Yamaha YZF-R125 Service Manual: 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 shock absorber assembly
1. Install:
Rear shock absorber assembly
Relay arm "1"
NOTE:
Install the relay arm as shown in the illustration.
2. Tighten:
Rear shock absorber assembly upper nut
Relay arm nut
Rear shock absorber assembly lower nut
3. Install:
Connecting arms
NOTE:
When ins ...
Adjusting the engine idling speed
NOTE:
Prior to adjusting the engine idling speed, the air
filter element should be clean, and the engine
should have adequate compression.
1. Start the engine and let it warm up for several
minutes.
2. Remove:
Rider seat
Refer to "GENERAL CHASSIS" on page 4-1.
3. Lift the fuel tank. ...
Troubleshooting
Any of the following fail to light: headlight, high beam indicator light,
taillight, license plate light, auxiliary
light or meter light.
NOTE:
Before troubleshooting, remove the following part(s):
1. Seats
2. Fuel tank
...