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Posted by on in Dyno Tuning

Hello to any and all who have visited this website and blog! I will be using this section of the website for your convenience in subjects pertaining to the V-Twin world. I hope to shed some light on various aspects of performance and maintenance as well as spur discussion on hot topics pertaining to the same. I invite each of you who come here to chime in and give your input on the topics posted here as well. This place is dedicated to learning, educating and discussing. Here we go!



Dyno tuning: The first topic I'm going to engage is dyno tuning and what it is. Essentially, a dynomometer (dyno) is a treadmill, if you will, used to analyze the efficiency of the combustion process and the performance of your motorcycle. The dyno I use here at IMS (Independent Motorcycle Shop, LLC) has a power absorption unit sometimes referred to as a eddy current brake. This brake is controlled through the dyno's computer and puts a load on your bikes engine so we can see how the combustion process is occurring in all phases and conditions your bike encounters throughout its life. With today's technologically advanced Electronic Fuel Injection (EFI) systems, we have almost infinite adjust-ability. Your Harley-Davidson's stock ECM (Electronic Control Module) is very powerful in terms of it's capabilities to supply your EFI bike with the correct amount of fuel and spark. It takes many things into account when supplying these two things. Some of the things it takes into consideration are engine temperature, manifold pressure, rpm, vehicle speed and throttle position. With the dyno, we can monitor the engines efficiency and create different scenarios your engine will see while you are riding. We sample the combustion process during the different conditions I just went over and by using a tuning interface such as a SERT or Screamin' Eagle Race Tuner, TTS MasterTune or other device to alter the ECM's parameters so that your engine gets exactly what it wants, precisely when it needs it to perform to the best of it's abilities under any condition with the components your bike has.

What's different about the dyno we use compared to other dyno's? We use a Factory Pro dyno. Probably the biggest thing that sets a Factory Pro dyno apart from other dyno's such as a Dynojet or SuperFlow is that I use a 4 gas analyzer to sample and read the combustion process. This gives me more information about what your bike wants to perform better. A good dyno tune is just as important if not more than say, cams, air cleaner, head work, exhaust or other common modifications that are done on the typical Harley motorcycle today. Furthermore, the money you spend on these modifications cannot be used to the best potential without a good dyno tune. In essence, the hard earned money you spend to get better performance out of your bike is not fully realized unless the combustion process is at its best potential. Other great reasons for investing in a good dyno tune are the longevity of your bike. When your engine is getting what it wants and needs, it can greatly increase the life of the engine as well as get good fuel economy and give you power at the twist of the wrist. The 4 gas analyzer or EGA (exhaust gas analyzer) reads HC (hydrocarbons) which is raw fuel, CO (Carbon Monoxide), CO2 (Carbon Dioxide) and O2 (Oxygen). These 4 gases tell me where and how much to adjust the fuel and the spark. Other dyno's typically read AFR or air fuel ratio. Essentially, they read residual (left over) oxygen after combustion has happened to determine the air fuel ratio being introduced to the combustion process. In either form of dyno testing and tuning, a constant supply of fresh air that has not already been through the combustion process is imperative! If emissions from the exhaust go back through the air intake and into the combustion process, the samples acquired are inaccurate and will result in a less than professional tune and leave more to be desired for the engine and the rider. This lack of fresh air during the tuning and sampling process is something I see in many facilities. The fans required to provide ample fresh air supply are expensive. Maybe that's part of the reason this is overlooked by many. Another point I'd like to make is that there is a difference in a tune and a dyno! Simply tweaking the cruise range or wide open throttle positions is more of a "dyno run" in my opinion than a tune. To sample all of the required areas to achieve a tune and give your bike what it wants and what you deserve takes time. It's not something that can possibly be done in and hour or so. If you take your bike in for a dyno tune, you should appreciate the fact that the dyno operator might want to spend several hours with your bike and not just a couple of hours with it. That being said, I will say, some tunes do go faster than others and a couple of things come into play here. One is the tuning device being used and another is how close the tune is before the tuning process is started. A tune takes time because there is so much adjust-ability and also because after changes have been made, more sampling is required to see if the desired effects have been achieved.  



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