YAMAHA YBR125 2004 Workshop Manual

5. Remove the air filter elements from the guide and clean
them with solvent. After cleaning, remove the remaining
solvent by squeezing the air filter.
6. Apply recommended oil to the entire surface of the filter
and squeeze out the excess oil. The air filter should be
wet but not dripping.
Recommended oil:
Engine oil 20W50
7. Reinstall the air filter and lock it with the clamp.
8. Install the air filter case cover and the right side cover.
Make sure the element is properly seated in the air filter
case.
The engine should never be run without the air filter
element installed; excessive piston and/or cylinder wear
may result.
6-11
CAUTION:
CAUTION:
5. Remove the air filter elements from the guide and clean
them with solvent. After cleaning, remove the remaining
solvent by squeezing the air filter.
6. Apply recommended oil to the entire surface of the filter
and squeeze out the excess oil. The air filter should be
wet but not dripping.
Recommended oil:
Engine oil 20W50
7. Reinstall the air filter and lock it with the clamp.
8. Install the air filter case cover and the right side cover.
Make sure the element is properly seated in the air filter
case.
The engine should never be run without the air filter
element installed; excessive piston and/or cylinder wear
may result.
6-11
CAUTION:
CAUTION:

Valve clearance adjustment
The correct valve clearance changes with use, resulting in
improper fuel/air supply or engine noise. To prevent this,
valve clearance must be adjusted regularly. This adjustment,
however, should be left to a professional Yamaha service
technician. Carburetor adjustment
The carburetor is a vital part of the engine. Adjusting should
be left to a Yamaha dealer who has the professional
knowledge, specialized data, and equipment to do so
properly. However, the following may be serviced by the
owner as part of routine maintenance.
The carburetor was set at Yamaha factory after many
tests. If the settings are changed, poor engine
performance and damage may result.
6-12
CAUTION:
Valve clearance adjustment
The correct valve clearance changes with use, resulting in
improper fuel/air supply or engine noise. To prevent this,
valve clearance must be adjusted regularly. This adjustment,
however, should be left to a professional Yamaha service
technician. Carburetor adjustment
The carburetor is a vital part of the engine. Adjusting should
be left to a Yamaha dealer who has the professional
knowledge, specialized data, and equipment to do so
properly. However, the following may be serviced by the
owner as part of routine maintenance.
The carburetor was set at Yamaha factory after many
tests. If the settings are changed, poor engine
performance and damage may result.
6-12
CAUTION:

NOTE:
A diagnostic tachometer must be used for this procedure.
1. Attach the tachometer. Start the engine and warm it up
for a few minutes (normally, 1 or 2 minutes) at
approximately 1,000 to 2,000 r/min. Occasionally rev
the engine to 4,000 to 5,000 r/min. The engine is warm
when it quickly responds to the throttle.
2. Set the idle to the specified engine speed by adjusting
the throttle stop screw; turn the screw in to increase
engine speed and out to decrease engine speed.
NOTE:
If the specified idle speed cannot be obtained by performing
the above adjustment, consult a Yamaha dealer.
6-13
Standard idle speed:
1,300 ~ 1,400 r/min
1. Throttle stop screw
Idle speed adjustment
NOTE:
A diagnostic tachometer must be used for this procedure.
1. Attach the tachometer. Start the engine and warm it up
for a few minutes (normally, 1 or 2 minutes) at
approximately 1,000 to 2,000 r/min. Occasionally rev
the engine to 4,000 to 5,000 r/min. The engine is warm
when it quickly responds to the throttle.
2. Set the idle to the specified engine speed by adjusting
the throttle stop screw; turn the screw in to increase
engine speed and out to decrease engine speed.
NOTE:
If the specified idle speed cannot be obtained by performing
the above adjustment, consult a Yamaha dealer.
6-13
Standard idle speed:
1,300 ~ 1,400 r/min
1. Throttle stop screw
Idle speed adjustment

NOTE:
Before checking the throttle cable free play, the engine
idling speed should be adjusted.
The throttle cable should have an specified free play in the
turning direction at the grip flange. If the free play is incorrect,
follow the instructions below.
1. Loosen the locknut.
2. Turning the adjuster to:
Direction A : increase free play
Direction B: reduces free play
3. Tighten the locknut.
6-14
Free play:
3 ~ 7 mm (0.12 ~ 0.28 in) Throttle cable adjustment
1. Free play
2. Locknut
3. Adjuster
NOTE:
Before checking the throttle cable free play, the engine
idling speed should be adjusted.
The throttle cable should have an specified free play in the
turning direction at the grip flange. If the free play is incorrect,
follow the instructions below.
1. Loosen the locknut.
2. Turning the adjuster to:
Direction A : increase free play
Direction B: reduces free play
3. Tighten the locknut.
6-14
Free play:
3 ~ 7 mm (0.12 ~ 0.28 in) Throttle cable adjustment
1. Free play
2. Locknut
3. Adjuster

6-15
1. Spark plug gap
Spark plug inspection
The spark plug is an important engine component and is
easy to inspect. The condition of the spark plug can indicate
the condition of the engine.
The ideal color on the white porcelain insulator around the
center electrode is a medium to light tan color for a
motorcycle that is being ridden normally. Do not attempt to
diagnose any problems yourself. Instead, take the
motorcycle to a Yamaha dealer. You should periodically
remove and inspect the spark plug because heat and
deposits will cause the spark plug to slowly break down
and erode.
If electrode erosion becomes excessive, or if carbon and
other deposits are excessive, you should replace the spark
plug with the specified plug.Standard spark plug:
CR7HSA (NGK) and U22FSR-U (DENSO)
Before installing the spark plug, measure the electrode gap
with a wire thickness gauge and adjust the gap to
specification as necessary.
Spark plug gap:
0.7 mm ( 0.028 in)
When installing the plug, always clean the gasket surface
and use a new gasket. Wipe off any grime from the threads,
and torque the spark plug properly.
Spark plug torque:
12.5 N.m (1.25 Kgf.m, 9 lbf.ft)
NOTE:
If a torque wrench is not available when you are installing a
spark plug, a good estimate of the correct torque is 1/4 to
1/2 turn past finger tight. Have the spark plug torqued to
the correct value as soon as possible with a torque wrench.
6-15
1. Spark plug gap
Spark plug inspection
The spark plug is an important engine component and is
easy to inspect. The condition of the spark plug can indicate
the condition of the engine.
The ideal color on the white porcelain insulator around the
center electrode is a medium to light tan color for a
motorcycle that is being ridden normally. Do not attempt to
diagnose any problems yourself. Instead, take the
motorcycle to a Yamaha dealer. You should periodically
remove and inspect the spark plug because heat and
deposits will cause the spark plug to slowly break down
and erode.
If electrode erosion becomes excessive, or if carbon and
other deposits are excessive, you should replace the spark
plug with the specified plug.Standard spark plug:
CR7HSA (NGK) and U22FSR-U (DENSO)
Before installing the spark plug, measure the electrode gap
with a wire thickness gauge and adjust the gap to
specification as necessary.
Spark plug gap:
0.7 mm ( 0.028 in)
When installing the plug, always clean the gasket surface
and use a new gasket. Wipe off any grime from the threads,
and torque the spark plug properly.
Spark plug torque:
12.5 N.m (1.25 Kgf.m, 9 lbf.ft)
NOTE:
If a torque wrench is not available when you are installing a
spark plug, a good estimate of the correct torque is 1/4 to
1/2 turn past finger tight. Have the spark plug torqued to
the correct value as soon as possible with a torque wrench.

6-16
Front brake adjustment
1. Adjuster 2. Locknut 3. Free play
The front brake lever free play should be adjusted to 10
~15 mm (0,4 ~0.6 in).
1. Loosen the locknut
2. Turn the adjusting nut in direction clockwise to increase
free play and direction counterclockwise to decrease
free play.
3. Tighten the locknut.
4. Major adjustment may be made at adjusting bolt wich
is located besides the front brake shoe plate.
5. To complete the adjustment, turn the adjusting bolt
clockwise until appropriate freeplay is obtained.
Cheking the brakes shoes
1. Wear limit line 2. Wear indicator
Apply the brake and inspect the wear indicator. If the
indicator reaches the wear limit line, ask a Yamaha delaer
to replace the shoes.
6-16
Front brake adjustment
1. Adjuster 2. Locknut 3. Free play
The front brake lever free play should be adjusted to 10
~15 mm (0,4 ~0.6 in).
1. Loosen the locknut
2. Turn the adjusting nut in direction clockwise to increase
free play and direction counterclockwise to decrease
free play.
3. Tighten the locknut.
4. Major adjustment may be made at adjusting bolt wich
is located besides the front brake shoe plate.
5. To complete the adjustment, turn the adjusting bolt
clockwise until appropriate freeplay is obtained.
Cheking the brakes shoes
1. Wear limit line 2. Wear indicator
Apply the brake and inspect the wear indicator. If the
indicator reaches the wear limit line, ask a Yamaha delaer
to replace the shoes.

6-17
Rear brake adjustment
a. Free play: 20 ~ 30 mm (0.8 ~ 1.2 in)
Check the free play the rear brake pedal free play should
be adjusted to 20 ~ 30 mm (0.8 ~ 1.2 in) at the brake pedal
end.
Turn the adjusting nut in direction a to increase free play
and in direction b to decrease free play.
Press the brake pedal several times and check if the wheel
turns free when the pedal is released.
For brake pedal adjustment, be sure to proceed as
follows (it is advisable to have a Yamaha dealer make
this adjustment.)
Check the operation of the brake light after adjusting
the rear brake.
1. Adjusting nut
CAUTION:
6-17
Rear brake adjustment
a. Free play: 20 ~ 30 mm (0.8 ~ 1.2 in)
Check the free play the rear brake pedal free play should
be adjusted to 20 ~ 30 mm (0.8 ~ 1.2 in) at the brake pedal
end.
Turn the adjusting nut in direction a to increase free play
and in direction b to decrease free play.
Press the brake pedal several times and check if the wheel
turns free when the pedal is released.
For brake pedal adjustment, be sure to proceed as
follows (it is advisable to have a Yamaha dealer make
this adjustment.)
Check the operation of the brake light after adjusting
the rear brake.
1. Adjusting nut
CAUTION:

6-18
Brake light switch adjustment
The rear brake light switch is activated by the brake pedal
and is properly adjusted when the brake light comes on just
before braking takes effect. To adjust the rear brake light
switch, hold the switchbody so it does not rotate while turning
the adjusting nut.
Turn the adjusting nut in direction a to make the brake
light come on earlier.
Turn the adjusting nut in direction b to make the brake
light come on later.
1. Brake light switch 2. Adjusting nut
Clutch adjustment
The clutch lever free play should be adjusted to 10~15 mm
(0.4 ~0.6 in) at the clutch lever end. If the free play is
incorrect, adjust as follows.
1. Loosen the lock nut at the handlebar.
2. Turn the adjuster in or out until proper lever free play is
obtained.
3. Tighten the lock nut.
4. If the free play is still incorrect, make an adjustment at
the crankcase side.
NOTE:
If proper adjustment cannot be obtained or the clutch does
not work correctly, ask a Yamaha dealer to inspect the
internal clutch mechanism.
1. Lock nut 2. Adjuster a. 10~15 mm (0.4 ~0.5 in)
6-18
Brake light switch adjustment
The rear brake light switch is activated by the brake pedal
and is properly adjusted when the brake light comes on just
before braking takes effect. To adjust the rear brake light
switch, hold the switchbody so it does not rotate while turning
the adjusting nut.
Turn the adjusting nut in direction a to make the brake
light come on earlier.
Turn the adjusting nut in direction b to make the brake
light come on later.
1. Brake light switch 2. Adjusting nut
Clutch adjustment
The clutch lever free play should be adjusted to 10~15 mm
(0.4 ~0.6 in) at the clutch lever end. If the free play is
incorrect, adjust as follows.
1. Loosen the lock nut at the handlebar.
2. Turn the adjuster in or out until proper lever free play is
obtained.
3. Tighten the lock nut.
4. If the free play is still incorrect, make an adjustment at
the crankcase side.
NOTE:
If proper adjustment cannot be obtained or the clutch does
not work correctly, ask a Yamaha dealer to inspect the
internal clutch mechanism.
1. Lock nut 2. Adjuster a. 10~15 mm (0.4 ~0.5 in)

6-19
Drive chain slack check NOTE:
Spin the wheel several times and find the tightest position
of the chain. Check and/or adjust the chain slack while it is
in this tightest position.
To check the chain slack the motorcycle must be held
straight up with both wheels on the ground and without rider.
Check the slack at the position shown in the illustration.
Normal slack is approximately 20 ~ 30 mm ( 0.8 ~ 1.2 in). If
the slack exceeds 30 mm ( 1.2 in), adjust.
a. 20 ~ 30 mm (0.8 ~ 1.2 in)
6-19
Drive chain slack checkNOTE:
Spin the wheel several times and find the tightest position
of the chain. Check and/or adjust the chain slack while it is
in this tightest position.
To check the chain slack the motorcycle must be held
straight up with both wheels on the ground and without rider.
Check the slack at the position shown in the illustration.
Normal slack is approximately 20 ~ 30 mm ( 0.8 ~ 1.2 in). If
the slack exceeds 30 mm ( 1.2 in), adjust.
a. 20 ~ 30 mm (0.8 ~ 1.2 in)

6-20
Drive chain slack adjustment
1. Locknut 2. Adjusting bolt
1. Loosen the rear brake pedal free play adjusting nut.
2. Loosen the axle nut.
3. Loosen the chain adjusting locknuts on each chain
puller. To tighten the chain, turn the chain adjusting nuts
in direction a .To loosen the chain turn the chain
adjusting nuts in direction b and push the wheel
forward. Turn each chain adjusting nut exactly the same
amount to maintain correct axle alignment. There are
marks on each chain puller. Use these marks to align
the rear wheel.Too little chain slack will overload the engine and other vital
parts. Keep the slack within the specified limits.
To maintain correct axle alignment, Ensure the notch on
the adjuster is on the same mark on left and right side
4. After adjusting, be sure to tighten each chain adjusting
locknut. The tighten the axle nut to the specified torque
Axle nut torque:
91 N.m (9.1 Kgf.m, 66 lbf.ft)
Locknut torque:
15 N.m (1.5 Kgf.m, 11 lbf.ft)
5. Adjust the free play in the brake pedal.
Check the operation of the brake light after adjusting
the rear brake.
CAUTION:
CAUTION:
6-20
Drive chain slack adjustment
1. Locknut 2. Adjusting bolt
1. Loosen the rear brake pedal free play adjusting nut.
2. Loosen the axle nut.
3. Loosen the chain adjusting locknuts on each chain
puller. To tighten the chain, turn the chain adjusting nuts
in direction a .To loosen the chain turn the chain
adjusting nuts in direction b and push the wheel
forward. Turn each chain adjusting nut exactly the same
amount to maintain correct axle alignment. There are
marks on each chain puller. Use these marks to align
the rear wheel.Too little chain slack will overload the engine and other vital
parts. Keep the slack within the specified limits.
To maintain correct axle alignment, Ensure the notch on
the adjuster is on the same mark on left and right side
4. After adjusting, be sure to tighten each chain adjusting
locknut. The tighten the axle nut to the specified torque
Axle nut torque:
91 N.m (9.1 Kgf.m, 66 lbf.ft)
Locknut torque:
15 N.m (1.5 Kgf.m, 11 lbf.ft)
5. Adjust the free play in the brake pedal.
Check the operation of the brake light after adjusting
the rear brake.
CAUTION:
CAUTION: