Winter 2002

In todayís high tech world we are beginning to see sophisticated engine management systems fitted as standard to many motorcycles with emphasis on improved economy, increased performance and reduced emissions. However these systems do not provide a flexible or convenient method to alter the stock fuel mapping. Like it or not computerised fuel injection will continue to become more commonplace on motorcycles. You may argue that itís unnecessary or on the other hand that itís long overdue, at the end of the day nothing is going to change. The fact is itís here now and here to stay - so get used to it and get on with dealing with it. 

Which brings me to my introduction - the Epicycle EM2 enables you to comprehensively alter the original ECUís injection mapping and is a very effective and flexible engine management system which can be wired into any fuel injection system allowing the user to totally remap the standard ECU. One of the biggest advantages for many users is that it can be used on any motorcycle (or car for that matter) and when it comes time to turn over the bike and upgrade, you just disconnect it and re wire to suit the next bike. 

The $99.00 question is why would you need one if your bike is fitted as standard with itís own management system? That is a very good question and this is why most bikes will benefit. First, the standard system is unable to detect what sort of fuel you use, (which varies from country to country and affects fuel mixtures), your ECU cannot detect normal engine wear over the course of time which affects fuel requirements. It doesnít know the difference between the standard air filter and the after market one not to mention the exhaust youíre about to bolt on. Even some environmental conditions can be a problem. But donít worry itís not all doom and gloom, and letís face it, they do a better job than carburetors and with the EM2 running along side you have a far superior tuning capability than ever before. 

Hereís a basic overview of how it all works. 

The first thing to remember is that the EM2 is connected to the ECU output signals not the input, leaving the ECU to monitor all the sensors and do its job as if nothing has changed. 

The EM2 is connected to each injector, key on power, ignition coil, throttle position and coolant temperature. There are other functions available but these are the main ones required for the system to adjust the fuel map. Weíll assume itís a V twin engine and we have one injector per cylinder. Once all the wiring is done, check that the engine still runs normally, load the software on a computer and connect it to the EM2 via the cable supplied. 

We need to set up the EM2 with all the engine characteristics. The Engine Mode is selected based on the number of cylinders and injectors which in this case we have chosen mode 3, consisting of 2 map tables, the main map for both cylinders and the slave map for cylinder 2. figure1 

The EM2 has to learn the normal cold temperature and normal running temperature. In the drop down menu with ignition turned on we click the learn temp scale button, then start the engine and warm it up to normal operating temperature and turn the ignition off. To accurately measure engine rpm it needs to know which RPM mode to use and in this case we have wired into an ignition coil which fires every 720 crank degrees so, in the drop down menu 720 degrees is selected and while we are at it the max RPM can be set to a pre determined value, for this example we have selected 10,000 rpm. The last 2 functions to set are the warm up ramp, and throttle position needs to be calibrated to read zero degrees when fully closed and 100 degrees when fully open. Unless the wiring is changed or the system is fitted to another bike we should only need to go through this process once. There is one other option available if you have purchased the EM2 pro which has an ignition adjustment feature. We have found on a roadbike with minimal modifications that there is nothing to gain from having it so we are not using this feature. 

We are now ready to trim the fuel map. What is a fuel map? The picture on the top right shows what it looks like on the computer screen. figure 2 

A fuel map is a table of values that tell the EM2 how much fuel to deliver and when to deliver it according to variables such as engine rpm, load/throttle position and engine temperature. On the left side there are values from 0-100% in increments of 10%. These values refer to throttle position which we set up earlier. Across the top are numbers from 500-10,000 rpm. Each of these zones can now be trimmed. Trimming means to change the existing injector pulse as it is sent to the injector. The longer the pulse width the more fuel it delivers. To do this we simply highlight one or more of the corresponding throttle position and rpm boxes and using the page up and down buttons change the value in that area. Each click represents a change of 1% (plus or minus) to the original injector pulse width. As you can see there are a lot of boxes there and yes it does take a bit of time but the result can be well worth all the effort. 

Of course itís all very well changing the numbers, only thing is what do we change it to? This is where there is still some guess work required but it is made a lot easer with the use of a lambda meter supplying live updates of air fuel readings as the changes are made until the required lambda figure is achieved. Once achieved just move to the next corresponding throttle position and rpm box and do it all again. 

Another really good alternative to this, is to apply trims using the Carburetor Simulation controls, found at the bottom of the main screen. This gives you three jet types, Main, Needle and Pilot just as you would see in a carburetor and an overall trim, which will affect the entire map. For those used to tuning carbs itís a very helpful way to achieve a similar result. figure 3

When you change a jet size using the Carburetor Simulation controls, trimming is automatically applied to the map in preset areas. For example a change on the main will affect mostly top end and some midrange just as it would do on a carburetor. To make a change simply highlight one of the corresponding boxes as shown above and use the Plus or Minus buttons or Page Up (+) and Down (-) buttons, each click represents a change of one jet size. 

Once you are happy with the fuel map you can save it on your computer, that way you can make changes to it in the future and save it again as another map. Hereís what your map may look like when itís finished figure 3 

Earlier I mentioned that we had selected engine mode 3, in the pull down menu, consisting of the main map to adjust both cylinders and a slave map to fine tune cylinder no. 2 (rear cyl). The best way to do this is to measure the air fuel, (lambda), off the front cylinder while making adjustments to the main map. As I mentioned this affects both cylinders. 

Once we are happy that the lambda reading is correct it can be moved to measure the rear cylinder. As the rear cylinder runs slightly hotter than the front it is likely that the lambda reading will be different from the front cylinder. Going to the main screen on our computer, (see figure 2), on the top left side there are 3 buttons, clicking the mouse on cylinder 2 brings up the slave map. At this stage it will not have any numbers in it and its purpose is to fine tune the main map. It will only affect the rear cylinder and can be adjusted in the same way as described earlier for the main map. All trims applied to cyl 2 slave map are added or subtracted to the main map trims. 

And thatís it basically. All you need is a laptop computer, a few basic computer skills and before you know it youíll be making some basic changes to your fuel maps. Of course to get the most from it you will need to have the bike put on a Dyno which can read lambda as well as power so that the base maps can be made before you get on the road or race track to fine tune


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