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:

Chain drive
Removing the drive chain 1. Stand the vehicle on a level surface. WARNINGSecurely support the vehicle so that there is no danger of it falling over. NOTE: Place the vehicle on a suitable stand so that the rear wheel is elevated. ...

Checking the engine oil level
1. Stand the vehicle on a level surface. NOTE: Place the vehicle on a suitable stand. Make sure the vehicle is upright. 2. Start the engine, warm it up for several minutes, and then turn it off. 3. Check: Engine oil level The engine oil level should be between the minimum level ...

Checking the water pump
1. Check: Water pump housing cover Water pump housing Cracks/damage Replace. Impeller shaft Cracks/damage/wear Replace. Bearing Rough movement Replace. Radiator outlet hose Cracks/damage Replace. ...