YAMAHA YBR125 2003 Workshop Manual

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1. Engine oil filler cap
1. Maximum mark 2.Minimum mark
1
Engine oil
1. Oil level measurement
a. Place the motorcycle on a level place and hold it in anupright position. Warm up the engine for several
minutes.
NOTE:
Be sure the motorcycle is positioned straight up when
checking the oil level. A slight tilt toward the side can result
in false readings.
b. With the engine stopped, with the engine stopped, unscrew the oil filler cap/ dispstick and rest it on the
threads of the ok.
NOTE:
Wait a few minutes until the oil level settles before checking.
c. Remove the oil filler cap/ dispstick, clean it with a dry cloth and check the oil level.
NOTE:
To check the oil level the oil filler cap/ dispstick can not be
screwed, just lightly seated in place. d. The oil level should be between the maximum and
minimum marks. If the level is low, add oil to raise it to the
indicated level, check for oil leakage.
!!
1. Engine oil filler cap
1. Maximum mark 2.Minimum mark
1
Engine oil
1. Oil level measurement
a. Place the motorcycle on a level place and hold it in an
upright position. Warm up the engine for several
minutes.
NOTE:
Be sure the motorcycle is positioned straight up when
checking the oil level. A slight tilt toward the side can result
in false readings.
b. With the engine stopped, with the engine stopped, unscrew the oil filler cap/ dispstick and rest it on the
threads of the ok.
NOTE:
Wait a few minutes until the oil level settles before checking.
c. Remove the oil filler cap/ dispstick, clean it with a dry cloth and check the oil level.
NOTE:
To check the oil level the oil filler cap/ dispstick can not be
screwed, just lightly seated in place. d. The oil level should be between the maximum and
minimum marks. If the level is low, add oil to raise it to the
indicated level, check for oil leakage.

6-7
2. Engine oil and filter replacement
a. Warm up the engine for a few minutes.
b. Stop the engine. Place an oil pan under the engine andremove the dipstick.
c. Remove the drain plug and drain the oil.
d. Reinstall the drain plug, check if the gasket is damaged and lighten it to the specified torque.
Tightening torque:
Drain plug: 20 N.m (2.0 kgf.m, 14.5 lbf.t)
1.Dipstick
1. Engine oil drain plug
1
6-7
2. Engine oil and filter replacement
a. Warm up the engine for a few minutes.
b. Stop the engine. Place an oil pan under the engine andremove the dipstick.
c. Remove the drain plug and drain the oil.
d. Reinstall the drain plug, check if the gasket is damaged and lighten it to the specified torque.
Tightening torque:
Drain plug: 20 N.m (2.0 kgf.m, 14.5 lbf.t)
1.Dipstick
1. Engine oil drain plug
1

6-8
e. Fill engine with oil. Install the oil filter cap and tighten.
NOTE:
Recommended engine oil classification; API Service “SH”
type or equivalent
Do not put in any chemical additives. Engine oil also
lubricates the clutch and additives could cause clutch
slippage.
Be sure no foreign material enters the crankcase. f. Start the engine and warm up for a few minutes.While warming up, check for oil leakage. If oil
leakage is found, stop the engine immediately, and
check for the cause.
g. Stop the engine and check the oil level.
After replacing the engine oil, be sure to check the oil
pressure.
Oil quantity: Total amount:
1.2 L ( 0.264 Imp gal, 0.317 US gal)
Periodic oil change:
1.0 L ( 0.220 Imp gal, 0.264 US gal)
Recommended oil:
Yamalube 4
CAUTION:
CAUTION:
CAUTION:
6-8
e. Fill engine with oil. Install the oil filter cap and tighten.
NOTE:
Recommended engine oil classification; API Service “SH”
type or equivalent
Do not put in any chemical additives. Engine oil also
lubricates the clutch and additives could cause clutch
slippage.
Be sure no foreign material enters the crankcase. f. Start the engine and warm up for a few minutes.While warming up, check for oil leakage. If oil
leakage is found, stop the engine immediately, and
check for the cause.
g. Stop the engine and check the oil level.
After replacing the engine oil, be sure to check the oil
pressure.
Oil quantity: Total amount:
1.2 L ( 0.264 Imp gal, 0.317 US gal)
Periodic oil change:
1.0 L ( 0.220 Imp gal, 0.264 US gal)
Recommended oil:
Yamalube 4
CAUTION:
CAUTION:
CAUTION:

!$ Oil pressure1. Remove the check bolt 
 in the cylinder head.
2. Start the engine and keep it idling until oil flows out
of the bleed hole. If no oil comes out after one
minute, turn off the engine immediately so it will
not seize. In such a case go to the nearest Yamaha
dealer or other qualified mechanic for repairs.
3. After checking, tighten the check bolt to the
specified torque.
Check bolt torque:
7 N.m (0.7 Kgf.m, 5.0 lbf.ft)
1. Check bolt
1
!$ Oil pressure1. Remove the check bolt 
 in the cylinder head.
2. Start the engine and keep it idling until oil flows out
of the bleed hole. If no oil comes out after one
minute, turn off the engine immediately so it will
not seize. In such a case go to the nearest Yamaha
dealer or other qualified mechanic for repairs.
3. After checking, tighten the check bolt to the
specified torque.
Check bolt torque:
7 N.m (0.7 Kgf.m, 5.0 lbf.ft)
1. Check bolt
1

6-10Air filter
The air filter should be cleaned at the specified intervals.
It should be cleaned more frequently if you are riding in
unusually wet or dusty areas.
1. Remove the right side cover.(pag. 3-13)
2. Remove the air filter case cover by removing the bolts.
3. Remove the clamp.
4. Remove the air filter from the case.
6-10Air filter
The air filter should be cleaned at the specified intervals.
It should be cleaned more frequently if you are riding in
unusually wet or dusty areas.
1. Remove the right side cover.(pag. 3-13)
2. Remove the air filter case cover by removing the bolts.
3. Remove the clamp.
4. Remove the air filter from the case.

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.
!
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.
!
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.
!
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.
!
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.
!

Standard idle speed:
1,300 ~ 1,400 r/min
1. Throttle stop screw
Idle speed adjustment
1
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.
!

Standard idle speed:
1,300 ~ 1,400 r/min
1. Throttle stop screw
Idle speed adjustment
1

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.
!
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.
!
Free play: 3 ~ 7 mm (0.12 ~ 0.28 in)
Throttle cable adjustment
1. Free play
2. Locknut
3. Adjuster

!
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.
!
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.