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 and replacing the rear wheel sprocket
1. Check:
Rear wheel sprocket
More than 1/4 tooth "a" wear
Replace the
rear wheel sprocket.
Bent teeth Replace the rear
wheel sprocket.
b. Correct
1. Drive chain roller
2. Rear wheel sprocket
2. Replace:
Rear wheel sprocket
a. Remove the self-locking nuts and the ...
Adjusting the engine idling speed
NOTE:
Prior to adjusting the engine idling speed, the air
filter element should be clean, and the engine
should have adequate compression.
1. Start the engine and let it warm up for several
minutes.
2. Remove:
Rider seat
Refer to "GENERAL CHASSIS" on page 4-1.
3. Lift the fuel tank. ...
Checking the fuel pressure
1. Check:
Pressure regulator operation
a. Remove the fuel hose connector cover "1"
and disconnect the fuel hose "2" from the fuel
pump.
CAUTION:Although the fuel has been removed from
the fuel tank, be careful when removing the
fuel hose, since there may be fuel remaining
i ...