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:
Checking the steering head
1. Wash:
Bearings
Bearing races
2. Check:
Bearings
Bearing races
Damage/pitting →Replace.
3. Replace:
Bearings
Bearing races
a. Remove the bearing races from the steering
head pipe with a long rod "1" and hammer.
b. Remove the bearing race from the lower
bracket ...
Lubricating the drive chain
The drive chain consists of many interacting
parts. If the drive chain is not maintained properly,
it will wear out quickly. Therefore, the drive
chain should be serviced, especially when the
vehicle is used in dusty areas.
This vehicle has a drive chain with small rubber
O-rings between eac ...
Indicator and warning lights
Indicator and warning lights
Neutral indicator light""
Turn signal indicator light""
High beam indicator light""
Engine trouble warning light""
Coolant temperature warning light""
Turn signal indicator light""
This indicator light flashes when the
turn signal switch is pushed t ...