Yamaha YZF-R125 Service Manual: Checking the speed sensor
1. Check:
Speed sensor output voltage
Out of specification → Replace.
a. Connect the pocket tester (DC 20 V) to the
speed sensor coupler (wire harness end) as
shown.
- Positive tester probe gray "1"
- Negative tester probe gray/black "2"
b. Set the main switch to "ON".
c. Elevate the front wheel and slowly rotate it.
d. Measure the voltage of gray and gray/black.
With each full rotation of the front wheel, the voltage reading should cycle from 0 V to 5.0 V to 0 V to 5.0 V.
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 ...
Checking the radiator fan motor
1. Check:
Radiator fan motor
Faulty/rough movement → Replace.
a. Disconnect the radiator fan motor coupler
from the wire harness.
b. Connect the battery (DC 12 V) as shown.
Posi ...
Other materials:
Checking the decompression system
1. Check:
Decompression system
a. Check the decompression system with the
camshaft sprocket and the decompression
cam installed to the camshaft.
b. Check that the decompression lever "1"
moves smoothly.
c. Without operating the decompression lever,
check that the decompression cam " ...
Checking the throttle body joint and air filter case joint
1. Remove:
Right lower side cowling
Left lower side cowling
Refer to "GENERAL CHASSIS" on page 4-1.
2. Check:
Throttle body joint "1"
Air filter case joint "2"
Cracks/damage Replace.
3. Install:
Right lower side cowling
Left lower side cowling
Refer to "GENERAL CHAS ...
Checking the rear brake hose
1. Check:
Brake hoses "1"
Cracks/damage/wear
Replace.
2. Check:
Brake hose holder "2"
Loose connection Tighten the
holder bolt.
Loose or open holder Fasten
properly.
3. Hold the vehicle upright and apply the rear
brake several times.
4. Check:
Brake ho ...