Yamaha YZF-R125 Service Manual: Installing the thermostat

1. Install:

  • Thermostat

NOTE:

Install the thermostat with its breather hole "a" facing up.


2. Install:

  • Copper washer

  • Coolant temperature sensor

CAUTION:

Use extreme care when handling the coolant temperature sensor. Replace any part that was dropped or subjected to a strong impact.

3. Fill:

  • Cooling system (with the specified amount of the recommended coolant) Refer to "CHANGING THE COOLANT" on page 3-15.

4. Check:

  • Cooling system Leaks Repair or replace any
    faulty part.

5. Measure:

  • Radiator cap opening pressure Below the specified pressure 
    Replace the radiator cap.

    Refer to "CHECKING THE RADIATOR" on page 6-3.

    Checking the thermostat
    1. Check: Thermostat Does not open at 80.5-83.5 C (176.9-182.3 F)  Replace. a. Suspend the thermostat "1" in a container "2" filled with water. b. Slowly heat the water "3". c. ...

    Water pump
    ...

    Other materials:

    Checking the drive sprocket
    1. Check: Drive sprocket More than 1/4 tooth "a" wear Replace the drive chain sprockets as a set. Bent teeth Replace the drive chain sprockets as a set. b. Correct 1. Drive chain roller 2. Drive chain sprocket Checking the rear wheel sprocket Refer to "CHECKING AND R ...

    Adjusting the throttle cable free play
    Throttle cable free play The throttle cable free play should measure 3.0-5.0 mm (0.12-0.20 in) at the throttle grip. Periodically check the throttle cable free play and, if necessary, adjust it as follows. TIP The engine idling speed must be correctly adjusted before checkin ...

    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 coupler as shown. Positive tester probe sky blue "1" Negative tester probe orange/white " ...

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