Fuel injection is the introduction of fuel into an internal combustion engine, most commonly automotive engines, by means of an injector.
All diesel engines use fuel injection by design. Gasoline engines can use direct gasoline injection, where the fuel is delivered directly to the combustion chamber, or indirect injection where the fuel mixes with the air before the intake stroke.
In gasoline engines, the fuel injection replaced the carburetors of the eighties. The main difference between carburetors and fuel injection is that the fuel injection atomizes the fuel through a small nozzle at high pressure, whereas a carburetor is based on the suction created by the accelerated intake air through a Venture tube to draw fuel into the air stream.
As a rule, internal combustion engines work best with air-to-fuel ratios floating in the range of 14.7 to 1. Although there is always a certain latitude, Leaner mixes tend to degrade performance, while the richer and Increases emissions, without substantially increasing yield. Because tilt adjustments create driving problems, motorcycles on pre-issue right days are usually set on the rich side. This enabled them to start, warm up quickly and provide good performance. It is true that the economy was not what it could have been and tail pipe emissions were off the charts, but at that time, gas was cheap and unregulated emissions. As long as the bicycle worked decently and the oil was not dripping from the pipes, no one cared how rich their jets were. All of that changed when the first motorcycle pollution laws were enacted in 1979. Initially, most OEMs simply bowed, but that led to other problems and it soon became apparent that a better solution was needed. At first, it seemed that the improved carburetors might be the answer and for a while it was. In fact, there are still plenty of carburetor bikes on the market that work well. Sadly these days are coming to an end, and here is why; Because carburetors rely on fixed orifice injectors, superimposed fuel circuits and cliometric pressure to deliver the correct fuel / air mixture, there is not much adaptability to them, at least until you break the screwdrivers and start to change things. Often a compromise between slightly slanted in some throttle openings and slightly rich in others. This leads to things like slow warm-ups, surges to small butterfly openings and emission outlets that are legal limit, and can be pushed over the edge by even the slightest adjustment or change in jet. On the other hand, electronic fuel injection systems employ a variety of sensors that tell a computer exactly what the engine is doing at any given time. After comparing that information with a set of parameters known as a map, the computer determines exactly how much fuel is required to maximize power while creating the lowest emissions, so the air / fuel ratio is adjusted accordingly. Whenever the map is spelled accurately, and with some small exceptions are usually pretty good, this allows the engine to receive the ideal mix in all circumstances, neither so thin it creates problems nor so rich that it exceeds emission standards, And that is why they have become the fuel supply system of choice in everything from scooters to super bikes.
How EFI Works
When a carburetor motor is running, the airflow creates a low pressure area in the venturi of the carburetor. Because the fuel in the flotation vessel is at atmospheric pressure while the pressure in the venturi is somewhat smaller, the fuel is forced through the metering jets into the venturi and from there is conveyed by the air flow. In summary, the fuel dosage depends on the size of the holes in the jets and the force of the vacuum signal on the venturi of the carburetor. Because the vacuum signal is affected by everything from engine rpm and throttle position to the condition of the rings and the type of exhaust system you are using, it is a crucial piece of the puzzle that can complicate the process Endless jet Of course, it's a great simplification of how a carburetor works, but it hits the high notes and hopefully gives you an idea why you need a very sophisticated carburetor to provide a really accurate fuel measurement. In a sense, electronic fuel injection is much simpler than a carburetor. Reduced to the essentials, an EFI system is nothing more than a nozzle that sprays gasoline into the air stream every time a computer tells it to. Of course, the devil is always in the details and the details, in particular the processes that the computer uses to determine how much fuel to supply can be quite complicated.
All electronic fuel injection systems operate in essentially the same way; Information on the operating status of the motors is transmitted to the computer via sensors. The team then compares that data with a stored map of fueling requirements. Once you find what you like, it tells the injector to stay open and spraying fuel for a certain period of time. Since the hardware is more or less the same, the actual difference between EFI systems is in the way the hardware is driven or mapped. Because we are primarily interested in V-Twin cruises here, we will limit the discussion to the most commonly used mapping in them, the Alpha-N system, which uses the throttle position to calculate the engine load and Speed system -Density, which The load by measuring the vacuum of the intake manifold.