SAFETY INFORMATION.....................1-1
DESCRIPTION.....................................2-1
Left view ...........................................2-1
Right view .........................................2-2
Controls and instruments .................2-3
INSTRUMENTS AND CONTROL
FUNCTIONS........................................3-1
Main switch/steering lock .................3-1
Indicator and warning lights .............3-2
Speedometer unit .............................3-3
Handlebar switches ..........................3-3
Clutch lever .......................................3-4
Shift pedal.........................................3-4
Brake lever ........................................3-5
Brake pedal.......................................3-5
Fuel tank cap ....................................3-5
Catalytic converter............................3-6
2-stroke engine oil ............................3-7
Fuel cock ..........................................3-7
Starter (choke) lever..........................3-8
Seat...................................................3-8
Shock absorber ................................3-9
YEIS handling precautions ...............3-9
YPVS .................................................3-9
Sidestand ........................................3-10
Ignition circuit cut-off system .........3-10
PRE-OPERATION CHECKS...............4-1
Pre-operation check list....................4-2OPERATION AND IMPORTANT RIDING
POINTS................................................5-1
Starting a cold engine ......................5-1
Starting a warm engine ....................5-2
Shifting ..............................................5-2
Engine break-in.................................5-2
Parking ..............................................5-3
PERIODIC MAINTENANCE AND
MINOR REPAIR...................................6-1
Owner’s tool kit .................................6-1
Periodic maintenance and
lubrication chart ............................6-2
Removing and installing cowlings
and panels .....................................6-5
Checking the spark plug ..................6-6
Transmission oil ................................6-7
Coolant .............................................6-8
Cleaning the air filter element
and check hose ...........................6-10
Ajusting the carburetor ...................6-11
Adjusting the engine idling
speed...........................................6-12
Ajusting the throttle cable free
play ..............................................6-12
Tires ................................................6-13
Spoke wheels .................................6-15
Adjusting the clutch lever free
play ..............................................6-15
Adjusting the brake lever free
play ..............................................6-16Adjusting the brake pedal position
and free play................................6-17
Adjusting the rear brake light
switch ..........................................6-17
Checking the front and rear
brake pads ..................................6-18
Changing the brake fluid ................6-19
Checking the drive chain slack ......6-19
Adjusting the drive chain slack.......6-20
Lubricating the drive chain .............6-20
Checking and lubricating the
cables ..........................................6-21
Checking and lubricating the
throttle grip and cable .................6-21
Adjusting the autolube pump .........6-21
Checking and lubricating the
brake and shift pedals.................6-21
Checking and lubricating the
breake and clutch levers .............6-21
Checking and lubricating the
sidestand .....................................6-21
Checking the front fork ...................6-22
Checking the steering.....................6-22
Checking the wheel bearings .........6-23
Replacing the fuse ..........................6-24
Replacing the headlight bulb..........6-24
Replacing the tail/brake light
bulb .............................................6-25
Replacing the turn signal light
bulb .............................................6-26
Supporting the motorcycle .............6-26
TABLE OF CONTENTS
1D0-F8199-E2.qxd 20/9/04 11:32 Página 4
EAU10410
Left view
DESCRIPTION
2-1
2
17
28
5
63 4
9
1. Headlight (page 6-24)
2. Radiator cover (page 6-5)
3. Fuel cock (page 3-7)
4. Air filter (page 6-10)
5. Choke lever (page 3-8)
6. Shift pedal (page 3-4)
7. Y.E.I.S (page 3-9)
8. Y.P.V.S. (page 3-9)
9. Oil tank (page 3-7)
1D0-F8199-E2.qxd 20/9/04 11:32 Página 12
ECA10700
CAUTION
The following precautions must be
observed to prevent a fire hazard or
other damages.
Use only unleaded gasoline.
The use of leaded gasoline will
cause unrepairable damage to
the catalytic converter.
Never park the vehicle near
possible fire hazards such as
grass or other materials that
easily burn.
Do not allow the engine to idle
too long.
EAU13460
2-stroke engine oil
1. Oil tank cap
2. Sensor
Make sure that there is sufficient oil in
the 2-stroke engine oil tank. Add the
recommended 2-stroke engine oil if
necessary.
NOTE:
Make sure that the 2-stroke engine oil
tank cap is properly installed.
Recommended oil:
Yamalube 2 or equivalent 2-stroke
engine oil (JASO grade “FC”, or ISO
grades “EG-C” or “EG-D”)
Oil quantity:
1,3 L (1,37 US qt) (0,29 Imp.qt)
EAU13560
Fuel cock
The fuel cock supplies fuel from the
tank to the carburetor while filtering it
also.
The fuel cock has three positions:OFF
1. Arrow mark
With the lever in this position, fuel will
not flow. Always return the lever to
this position when the engine is not
running.
ON
With the lever in this position, fuel
flows to the carburetor. Normal riding
is done with the lever in this position.
3
INSTRUMENT AND CONTROL FUNCTIONS
3-7
1
211
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EAU17710
Periodic maintenance and lubrication chart
NOTE:
The annual checks must be performed every year, except if a kilometer-based maintenance is performed
instead.
From 30000 km, repeat the maintenance intervals starting from 6000 km.
Items marked with an asterisk should be performed by a Yamaha dealer as they require special tools, data and
technical skills.
PERIODIC MAINTENANCE AND MINOR REPAIR
6-2
6
ODOMETER READING (x 1000 Km) ANNUAL
CHECK
NoITEM CHECK OR MAINTENANCE JOB 1 6 12 18 24
1*Fuel line• Check fuel hoses for cracks or damage.√√√√ √
2Spark plug• Replace.√√√√ √
3Air filter element• Clean.√√• Replace.√√
4Clutch• Check operation.
• Adjust.√√ √ √√
5*Front brake• Check operation, fluid level and vehicle for fluid leakage.√√ √ √√ √• Replace brake pads. Whenever worn to the limit
6*Rear brake• Check operation, fluid level and vehicle for fluid leakage.√√ √ √√ √• Replace brake pads. Whenever worn to the limit
7*Brake hoses• Check for cracks or damage.√√√√ √• Replace. Every 4 years
8*Wheels• Check runout, spoke tightness and for damage.
• Tighten spokes if necessary.√√√√
1D0-F8199-E2.qxd 20/9/04 11:32 Página 33
ODOMETER READING (x 1000 Km) ANNUAL
CHECK
NoITEM CHECK OR MAINTENANCE JOB 1 6 12 18 24
22Transmission oil• Check oil level.√√ √ √√ √• Change.√√
23 *Cooling system• Check coolant level and vehicle for coolant leakage.√√√√ √• Change. Every 3 years
24 *Front and rear
• Check operation.√√ √ √√ √
brake switches
25Moving parts and cables• Lubricate.√√√√ √
Throttle grip • Check operation and free play.
26 * •Adjust the throttle cable free play if necessary.√√√√ √
housing and cable
• Lubricate the throttle grip housing and cable.
27 *Muffler and exhaust pipe• Check the screw clamp for looseness.√√ √ √√
28 *Lights, signals • Check operation.
and switches• Adjust headlight beam.√√ √ √√ √
PERIODIC MAINTENANCE AND MINOR REPAIR
6-4
6
EAU18670
NOTE:
The air filter needs more frequent service if you are riding in unusually wet or dusty areas.
Hydraulic brake service
• Regularly check and, if necessary, correct the brake fluid level.
• Every two years replace the internal components of the brake master cylinders and calipers, and change the bra-
ke fluid.
• Replace the brake hoses every four years and if cracked or damaged.
1D0-F8199-E2.qxd 20/9/04 11:32 Página 35
Tightening torque:
Coolant drain bolt:
10 Nm (1,0 m•kgf)
8. Connect the coolant reservoir
hose.
9. Pour the recommended coolant
into the radiator until it is full.
Recommended antifreeze:
High quality ethylene glycol antifree-
ze containing corrosion inhibitors for
aluminum engines
Antifreeze/water mixing ratio:
1:1
Coolant quantity:
Radiator capacity (including all rou-
tes):
0,92 L (0,97 US qt)
Coolant reservoir capacity:
0,3 L (0,32 US qt)
ECA10470
CAUTION
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 coo-
lant as soon as possible, other-
wise the engine may not be
sufficiently cooled and the coo-
ling system will not be protec-
ted against frost and corrosion.
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 effective-
ness of the coolant will be
reduced.
10. Install the radiator cap.
11. Run the engine several minutes.
Stop the engine and recheck the
coolant level in the radiator. If it is
low, add more coolant until it rea-
ches the top of the radiator.
12. Install the radiator cap stopper
bolt.
13. Fill the coolant reservoir with
coolant up to maximum level.
14. Install the coolant reservoir cap
and check for coolant leakage.
NOTE:
If any leakage is found, ask a Yamaha
dealer to inspect the cooling system.
15. Install the cowling and the panel.
EAU20831
Cleaning the air filter
element and check hose
The air filter element should be clea-
ned at the intervals specified in the
periodic maintenance and lubrication
chart. Clean the air filter element more
frequently if you are riding in unu-
sually wet or dusty areas. In addition,
the air filter check hose must be fre-
quently checked and cleaned if
necessary.
1. Screws (x3)
6
PERIODIC MAINTENANCE AND MINOR REPAIR
6-10
1
1D0-F8199-E2.qxd 20/9/04 11:32 Página 41
To clean the air filter element
1. Remove panel E. (See page 6-6.)
2. Remove the air filter case cover
by removing the screws.
3. Pull the air filter element out.
1. Guide
2. Filter
4. Remove the sponge material
from the air filter element frame,
clean it with solvent, and then
squeeze the remaining solvent
out.5. Apply oil of the recommended
type to the entire surface of the
sponge material, and then sque-
eze the excess oil out.
NOTE:
The sponge material should be wet
but not dripping.
Recommended oil:
Foam air filter oil
6. Pull the sponge material over the
air filter element frame.
7. Insert the element into the air fil-
ter case.
ECA10480
CAUTION
Make sure that the air filter ele-
ment is properly seated in the
air filter case.
The engine should never be
operated without the air filter
element installed, otherwise
the piston(s) and/or cylinder(s)
may become excessively worn.
8. Install the air filter case cover by
installing the screws.
9. Install the panel.To clean the air filter check hose
1. Check the hose at the bottom of
the air filter case for accumulated
dirt or water.
2. If dirt or water is visible, remove
the hose, clean it, and then install
it.
EAU21280
Adjusting the carburetor
The carburetor is an important part of
the engine and requires very sophisti-
cated adjustment. Therefore, most
carburetor adjustments should be left
to a Yamaha dealer, who has the
necessary professional knowledge
and experience. The adjustment des-
cribed in the following section, howe-
ver, may be serviced by the owner as
part of routine maintenance.
ECA10550
CAUTION
The carburetor has been set and
extensively tested at the Yamaha
factory. Changing these settings
without sufficient technical know-
ledge may result in poor perfor-
mance of or damage to the engine.
6
PERIODIC MAINTENANCE AND MINOR REPAIR
6-11
12
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DimensionsOverall length
DT125RE 2210 mm
DT125X 2139 mm
Overall width
795 mm
Overall height
DT125RE 1200 mm
DT125X 1121 mm
Seat height
DT125RE 900 mm
DT125X 886 mm
Wheelbase
DT125RE 1415 mm
DT125X 1396 mm
Ground clearance
DT125RE 300 mm
DT125X 271 mm
Minimum turning radius
DT125RE 2100 mm
DT125X 2016 mm
WeightWith oil and fuel
DT125RE 126.0 kg
DT125X 134.0 kg
EngineEngine type
Liquid cooled 2-stroke
Cylinder arrangement
Forward-inclined single cylinder
Displacement
124.0 cm
3
Bore x stroke
56.0 x 50.7 mmCompression ratio
6.70 :1
Starting system
Electric starter
Lubrication system
Separate lubrication (Yamaha autolube)
Type
YAMALUBE 2-cycle oil or 2-stroke engine
oil (JASO FC g
Engine oil quantityQuantity
1.3 L
Transmission oilType
SAE10W30 type SE motor oil
Oil change quantity
0.75 L
Cooling systemCoolant reservoir capacity (up to the maxi-
mum leve
0.30 L
Radiator capacity (including all routes)
0.92 L
Air filterAir filter element
Wet element
FuelRecommended fuel
Regular unleaded gasoline only
Fuel tank capacity
10.7 L
Fuel reserve amount
1.8 L
CarburetorManufacturer
MIKUNI
Type x quantity
TM28-92 x1
Spark plug(s)Manufacturer/model
NGK/BR8ES
Spark plug gap
0.7-0.8 mm
Clutch type
Wet, multiple-disc
TransmissionPrimary reduction system
Helical gear
Primary reduction ratio
71/22 (3.227)
Secondary reduction system
Chain drive
Secondary reduction ratio
57/16 (3.563)
Transmission type
Constant mesh 6-speed
Operation
Left foot operation
Gear ratio1st
34/12 (2.833)
2nd
30/16 (1.875)
3rd
24/17 (1.412)
4th
24/21 (1.143)
8
SPECIFICATIONS
8-1
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