Yamaha YZF-R125 Service Manual: Incorrect engine idling speed

Yamaha YZF-R125 Service Manual / Troubleshooting / Incorrect engine idling speed

Engine

1. Cylinder and cylinder head

  • Incorrect valve clearance
  • Damaged valve train components

2. Air filter

  • Clogged air filter element

Fuel system

1. Throttle body

  • Damaged or loose throttle body joint
  • Improperly adjusted engine idling speed (idle adjusting screw)
  • Improper throttle cable free play
  • Flooded throttle body
  • Faulty air induction system

Electrical system

1. Battery

  • Discharged battery
  • Faulty battery

2. Spark plug

  • Incorrect spark plug gap
  • Incorrect spark plug heat range
  • Fouled spark plug
  • Worn or damaged electrode
  • Worn or damaged insulator
  • Faulty spark plug cap

3. Ignition coil

  • Broken or shorted primary or secondary coils
  • Faulty spark plug lead
  • Cracked or broken ignition coil

4. Ignition system

  • Faulty ECU
  • Faulty crankshaft position sensor
  • Broken generator rotor woodruff key
    Starting failures
    Engine 1. Cylinder and cylinder head - Loose spark plug - Loose cylinder head or cylinder - Damaged cylinder head gasket - Damaged cylinder gasket - Worn or damaged cylinder - Incorrect valve c ...

    Poor medium-and-high-speed performance
    Refer to "STARTING FAILURES" on page 9-1. Engine 1. Air filter Clogged air filter element Fuel system 1. Fuel pump Faulty fuel pump Faulty gear shifting Shifting is difficult Refer ...

    Other materials:

    Sidestand
    The sidestand is located on the left side of the frame. Raise the sidestand or lower it with your foot while holding the vehicle upright. TIP The built-in sidestand switch is part of the ignition circuit cut-off system, which cuts the ignition in certain situations. WARNING The vehicl ...

    Checking the coolant temperature sensor
    1. Remove: Coolant temperature sensor WARNING Handle the coolant temperature sensor with special care. Never subject the coolant temperature sensor to strong shocks. If the coolant temperature sensor is dropped, replace it. 2. Check: Coolant temper ...

    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 ...

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