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"

Checking the speed sensor


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 lubricating the sidestand
    Checking and lubricating the sidestand The operation of the sidestand should be checked before each ride, and the sidestand pivot and metal-to-metal contact surfaces should be lubricated if necessary. WARNING If the sidestand does not move up and down smoothly, have a Yamaha deal ...

    Engine specifications
    ...

    Disassembling the front fork legs
    The following procedure applies to both of the front fork legs. 1. Remove: Rubber cap Clip "1" Front fork cap "2" (with O-ring) Fork spring NOTE: Push the front fork cap in the direction of the arrow shown in the illustration to remove the clip. 2. Drain: Fork oil NOTE ...

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