Yamaha YZF-R125 Service Manual: 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. Place a thermometer "4" in the water.

d. While stirring the water, observe the thermostat and thermometer's indicated temperature.

Checking the thermostat


A. Fully closed

B. Fully open

NOTE:

If the accuracy of the thermostat is in doubt, replace it. A faulty thermostat could cause serious overheating or overcooling.

2. Check:

  • Thermostat cover Cracks/damage Replace.

3. Check:

  • Radiator inlet hose Cracks/damage  Replace.

    Thermostat
    ...

    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 ...

    Other materials:

    Removing the throttle body
    1. Extract the fuel in the fuel tank through the fuel tank filler hole with a pump. 2. Disconnect: Fuel hose WARNINGCover the fuel hose connections with a cloth when disconnecting them. Residual pressure in the fuel lines could cause fuel to spurt out when removing the h ...

    Checking the oil pump
    1. Check: Oil pump drive gear Oil pump driven gear Oil pump housing Oil pump housing cover Cracks/damage/wear Replace the defective part(s). 2. Measure: Inner-rotor-to-outer-rotor-tip clearance "a" Outer-rotor-to-oil-pump-housing clearance "b" - Oil-pump-housing-to-inn ...

    Installing the primary drive gear and balancer gears
    1. Install: Balancer driven gear "1" Lock washer Balancer drive gear "2" Primary drive gear Washer "3" Balancer driven gear nut Primary drive gear nut NOTE: Align the punch mark "a" in the balancer drive gear "2" with the punch mark "b" in the balancer driven gear "1". ...

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