2006 YAMAHA DT125R engine

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.
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EAU21340
Adjusting the engine idling
speed
1. Idle adjusting bolt
The engine idling speed must be
checked and, if necessary, adjusted
as follows at the intervals specified in
the periodic maintenance and lubrica-
tion chart.
The engine should be warm before
making this adjustment.
NOTE:
The engine is warm when it
quickly responds to the throttle.
A diagnostic tachometer is nee-
ded to make this adjustment.
1. Attach the tachometer to the
spark plug lead.2. Check the engine idling speed
and, if necessary, adjust it to spe-
cification by turning the throttle
stop screw. To increase the engi-
ne idling speed, turn the screw in
direction (a). To decrease the
engine idling speed, turn the
screw in direction (b).
Engine idling speed:
1250-1450 r/min
NOTE:
If the specified idling speed cannot be
obtained as described above, have a
Yamaha dealer make the adjustment.
EAU21370
Adjusting the throttle cable
free play
(a) Free play
The throttle cable free play should
measure 3-5 mm (0,11-0,19 in) at the
throttle grip. Periodically check the
throttle cable free play and, if neces-
sary, adjust it as follows.
NOTE:
The engine idling speed must be
correctly adjusted before checking
and adjusting the throttle cable free
play.
1. Lock nut
2. Adjusting nut
1. Loosen the locknut.
2. To increase the throttle cable free
play, turn the adjusting nut in
direction (a). To decrease the
throttle cable free play, turn the
adjusting nut in direction (b).
3. Tighten the locknut.
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EAU22960
To adjust the drive chain slack
1. Axle nut
2. Chain tensioner
1. Loosen the axle nut.
2. To tighten the drive chain, turn
the adjusting plate on each side
of the swingarm in direction (a).
To loosen the drive chain, turn
the adjusting plate on each side
of the swingarm in direction (b),
and then push the rear wheel for-
ward.
NOTE:
Make sure that both adjusting plates
are in the same position for proper
wheel alignment.
ECA10570
CAUTION
Improper drive chain slack will
overload the engine as well as
other vital parts of the motorcycle
and can lead to chain slippage or
breakage. To prevent this from
occurring, keep the drive chain
slack within the specified limits.
3. Tighten the axle nut to the speci-
fied torque.
Tightening torque:
Axle nut:
90 Nm (9,0 m•kgf)
EAU23021
Lubricating the drive chain
The drive chain must be cleaned and
lubricated at the intervals specified in
the periodic maintenance and lubrica-
tion chart, otherwise it will quickly
wear out, especially when riding in
dusty or wet areas. Service the drive
chain as follows.
ECA10581
CAUTION
The drive chain must be lubricated
after washing the motorcycle and
riding in the rain.
1. Clean the drive chain with kero-
sene and a small soft brush.
ECA11120
CAUTION
To prevent damaging the O-rings,
do not clean the drive chain with
steam cleaners, high-pressure
washers or inappropriate solvents.
2. Wipe the drive chain dry.
3. Thoroughly lubricate the drive
chain with a special O-ring chain
lubricant.
ECA11110
CAUTION
Do not use engine oil or any other
lubricants for the drive chain, as
they may contain substances that
could damage the O-rings.
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EAU23100
Checking and lubricating the
cables
The operation of all control cables
and the condition of the cables
should be checked before each ride,
and the cables and cable ends should
be lubricated if necessary. If a cable is
damaged or does not move smoothly,
have a Yamaha dealer check or repla-
ce it.
Recommended lubricant:
Engine oil
EWA10720
s s
WARNING
Damage to the outer sheath may
interfere with proper cable opera-
tion and will cause the inner cable
to rust. Replace a damaged cable
as soon as possible to prevent
unsafe conditions.
EAU23110
Checking and lubricating the
throttle grip and cable
The operation of the throttle grip
should be checked before each ride.
In addition, the cable should be lubri-
cated or replaced at the intervals spe-
cified in the periodic maintenance
chart.
EAU23120
Adjusting the Autolube pump
The Autolube pump is a vital and sop-
histicated component of the engine,
which must be adjusted by a Yamaha
dealer at the intervals specified in the
periodic maintenance and lubrication
chart.
EAU23131
Checking and lubricating the
brake and shift pedals
The operation of the brake and shift
pedals should be checked before
each ride, and the pedal pivots
should be lubricated if necessary.
Recommended lubricant:
Lithium-soap-based grease (all-pur-
pose grease)
EAU23140
Checking and lubricating the
brake and clutch levers
The operation of the brake and clutch
levers should be checked before each
ride, and the lever pivots should be
lubricated if necessary.
Recommended lubricant:
Lithium-soap-based grease (all-pur-
pose grease)
EAU23200
Checking and lubricating the
sidestand
The operation of the sidestand should
be checked before each ride, and the
sidestand pivot and metal-to-metal
contact surfaces should be lubricated
if necessary.
EWA10730
s s
WARNING
If the sidestand does not move up
and down smoothly, have a Yama-
ha dealer check or repair it.
6
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Recommended lubricant:
Lithium-soap-based grease (all-pur-
pose grease)
EAU23271
Checking the front fork
The condition and operation of the
front fork must be checked as follows
at the intervals specified in the perio-
dic maintenance and lubrication
chart.
To check the condition
EWA10750
s s
WARNING
Securely support the motorcycle so
that there is no danger of it falling
over.
Check the inner tubes for scratches,
damage and excessive oil leakage.To check the operation
1. Place the motorcycle on a level
surface and hold it in an upright
position.
2. While applying the front brake,
push down hard on the handle-
bars several times to check if the
front fork compresses and
rebounds smoothly.ECA10590
CAUTION
If any damage is found or the front
fork does not operate smoothly,
have a Yamaha dealer check or
repair it.
EAU23280
Checking the steering
Worn or loose steering bearings may
cause danger. Therefore, the opera-
tion of the steering must be checked
as follows at the intervals specified in
the periodic maintenance and lubrica-
tion chart.
1. Place a stand under the engine to
raise the front wheel off the
ground.
EWA10750
s s
WARNING
Securely support the motorcycle so
that there is no danger of it falling
over.
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ECA10680
CAUTION
Do not overtighten the screws,
otherwise the lens may break.
EAU24201
Replacing a turn signal light
bulb
1. Screw
2. Lens
3. Bulb
1. Remove the turn signal light lens
by removing the screw.
2. Remove the defective bulb by
pushing it in and turning it coun-
terclockwise.
3. Insert a new bulb into the socket,
push it in, and then turn it clock-
wise until it stops.4. Install the lens by installing the
screw.
ECA11190
CAUTION
Do not overtighten the screw,
otherwise the lens may break.
EAU24350
Supporting the motorcycle
Since this model is not equipped with
a centerstand, follow these precau-
tions when removing the front and
rear wheel or performing other main-
tenance requiring the motorcycle to
stand upright. Check that the
motorcycle is in a stable and level
position before starting any mainte-
nance. A strong wooden box can be
placed under the engine for added
stability.
To service the front wheel
1. Stabilize the rear of the motorcy-
cle by using a motorcycle stand
or, if an additional motorcycle
stand is not available, by placing
a jack under the frame in front of
the rear wheel.2. Raise the front wheel off the
ground by using a motorcycle
stand.
To service the rear wheel
Raise the rear wheel off the ground by
using a motorcycle stand or, if a
motorcycle stand is not available, by
placing a jack either under each side
of the frame in front of the rear wheel
or under each side of the swingarm.
EAU24360
Front wheel
EAU24640
To remove the front wheel
1. Speedometer cable
2. Axle retainer nut (x4)
3. Wheel axle
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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
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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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