engine YAMAHA DT125R 2005 Owner's Guide

EAU25921
Troubleshooting charts
Starting problems or poor engine performanceEWA10840
s s
WARNING
Keep away open flames and do not smoke while checking or working on the fuel system.
PERIODIC MAINTENANCE AND MINOR REPAIR
6-30
6
Check the fuel level in
the fuel tank.
1. FuelThere is enough fuel.
There is no fuel.Check the compression.
Supply fuel.
The engine does not start.
Check the compression.
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 plug
and check the electrodes.
3. IgnitionWipe off with a dry cloth and correct the
spark plug gap, or replace the spark plug.
Have a Yamaha dealer check the vehicle.
The engine does not start.
Have a Yamaha dealer
check the vehicle.
The engine does not start.
Check the battery.
Operate the electric starter.
4. BatteryThe engine turns over
quickly.
The engine turns over
slowly.The battery is good.
Check the battery lead connections,
and charge the battery if necessary.
Dry
WetOpen the throttle halfway and operate
the electric starter.
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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.
PERIODIC MAINTENANCE AND MINOR REPAIR
6-31
6Wait 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.
Engine overheatingEWA10400
s s
WARNING
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 his-
sing sound has stopped, press down on the cap while turning it counterclockwise, and then remove the cap.
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EAU26000
Care
While the open design of a motorcy-
cle reveals the attractiveness of the
technology, it also makes it more vul-
nerable. Rust and corrosion can
develop even if high-quality compo-
nents are used. A rusty exhaust pipe
may go unnoticed on a car, however,
it detracts from the overall appearan-
ce of a motorcycle. Frequent and pro-
per care does not only comply with
the terms of the warranty, but it will
also keep your motorcycle looking
good, extend its life and optimize its
performance.
Before cleaning
1. Cover the muffler outlet with a
plastic bag after the engine has
cooled down.
2. Make sure that all caps and
covers as well as all electrical
couplers and connectors, inclu-
ding the spark plug cap, are
tightly installed.3. Remove extremely stubborn dirt,
like oil burnt onto the crankcase,
with a degreasing agent and a
brush, but never apply such pro-
ducts onto seals, gaskets, sproc-
kets, the drive chain and wheel
axles. Always rinse the dirt and
degreaser off with water.
Cleaning
ECA10770
CAUTION
Avoid using strong acidic whe-
el cleaners, especially on spo-
ked wheels. If such products
are used on hard-to-remove
dirt, do not leave the cleaner on
the affected area any longer
than instructed. Also, tho-
roughly rinse the area off with
water, immediately dry it, and
then apply a corrosion protec-
tion spray.
Improper cleaning can damage
windshields, cowlings, panels
and other plastic parts. Use
only a soft, clean cloth or spon-
ge with mild detergent and
water to clean plastic.
Do not use any harsh chemical
products on plastic parts. Be
sure to avoid using cloths or
sponges which have been in
contact with strong or abrasive
cleaning products, solvent or
thinner, fuel (gasoline), rust
removers or inhibitors, brake
fluid, antifreeze or electrolyte.
Do not use high-pressure was-
hers or steam-jet cleaners sin-
ce they cause water seepage
and deterioration in the follo-
wing areas: seals (of wheel and
swingarm bearings, fork and
brakes), electric components
(couplers, connectors, instru-
ments, switches and lights),
breather hoses and vents.
For motorcycles equipped with
a windshield: Do not use strong
cleaners or hard sponges as
they will cause dulling or scrat-
ching. Some cleaning com-
pounds for plastic may leave
scratches on the windshield.
Test the product on a small hid-
den part of the windshield to
make sure that it does not lea-
7
MOTORCYCLE CARE AND STORAGE
7-1
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ve any marks. If the windshield
is scratched, use a quality
plastic polishing compound
after washing.
After normal use
Remove dirt with warm water, a mild
detergent, and a soft, clean sponge,
and then rinse thoroughly with clean
water. Use a toothbrush or bottle-
brush for hard-to-reach areas. Stub-
born dirt and insects will come off
more easily if the area is covered with
a wet cloth for a few minutes before
cleaning.
After riding in the rain, near the sea or
on salt-sprayed roads
Since sea salt or salt sprayed on
roads during winter are extremely
corrosive in combination with water,
carry out the following steps after
each ride in the rain, near the sea or
on salt-sprayed roads.
NOTE:
Salt sprayed on roads in the winter
may remain well into spring.
1. Clean the motorcycle with cold
water and a mild detergent, after
the engine has cooled down.
ECA10790
CAUTION
Do not use warm water since it
increases the corrosive action of
the salt.
2. Apply a corrosion protection
spray on all metal, including
chrome- and nickel-plated, surfa-
ces to prevent corrosion.
After cleaning
1. Dry the motorcycle with a cha-
mois or an absorbing cloth.
2. Immediately dry the drive chain
and lubricate it to prevent it from
rusting.
3. Use a chrome polish to shine
chrome, aluminum and stainless-
steel parts, including the exhaust
system. (Even the thermally indu-
ced discoloring of stainless-steel
exhaust systems can be removed
through polishing.)4. To prevent corrosion, it is recom-
mended to apply a corrosion pro-
tection spray on all metal, inclu-
ding chrome- and nickel-plated,
surfaces.
5. Use spray oil as a universal clea-
ner to remove any remaining dirt.
6. Touch up minor paint damage
caused by stones, etc.
7. Wax all painted surfaces.
8. Let the motorcycle dry comple-
tely before storing or covering it.
EWA10930
s s
WARNING
Make sure that there is no oil or
wax on the brakes or tires. If
necessary, clean the brake
discs and brake linings with a
regular brake disc cleaner or
acetone, and wash the tires
with warm water and a mild
detergent.
Before operating the motorcy-
cle test its braking performan-
ce and cornering behavior.
7
MOTORCYCLE CARE AND STORAGE
7-2
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ECA10800
CAUTION
Apply spray oil and wax spa-
ringly and make sure to wipe
off any excess.
Never apply oil or wax to any
rubber and plastic parts, but
treat them with a suitable care
product.
Avoid using abrasive polishing
compounds as they will wear
away the paint.
NOTE:
Consult a Yamaha dealer for advice
on what products to use.
EAU26150
Storage
Short-term
Always store your motorcycle in a
cool, dry place and, if necessary, pro-
tect it against dust with a porous
cover.
ECA10810
CAUTION
Storing the motorcycle in a
poorly ventilated room or cove-
ring it with a tarp, while it is still
wet, will allow water and humi-
dity to seep in and cause rust.
To prevent corrosion, avoid
damp cellars, stables (because
of the presence of ammonia)
and areas where strong chemi-
cals are stored.
Long-term
Before storing your motorcycle for
several months:
1. Follow all the instructions in the
“Care” section of this chapter.
2. For motorcycles equipped with a
fuel cock that has an “OFF” posi-
tion: Turn the fuel cock lever to
“OFF”.
3. Drain the carburetor float cham-
ber by loosening the drain bolt;
this will prevent fuel deposits
from building up. Pour the drai-
ned fuel into the fuel tank.4. Fill up the fuel tank and add fuel
stabilizer (if available) to prevent
the fuel tank from rusting and the
fuel from deteriorating.
5. Perform the following steps to
protect the cylinder, piston rings,
etc. from corrosion.
a. Remove the spark plug cap and
spark plug.
b. Pour a teaspoonful of engine oil
into the spark plug bore.
c. Install the spark plug cap onto
the spark plug, and then place
the spark plug on the cylinder
head so that the electrodes are
grounded. (This will limit sparking
during the next step.)
d. Turn the engine over several
times with the starter. (This will
coat the cylinder wall with oil.)
e. Remove the spark plug cap from
the spark plug, and then install
the spark plug and the spark plug
cap.
7
MOTORCYCLE CARE AND STORAGE
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EWA10950
s s
WARNING
To prevent damage or injury from
sparking, make sure to ground the
spark plug electrodes while turning
the engine over.
6. Lubricate all control cables and
the pivoting points of all levers
and pedals as well as of the
sidestand/centerstand.
7. Check and, if necessary, correct
the tire air pressure, and then lift
the motorcycle so that both of its
wheels are off the ground. Alter-
natively, turn the wheels a little
every month in order to prevent
the tires from becoming degra-
ded in one spot.
8. Cover the muffler outlet with a
plastic bag to prevent moisture
from entering it.9. Remove the battery and fully
charge it. Store it in a cool, dry
place and charge it once a
month. Do not store the battery in
an excessively cold or warm pla-
ce [less than 0 °C (30 °F) or more
than 30 °C (90 °F)]. For more
information on storing the bat-
tery, see page 6-23.
NOTE:
Make any necessary repairs before
storing the motorcycle.
7
MOTORCYCLE CARE AND STORAGE
7-4
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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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EAU26440
Engine serial number
1. Engine serial number
The engine serial number is stamped
into the crankcase.
EAU26480
Model label
1. Model label
The model label is affixed to the frame
under the seat. (See page 3-8.)
Record the information on this label in
the space provided. This information
will be needed when ordering spare
parts from a Yamaha dealer.
9
CONSUMER INFORMATION
9-2
11
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AAdjusting the autolube pump ..................6-21
Adjusting the brake lever free play ..........6-16
Adjusting the brake pedal position and
free play .................................................6-17
Adjusting the clutch lever free play .........6-15
Adjusting the drive chain slack ................6-20
Adjusting the engine idling speed ...........6-12
Adjusting the rear brake light switch .......6-17
Ajusting the carburetor ............................6-11
Ajusting the throttle cable free play .........6-12
BBrake lever .................................................3-5
Brake pedal ................................................3-5
CCare............................................................7-1
Catalytic converter .....................................3-6
Changing the brake fluid..........................6-19
Checking and lubricating the brake and
shift pedals ............................................6-21
Checking and lubricating the breake and
clutch levers...........................................6-21
Checking and lubricating the cables .......6-21
Checking and lubricating the sidestand ..6-21
Checking and lubricating the throttle grip
and cable ...............................................6-21
Checking the drive chain slack ................6-19
Checking the front and rear brake
pads .......................................................6-18
Checking the front fork ............................6-22
Checking the spark plug ............................6-6
Checking the steering ..............................6-22
Checking the wheel bearings ..................6-23Cleaning the air filter element and check
hose .......................................................6-10
Clutch lever ................................................3-4
Controls and instruments ..........................2-3
Coolant.......................................................6-8
D2-stroke engine oil .....................................3-7
EEngine break-in ..........................................5-2
FFront wheel ..............................................6-26
Fuel cock....................................................3-7
Fuel tank cap .............................................3-5
H
Handlebar switches ...................................3-3
IIdentification numbers ...............................9-1
Ignition circuit cut-off system ..................3-10
Indicator and warning lights ......................3-2
LLeft view .....................................................2-1
Lubricating the drive chain ......................6-20
MMain switch/steering lock ..........................3-1
OOwner’s tool kit ..........................................6-1
PParking .......................................................5-3
Periodic maintenance and lubrication
chart .........................................................6-2
Pre-operation check list .............................4-2
RRear wheel ...............................................6-28Removing and installing cowlings and
panels ......................................................6-5
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
Right view ..................................................2-2
SSeat ............................................................3-8
Shift pedal ..................................................3-4
Shifting .......................................................5-2
Shock absorber..........................................3-9
Sidestand .................................................3-10
Specifications.............................................8-1
Speedometer unit ......................................3-3
Spoke wheels...........................................6-15
Starter (choke) lever ...................................3-8
Starting a cold engine ................................5-1
Starting a warm engine ..............................5-2
Storage.......................................................7-3
Supporting the motorcycle ......................6-26
TTires .........................................................6-13
Transmission oil .........................................6-7
Troubleshooting .......................................6-29
YYEIS handling precautions.........................3-9
YPVS ..........................................................3-9
INDEX
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