Yamaha YZF-R125 Service Manual: Checking the horn
1. Check:
Horn resistance
Out of specification 
Replace.
a. Disconnect the horn connectors from the horn terminals.
b. Connect the pocket tester ( × 1) to the horn
terminals.
- Positive tester probe
horn terminal "1" - Negative tester probe
horn terminal "2"
c. Measure the horn resistance.
2. Check:
Horn sound
Faulty sound Adjust or replace.
a. Connect a battery (12 V) to the horn.
b. Turn the adjusting screw in direction "a" or "b" until the specified horn sound is obtained.
Checking the rectifier/regulator
1. Check:
Rectifier/regulator output voltage
Out of specification → Replace the
rectifier/
regulator.
a. Set the engine tachometer to the spark plug
lead.
b. Connect the pocket tester ...
Checking the fuel sender
1. Drain the fuel from the fuel tank.
2. Check:
Fuel sender resistance
Out of specification → Replace the fuel
sender.
a. Connect the pocket tester ( ×
10) to the fuel
sender c ...
Other materials:
Replacing a turn signal light bulb
Remove the turn signal light lens
by removing the screw.
Screw
Remove the burnt-out bulb by
pushing it in and turning it counterclockwise.
Insert a new bulb into the socket,
push it in, and then turn it clockwise
until it stops.
Install the lens by installing ...
Removing the swingarm
1. Stand the vehicle on a level surface.
WARNINGSecurely support the vehicle
so that there is
no danger of it falling over.
NOTE:
Place the vehicle on a suitable stand so that the
rear wheel is elevated.
2. Measure:
Swingarm side play
Swingarm vertical movement
a. Me ...
Disassembling the rear brake caliper
1. Remove:
Brake caliper piston "1"
Brake caliper piston dust seal "2"
Brake caliper piston seal "3"
a. Blow compressed air into the brake hose joint
opening "a" to force out the piston from the
brake caliper.
WARNING
Cover the brake caliper piston with a rag.
Be careful no ...