system
according to the procedure
described on page 3-17.
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.
ON
FUEL
RES
OFF
1
ON
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 3-10 for starter
(choke) operation.)
5. Start the engine by pushing the
kickstarter lever down.
6. After starting the engine, move
the starter (choke) lever back
halfway.
ECA00045
cCFor 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 engineFollow 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.
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ShiftingShifting 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.
6
5
4
3
2
1 N
1
1. Shift pedal
N. Neutral position
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5-3
OPERATION AND IMPORTANT RIDING POINTS
5
EC000048
cC8Even 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.
EAU02937
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 5th to 3rd gear).
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Tips for reducing fuel
consumptionFuel consumption depends largely on
your riding style. Consider the follow-
ing tips to reduce fuel consumption:
8Thoroughly warm up the engine.
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).
Shift point
(km/h)
1st→2nd
2nd→3rd
3rd→4th
4th→5th
5th→6th20
30
40
50
60
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5-4
OPERATION AND IMPORTANT RIDING POINTS
5
EAU00436
Engine break-inThere 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
8Avoid prolonged operation above
6,000 r/min.
8After every hour of operation,
stop the engine, and then let it
cool for five to ten minutes.
8Vary the engine speed from time
to time. Do not operate the
engine at one set throttle posi-
tion.
500–1,000 km
8Avoid prolonged operation above
7,000 r/min.
8Rev the engine freely through
the gears, but do not use full
throttle at any time.
EC000060
cCAfter 1,000 km of operation, the
transmission oil must be changed.
1,000 km and beyond
The vehicle can now be operated
normally.
EC000053
cC8Keep the engine speed out of
the tachometer red zone.
8If any engine trouble should
occur during the engine break-
in period, immediately have a
Yamaha dealer check the vehi-
cle.
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5-5
OPERATION AND IMPORTANT RIDING POINTS
5
EAU00458
ParkingWhen parking, stop the engine,
remove the key from the main switch,
and then turn the fuel cock lever to
“OFF”.
EW000058
w8Since 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.
EC000062
cCNever park in an area where there
are fire hazards such as grass or
other flammable materials.
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6-4
PERIODIC MAINTENANCE AND MINOR REPAIR
6
EAU03884
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 cylinders and calipers, 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*Autolube pump•Check operation.
•Bleed if necessary.√√√√
23 Transmission oil•Check oil level.√√√√√ √
•Change.√√
24*Cooling system•Check coolant level and vehicle for coolant leakage.√√√√ √
•Change.Every 3 years
25*Front and rear brake
switches•Check operation.√√√√√ √
26 Moving parts and cables•Lubricate.√√√√ √
27*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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6-9
PERIODIC MAINTENANCE AND MINOR REPAIR
6
EAU01833
Checking the spark plugThe 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
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. 2. Remove the spark plug as
shown, with the spark plug
wrench included in the owner’s
tool kit.
1
1. Spark plug wrench
Specified spark plug:
BR9ES (NGK)
BR8ES (NGK) (CH, A only)
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