Yamaha YZF-R125 Service Manual: Checking the relays
Check each switch for continuity with the pocket
tester. If the continuity reading is incorrect, replace
the relay. 
1. Disconnect the relay from the wire harness.
2. Connect the pocket tester ( × 1) and battery (12 V) to the relay terminal as shown.
Check the relay operation.
Out of specification → Replace.
Starter relay
1. Positive battery terminal
2. Negative battery terminal
3. Positive tester probe
4. Negative tester probe
Starting circuit cut-off relay
1. Positive battery terminal
2. Negative battery terminal
3. Positive tester probe
4. Negative tester probe 
Headlight relay
1. Positive battery terminal
2. Negative battery terminal
3. Positive tester probe
4. Negative tester probe 
Radiator fan motor relay
1. Positive battery terminal
2. Negative battery terminal
3. Positive tester probe
4. Negative tester probe
Checking and charging the battery
WARNINGBatteries generate explosive hydrogen gas
and contain electrolyte which is made of poisonous
and highly caustic sulfuric acid.
Therefore, always follow these preventive
mea ...
Checking the turn signal relay
1. Check:
Turn signal relay input voltage
Out of specification →The wiring circuit
from
the main switch to the turn signal relay coupler
is faulty and must be repaired.
a. Connect the poc ...
Other materials:
Checking the brake fluid level
Front brake
Front brake
Minimum level mark
Rear brake
Rear brake
Minimum level mark
Insufficient brake fluid may allow air to
enter the brake system, possibly causing
it to become ineffective.
Before riding, check that the brake fluid
is above the minimum level mark an ...
Checking the shift forks
The following procedure applies to all of the shift
forks.
1. Check:
Shift fork cam follower "1"
Shift fork pawl "2"
Bends/damage/scoring/wear
Replace the
shift fork.
2. Check:
Shift fork guide bar
Roll the shift fork guide bar on a flat surface.
Bends Replace. ...
Checking the starter clutch
1. Check:
Starter clutch rollers "1"
Starter clutch spring caps "2"
Starter clutch springs "3"
Damage/wear Replace the starter
clutch
assembly.
2. Check:
Starter clutch idle gear
Starter clutch gear
Burrs/chips/roughness/wear Replace the
defective part(s).
3. Check:
...