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:
Shifting
Shifting
Shift pedal
Neutral position
Shifting gears lets you control the
amount of engine power available for
starting off, accelerating, climbing hills,
etc.
The gear positions are shown in the illustration.
TIP
To shift the transmission into the neutral
position, press the ...
Installing the front wheel (disc)
1. Install:
Front brake disc
NOTE:
Be sure to install the front brake disc with the
arrow mark "a" on the disc facing out.
Tighten the brake disc bolts in stages and in a
crisscross pattern.
2. Check:
Front brake disc
Refer to "CHECKING THE FRONT BRAKE
DISC" on page 4 ...
Checking the valve seats
The following procedure applies to all of the
valves and valve seats.
1. Eliminate:
Carbon deposits
(from the valve face and valve seat)
2. Check:
Valve seat
Pitting/wear Replace the
cylinder head.
3. Measure:
Valve seat width C "a"
Out of specification Replace
the ...