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:

Installing the rear brake caliper
1. Install: Brake caliper "1" Copper washers Brake hose "2" Union bolt "3" WARNINGProper brake hose routing is essential to insure safe vehicle operation. Refer to "CABLE ROUTING" on page 2-33. CAUTION:When installing the brake hose onto the brake calip ...

Unstable handling
Handlebars - Bent or improperly installed right handlebar - Bent or improperly installed left handlebar 1. Steering head components - Improperly installed upper bracket - Improperly installed lower bracket (improperly tightened ring nut) - Bent steering stem - Damaged ball bearing or bearing ...

Checking and lubricating the sidestand
Checking and lubricating the sidestand The operation of the sidestand should be checked before each ride, and the sidestand pivot and metal-to-metal contact surfaces should be lubricated if necessary. WARNING If the sidestand does not move up and down smoothly, have a Yamaha deal ...