service YAMAHA YBR125 2003 User Guide

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:

Brake fluid replacement
1. Complete fluid replacement should be done only bytrained service personnel.
2. Have a Yamaha dealer replace the following components during periodic maintenance or when they
are damaged or leaking.
a. Replace all rubber seals every two years.
b. Replace all hoses every four years.
!%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 locknut at the handlebar.
2. Turn the adjuster in or out until proper lever free play is
obtained.
3. Tighten the locknut.
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. Locknut 2. Adjuster a. 10 ~ 15 mm (0.4 ~ 0.6 in)
Brake fluid replacement
1. Complete fluid replacement should be done only by trained service personnel.
2. Have a Yamaha dealer replace the following components during periodic maintenance or when they
are damaged or leaking.
a. Replace all rubber seals every two years.
b. Replace all hoses every four years.
!%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 locknut at the handlebar.
2. Turn the adjuster in or out until proper lever free play is
obtained.
3. Tighten the locknut.
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. Locknut 2. Adjuster a. 10 ~ 15 mm (0.4 ~ 0.6 in)

6-23 Drive chain lubrication
The chain consists of many parts which work with each
other. If the chain is not maintained properly, it will wear out
quickly. Therefore, the chain must be serviced regularly.
This service is especially necessary when riding in dusty
areas.
1. Use Yamaha Chain and Cable Lube or any
brands of spray-type chain lubricant. First,
remove all dirt and mud from the chain with a
brush or cloth, then spray lubricant between both
rows of side plates and on all center rollers. The
chain should be lubricated every 500 km (300 mi).
2. To clean the chain, remove it from the machine,
dip it in solvent, and clean out as much dirt as
possible. Take the chain out of the solvent and
dry it. Immediately lubricate the chain to prevent
it from rusting.Cable inspection and lubrication
Damage to the outer housing of cables may allow
internal rusting and cause interfere with cable
movement. Replace damaged cables as soon as
possible to prevent unsafe conditions.
Lubricate the inner cable and the cable end. If it does not
operate smoothly, ask a Yamaha dealer to replace them.
RECOMMENDED LUBRICANT:
Engine oil SAE 20W50
WARNING:
6-23 Drive chain lubrication
The chain consists of many parts which work with each
other. If the chain is not maintained properly, it will wear out
quickly. Therefore, the chain must be serviced regularly.
This service is especially necessary when riding in dusty
areas.
1. Use Yamaha Chain and Cable Lube or any
brands of spray-type chain lubricant. First,
remove all dirt and mud from the chain with a
brush or cloth, then spray lubricant between both
rows of side plates and on all center rollers. The
chain should be lubricated every 500 km (300 mi).
2. To clean the chain, remove it from the machine,
dip it in solvent, and clean out as much dirt as
possible. Take the chain out of the solvent and
dry it. Immediately lubricate the chain to prevent
it from rusting.Cable inspection and lubrication
Damage to the outer housing of cables may allow
internal rusting and cause interfere with cable
movement. Replace damaged cables as soon as
possible to prevent unsafe conditions.
Lubricate the inner cable and the cable end. If it does not
operate smoothly, ask a Yamaha dealer to replace them.
RECOMMENDED LUBRICANT:
Engine oil SAE 20W50
WARNING:

6-33
It is advisable to have a Yamaha dealer service the
wheel.
Securely support the motorcycle so there is no danger
of it falling over. Front wheel removal
1. Place the motorcycle on the centerstand.
2. Remove the speedometer cable.
3. Remove the axle nut and axle.
NOTE:
Do not depress the brake lever when the disc is off the
caliper as the brake pads will be forced shut.
1. Axle nut 2. Speedometer cable
CAUTION:
6-33
It is advisable to have a Yamaha dealer service the
wheel.
Securely support the motorcycle so there is no danger
of it falling over. Front wheel removal
1. Place the motorcycle on the centerstand.
2. Remove the speedometer cable.
3. Remove the axle nut and axle.
NOTE:
Do not depress the brake lever when the disc is off the
caliper as the brake pads will be forced shut.
1. Axle nut 2. Speedometer cable
CAUTION:

6-35
3
21
Rear wheel removal
It is advisable to have a Yamaha dealer service the
wheel.
Securely support the motorcycle so there is no danger
of it falling over.
1. Place the motorcycle on the centerstand.
2. Remove the cotter pin and nut. Then remove the tension
bar from the brake shoe plate.3. Remove the brake adjusting nut and brake rod from
the brake cam lever.
4. Remove the axle nut and axle.
5. Remove the wheel assembly.
1. Nut 2. Cotter pin3. Tension bar
CAUTION:
1. Adjusting Nut 2. Brake Rod 3. Axle Nut
6-35
3
21
Rear wheel removal
It is advisable to have a Yamaha dealer service the
wheel.
Securely support the motorcycle so there is no danger
of it falling over.
1. Place the motorcycle on the centerstand.
2. Remove the cotter pin and nut. Then remove the tension
bar from the brake shoe plate.3. Remove the brake adjusting nut and brake rod from
the brake cam lever.
4. Remove the axle nut and axle.
5. Remove the wheel assembly.
1. Nut 2. Cotter pin3. Tension bar
CAUTION:
1. Adjusting Nut 2. Brake Rod 3. Axle Nut

6-36
Rear wheel installation
When installing the rear wheel, reverse the removal
procedures. Pay attention to the following points:
1. Adjust the drive chain.
2. Tighten the axle nut and the tension bar nut to the
specified tightening torque.
Axle nut torque: 91 N.m ( 9.1 Kgf.m, 66 lbf.ft)
Tension bar nut: 19 N.m (1.9 Kgf.m, 14 lbf.ft)
3. Adjust the rear brake.
Check the operation of the brake light after adjusting the
rear brake Troubleshooting
Although Yamaha motorcycles receive a rigid inspection
before shipment from the factory, trouble may occur during
operation. Any problem in the fuel, compression, or ignition
systems can cause poor starting and loss of power. The
troubleshooting chart describes a quick, easy, procedure
for making checks. If your motorcycle requires any repair,
bring it to a Yamaha dealer. The skilled technicians at a
Yamaha dealership have the tools, experience, and know-
how to properly service your motorcycle. Use only genuine
Yamaha parts on your motorcycle. Imitation parts may look
like Yamaha parts, but they are often inferior. Consequently,
they have a shorter service life and can lead to expensive
repair bills.
CAUTION:
6-36
Rear wheel installation
When installing the rear wheel, reverse the removal
procedures. Pay attention to the following points:
1. Adjust the drive chain.
2. Tighten the axle nut and the tension bar nut to the
specified tightening torque.
Axle nut torque: 91 N.m ( 9.1 Kgf.m, 66 lbf.ft)
Tension bar nut:
19 N.m (1.9 Kgf.m, 14 lbf.ft)
3. Adjust the rear brake.
Check the operation of the brake light after adjusting the
rear brake Troubleshooting
Although Yamaha motorcycles receive a rigid inspection
before shipment from the factory, trouble may occur during
operation. Any problem in the fuel, compression, or ignition
systems can cause poor starting and loss of power. The
troubleshooting chart describes a quick, easy, procedure
for making checks. If your motorcycle requires any repair,
bring it to a Yamaha dealer. The skilled technicians at a
Yamaha dealership have the tools, experience, and know-
how to properly service your motorcycle. Use only genuine
Yamaha parts on your motorcycle. Imitation parts may look
like Yamaha parts, but they are often inferior. Consequently,
they have a shorter service life and can lead to expensive
repair bills.
CAUTION: