Yamaha YZF-R125 Service Manual: Fi system
The fuel pump delivers fuel to the fuel injector via the fuel filter. The pressure regulator maintains the fuel pressure that is applied to the fuel injector at only 250 kPa (2.50 kg/cm², 36.3 psi). Accordingly, when the energizing signal from the ECU energizes the fuel injector, the fuel passage opens, causing the fuel to be injected into the intake manifold only during the time the passage remains open. Therefore, the longer the length of time the fuel injector is energized (injection duration), the greater the volume of fuel that is supplied. Conversely, the shorter the length of time the fuel injector is energized (injection duration), the lesser the volume of fuel that is supplied.
The injection duration and the injection timing are controlled by the ECU. Signals that are input from the throttle position sensor, crankshaft position sensor, intake air pressure sensor, intake air temperature sensor, lean angle sensor and coolant temperature sensor enable the ECU to determine the injection duration. The injection timing is determined through the signals from the crankshaft position sensor. As a result, the volume of fuel that is required by the engine can be supplied at all times in accordance with the driving conditions.
- Fuel pump
- Fuel injector
- Ignition coil
- Coolant temperature sensor
- ECU (engine control unit)
- Lean angle sensor
- Crankshaft position sensor
- FID (fast idle solenoid)
- Air filter case
- Throttle body
- Throttle body sensor assembly
- Intake air temperature sensor
- Throttle position sensor
- Intake air pressure sensor
- Fuel system
- Air system
- Control system
Outline of the fi system
The main function of a fuel supply system is to provide fuel to the
combustion chamber at the optimum
air-fuel ratio in accordance with the engine operating conditions and the
atmospheric tempera ...
Multi-function display
1. Multi-function display
2. "RESET/SELECT" button
The multi-function display is equipped with the
following:
a speedometer (which shows the riding speed)
an odometer (which shows the t ...
Other materials:
Installing the generator
1. Install:
Woodruff key
Generator rotor
Washer
Generator rotor nut
NOTE:
Clean the tapered portion of the crankshaft and
the generator rotor hub.
When installing the generator rotor, make sure
the woodruff key is properly sealed in the keyway
of the crankshaft.
2. Tighte ...
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 ...
Be a Responsible Owner
As the vehicle's owner, you are responsible
for the safe and proper operation
of your motorcycle.
Motorcycles are single-track vehicles.
Their safe use and operation are dependent
upon the use of proper riding
techniques as well as the expertise of
the operator. Every operator should
...