ELECTRONIC FUEL INJECTION (EFI)

Type of fuel system is a step injection of innovation that are being developed to be applied to the bicycle machine. This type of injection is already applied to the bicycle in a limited number of machines in the 1980s, starting with a mechanical injection system evolved into the electronic injection system. Mechanical injection system is also called continuous injection system (K-Jetronic) because the injector is continuously sprayed into each inlet (intake manifolds). While electronic injection system or better known as Electronic Fuel Injection (EFI), the volume and time Injenction done electronically. EFI System sometimes referred to as EFI (Electronic Gasoline Injection), EPI (Electronic Gasoline Injection), PGM-FI (Programmed Fuel Injenction) and Engine Management. The use of fuel injection systems on the bike commercial engine in Indonesia has started to be developed. One example is on one type of production Astra Honda engine, which is the Supra X 125. Term EFI system on the Honda PGM-FI (Programmed Fuel Injection) or the fuel system has been programmed. In general, the replacement of conventional fuel systems to the EFI system is intended to increase performance and engine power a better, more stable acceletation at every turn the engine, fuel consumption is economical, and produce emissions that the exhaust gases so that less can be more friendly to the environment. In addition, the excess of the engine with fuel injection type is more easily turned on at the moment not been used, and not affected at temperatures in the environment.

1. EFI System Working Principle
The term fuel injection system (EFI) can be described as a distributed system using a fuel pump at a certain pressure to mix with the incoming air into the engine. On EFI system with a gasoline engine, in general, fuel injection process occurs at the end of the intake manifold / manifold before the inlet valve in. (valve / spigot entry). At the inlet valve is open, is the suction stroke, the incoming air into the engine is mixed with fuel. Ideally, EFI systems must be able to supply some fuel that is sprayed in order to mix with air in a ratio appropriate to mix spin conditions and engine load, engine temperature conditions and atmospheric temperature at the time. The system must be able to supply the amount of fuel varied, so that changes in engine operating conditions can be achieved with engine performance remains optimal.

2. Basic Construction EFI System
In general, construction EFI system can be divided into three sections / main systems, namely: a) fuel system (fuel system), b) electronic control systems (electronic control system), and c) induction system / influent (water induction system ). These three main systems will be discussed individually below. The number of components found in different bias EFI system on each type of bike engines. The more complete EFI system components are used, of course EFI system will work better
so could result in engine performance is more optimal as well. With more complete components EFI systems, then the necessary correction settings to set the ratio of fuel and air in accordance with the engine working conditions will be more perfect. The figure below shows an example of the circuit scheme of Yamaha EFI system GTS1000 and placement of components on the EFI system Honda Supra X 125.

Picture 1. Schematic circuit GTS1000 Yamaha EFI system

Description number in the image:
1. Fuel rail / delivery pipe
2. Pressure regulator
3. Injector
4. Air box
5. Water temperature sensor
6. Throttle body butterfly
7. Fast idle system
8. Throttle position sensor
9. Engine coolant temperature sensor
10. Crankshaft position sensor
11. Camshaft position sensor
12. Oxygen (lambda) sensor
13. Catalytic converter
14. Intake air pressure sensor
15. ECU (Electronic control unit)
16. Ignition coil
17. Atmospheric Pressure Sensor