Harley-Davidson introduced electronic fuel injection (EFI) to its product line in 1995. since then, slowly but surely with the factory has the equipping and the evolution towards a more model with EFI. Starting in 2007, all Harley models equipped with EFI, including Sporty for the first time. With the impetus for migration to EFI is to meet the demands of the federal emissions standards that apply in California in 2006 and 2008 for 49 other countries. EFI reduces fuel Emissions because it meters fuel more accurately than a carburetor. It also offers street Riders the benefits of improved cold or hot starting, crisper acceleration under varied operating conditions, and smoother running at high altitudes.
Nonetheless, as with most things in life, there is no free lunch. EFI is more complex than carburetion and often requires increased costs for a serious performance induction package (parts and tuning). In fact, many engine builders are constantly searching for the Holy Grail-the perfect EFI "map" for their performance engine combination. For these reasons, some performance manufacturers offer custom EFI maps for specific performance parts combinations. However, if you deviate slightly from the exact parts combination or the planets align unfavorably, EFI tuning can get dicey. For those reasons, it is helpful to know a few basics about electronic fuel injection and some of the tuning aids available.
To better understand electronic fuel injection, it helps to understand some carburetor basics. With a carbureted engine, you have a main fuel tank and a carburetor mounted to an intake manifold, which in turn is mounted to the cylinder heads. The carburetor includes a venturi, fuel and air jets, and a butterfly. Airflow is regulated through the induction tract by the carburetor butterfly. As air flows through the venturi, it creates a low-pressure area at the venturi. At the same time, fuel is gravity-fed from the motorcycle's main fuel tank to the carb's float bowl, or fuel storage area.
Fuel jets then meter approximately the correct amount of fuel based on the vacuum signal at the venturi. The number of tuning jets used varies depending on the carb design, but simple carbs generally include three jets or circuits (idle jet, low-speed jet, and high-speed or main jet), while complex carbs have more. To tune a carb, one simply replaces a jet with a larger (richer) or smaller (leaner) jet, turns a screw either in or out, substitutes a tapered needle with another, or drills or plugs various fuel or air orifices. As such, carburetor tuning is straightforward and uses tangible items such as jets, screws, and needles for tuning. Additionally, simple tools such as the common screwdriver are typically used for adjustments.
Nonetheless, as with most things in life, there is no free lunch. EFI is more complex than carburetion and often requires increased costs for a serious performance induction package (parts and tuning). In fact, many engine builders are constantly searching for the Holy Grail-the perfect EFI "map" for their performance engine combination. For these reasons, some performance manufacturers offer custom EFI maps for specific performance parts combinations. However, if you deviate slightly from the exact parts combination or the planets align unfavorably, EFI tuning can get dicey. For those reasons, it is helpful to know a few basics about electronic fuel injection and some of the tuning aids available.
To better understand electronic fuel injection, it helps to understand some carburetor basics. With a carbureted engine, you have a main fuel tank and a carburetor mounted to an intake manifold, which in turn is mounted to the cylinder heads. The carburetor includes a venturi, fuel and air jets, and a butterfly. Airflow is regulated through the induction tract by the carburetor butterfly. As air flows through the venturi, it creates a low-pressure area at the venturi. At the same time, fuel is gravity-fed from the motorcycle's main fuel tank to the carb's float bowl, or fuel storage area.
Fuel jets then meter approximately the correct amount of fuel based on the vacuum signal at the venturi. The number of tuning jets used varies depending on the carb design, but simple carbs generally include three jets or circuits (idle jet, low-speed jet, and high-speed or main jet), while complex carbs have more. To tune a carb, one simply replaces a jet with a larger (richer) or smaller (leaner) jet, turns a screw either in or out, substitutes a tapered needle with another, or drills or plugs various fuel or air orifices. As such, carburetor tuning is straightforward and uses tangible items such as jets, screws, and needles for tuning. Additionally, simple tools such as the common screwdriver are typically used for adjustments.
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