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:

    Main switch/steering lock
    Main switch/steering lock The main switch/steering lock controls the ignition and lighting systems, and is used to lock the steering. The various positions are described below. ON All electrical circuits are supplied with power, the meter lighting, taillight, license plate light and ...

    Installing the generator
    1. Install: Woodruff key Generator rotor Washer Generator rotor nut NOTE: Clean the tapered portion of the crankshaft and the generator rotor hub. When installing the generator rotor, make sure the woodruff key is properly sealed in the keyway of the crankshaft. 2. Tighte ...

    Checking the ignition coil
    1. Check: Primary coil resistance Out of specification  Replace. a. Disconnect the ignition coil connectors from the ignition coil terminals. b. Connect the pocket tester ( × 1) to the ignition coil as shown. Positive tester probe red/white "1" Negative tester probe orange ...

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