About engine tuning

Engine tuning is a demanding technical field which includes a wide range of modifications to the engine and its accessories. In the case of Harley-Davidson motorcycles, the robust construction of the traditional V-Twin engine increases the wide range of modification options. However, this is not the main reason for the popularity of H-D engine tuning. It was the specific culture of the Harley-Davidson riders that significantly enriched the goals of tuning. The following description is not intended for very specific tuning of high-performance engines and supercharged engines for racing purposes where riding comfort in cruising modes and engine life is not the goal. A significant portion of the information below is generally valid, but we will only be dealing with engines with electronic fuel injection system (EFI- DELPHI).

In the following description, we will try to gradually describe and analyse the situation from scratch. Many of the experienced readers will be taken aback by some obvious information, or they will wonder about some simplifications that we will use, even intentionally. Our goal is not to provide deep technical information specifying all the functions of the H-D EFI system. Our aim is to show the directions, especially to those engine specialists who have an excellent knowledge about H-D bikes with carbureted engines, how to tune the EFI system for the same performance levels of a carbureted engine.

In 2011 ACTIA CZ (ATAL) first developed and started selling the Diag4Bike diagnostic system which has gained a global reputation as a first class diagnostic scan tool. The Diag4Bike can be compared to the factory device used by the Harley-Davidson0174® dealer network. It is available in many languages, affordable and extremely user-friendly.

Our next big step was in 2013, when we completed the development and launched a tuning tool for Harley-Davidson® engines. This new tuning tool is the Diag4Tune™ program which is part of the Diag4Bike™ diagnostic program as of version V12. As before, our goal was to design a tool with a simple structure, combining ease of use with maximum help in tuning. The main advantage of this system is that there is no need to mount anything to the motorcycle. All changes to the maps (fuel, ignition advance, RPM limiter etc.) are performed directly in the Electronic Control Module (ECM) via the diagnostic connector. Before starting the tuning, the original configuration of the bike's electronic control module is backed up, so it is always possible to revert to the original condition of the engine within a matter of seconds.

If there is anything you don't understand in the following text please feel free to contact us. We welcome your comments and will do our best to answer any questions you might have info@actia.cz

Josef Hořejší
Josef Hořejší