Troubleshooting

Overheating

~1min read

Engine

1. Clogged coolant passages

  • Cylinder head and piston
  • Heavy carbon buildup

2. Engine oil

  • Incorrect oil level
  • Incorrect oil viscosity
  • Inferior oil quality

Cooling system

1. Coolant

  • Low coolant level

2. Radiator

  • Damaged or leaking radiator
  • Faulty radiator cap
  • Bent or damaged radiator fin

3. Water pump

  • Damaged or faulty water pump
  • Thermostat
  • Thermostat stays closed
  • Hose(s) and pipe(s)
  • Damaged hose
  • Improperly connected hose
  • Damaged pipe
  • Improperly connected pipe

Fuel system

1. Throttle body

  • Damaged or loose throttle body joint

2. Air filter

  • Clogged air filter element

Chassis

1. Brake(s)

  • Dragging brake

Electrical system

1. Spark plug

  • Incorrect spark plug gap
  • Incorrect spark plug heat range

2. Ignition system

  • Faulty ECU

Overcooling

Cooling system

1. Thermostat

  • Thermostat stays open

Test yourself

A quick Yamaha YZF-R125 quiz: every answer comes with an explanation and a link to the manual page.