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:

    Storage
    Short-term Always store your motorcycle in a cool, dry place and, if necessary, protect it against dust with a porous cover. NOTICE Storing the motorcycle in a poorly ventilated room or covering it with a tarp, while it is still wet, will allow water and humidity to seep in and ...

    Checking the rear brake hose
    1. Check: Brake hoses "1" Cracks/damage/wear  Replace. 2. Check: Brake hose holder "2" Loose connection Tighten the holder bolt. Loose or open holder Fasten properly. 3. Hold the vehicle upright and apply the rear brake several times. 4. Check: Brake ho ...

    Fuel tank cap
    Fuel tank cap Fuel tank cap lock cover Unlock. To remove the fuel tank cap Open the fuel tank cap lock cover. Insert the key into the lock and turn it 1/4 turn counterclockwise. The lock will be released and the fuel tank cap can be removed. To install the fuel tank ca ...

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