V-twin Tech: Cooler and better running with Cobra’s Fi2000R EFI Tuner
September 25, 2007
Filed under Uncategorized
Harleys have run too lean for about a quarter-century with emission standards to blame. Never mind that the General Accounting Office (GAO) has told congress that motorcycles are an insignificant source of pollution; they are still regulated and stifled just the same. By forcing very lean air/fuel (AF) mixtures and regulating noise-emission levels, those stifling regulations have greatly robbed engine performance. Now, the latest round of restrictions has Harley owners concerned and struggling to find a way to avoid critically high cylinder-head temperatures caused by excessively lean AF mixtures.
The Motor Company has done an excellent job of adapting its V-twin engine designs to comply with emission requirements as those requirements have been tightened over the years. I congratulate them for having done so.
However, I find it unacceptable that under emission requirement standards my stock 2007 Harley-Davidson Twin Cam 96 engine runs cylinder-head temperatures higher than an XR750 dirttrack motor at the end of a long straight. Four hundred degrees is too much; 300-325 would be better.
Since all Harleys affected by these latest and most extreme restrictions are fuel injected, it is the EFI system we must alter to drop temperatures and improve performance. Harley’s closed-loop EFI system is sophisticated, capable, and highly developed, but it is deliberately difficult to alter. Because of federal oversight, Harley does not dare make it easy. Accordingly, we, the riders, are left with the task of altering the signals from the stock ECM (electronic control module) in order to richen AF mixtures and increase engine performance. A number of companies, including Daytona TwinTec, Dynojet, Terry Components and Vance & Hines, make “break out” boxes that allow such alterations. The Cobra Fi2000R EFI Tuner we are testing is an example.
Cobra’s Fi2000R EFI tuner intercepts the signals from the oxygen sensors to the stock ECM. It also intercepts the signals from the ECM to the injectors. Then, with this information from the sensors, it alters the signals to the injectors telling them to increase the length of time they are open. Longer open times increase the amount of fuel injected thus richening the AF mixture.
The three dials on the Fi2000R control module determine the amount of time the injectors stay open. More specifically, the position of each of the three dials tells the module how much to increase the AF mixtures within the rpm/throttle range of each of the dials. Correct positioning of the dials is initially set from recommendations in the instructions. Field-testing can then be used to refine those settings (see V-Tech Telephone-Pole Tuning on page 90 in this issue).
Installation of the Cobra Fi2000R could hardly be easier. The process is completely reversible as no permanent alterations are made to the bike. Also, there is no outward sign of the installation when finished—you actually have to remove the seat and expose the control module to even know that there is a Cobra on board.
The installation and tuning instructions that ship with the Fi2000R are short, accurate and complete. They are available for download from the Cobra website if you’d like to read them (www.Fi2000R.com).
Cobra’s website claims an installation time of 30 minutes. I have no doubt that is accurate—if you’ve done the job before. Editor Buzzelli and I took an hour-and-a-half to complete ours. However, we were taking pictures as we went, and also generally getting in each other’s way. An hour for a first-timer seems like a reasonable installation time to me.
I strongly recommend that you browse around the Fi2000R website. It is filled with information you’ll find interesting. The site discusses fuel injection and AF mixtures as they apply to Harleys. The overview page is particularly well written and useful. The Fi2000R Adjustments page relates the adjustment dials to carburetor tuning components and their comparative effects. The FAQ page is informative and clear. I would like to see these pages incorporated into the printed instructions. Cobra might be surprised to learn just how many Harley folks deliberately stay away from the Internet.
All our tests up to this point have incorporated trials done on Barnett Tool & Engineering’s Dynojet 150. In our first test we investigated how adding and subtracting a K&N air cleaner and a set of Screamin’ Eagle mufflers affected engine performance (April 2007). Our second test installed a SuperTrapp 2:1 exhaust system with 18 discs (June 2007). At the end of test two we posed a question wondering whether or not our stock EFI system was the factor limiting our engine performance. In this test, we are going to explore the effects of the Cobra Fi2000R on our Twin Cam 96 engine to find out.
Testing and Tuning
After installation, the Cobra module’s dials were adjusted to the recommended positions. We then made several full-throttle runs and recorded the power. We found no significant gain over what we had achieved with the large K&N air cleaner and the 18-disc SuperTrapp 2:1 system. We ran out of time that day and did not have a chance to explore the Fi2000R’s range of adjustments so we could not draw any conclusions.
We then rode our Dyna on the street for a week or so. Throttle operation was more crisp and responsive mid-rpm, but there were no important gains in peak power. The engine seemed to be too lean.
We returned to Barnett to make test runs and fiddle with the dial positions. Ah! Much better! After some dial-position refinements we had gained more power by adjusting the Fi2000R than we did by installing both the air cleaner and the exhaust system in test one. Without an EFI tuner to richen the AF mixtures, the engine in test one had been so lean that it could not develop power significantly greater than stock even with the addition of a proven free-flowing air cleaner and exhaust system. Our initial run with the Fi2000R hadn’t been fruitful because the recommended dial settings had simply been too lean. Once again I learned that there is nothing quite like actual testing.
Out of the shop and back on the road, our Dyna Twin Cam 96 was a different motorcycle. Throttle response was seemingly instantaneous. Acceleration was noticeably quicker at all throttle settings, especially in the 20-60 percent range that the great majority of us normally use.
If I had been working with a carburetor and a separate ignition system, the extremely lean mixtures would have been quite apparent. There might have been popping in the intake manifold during acceleration, popping in the exhaust during the overrun, flat acceleration and, very likely, some detonation under load. The sophistication of the stock closed-loop system fitted to this engine hid or compensated for the leanness like no carburetor and separate ignition system ever could.
A subsequent mileage check revealed that our final dyno adjustments with the Cobra were too rich for best efficiency. This is something I expected and consider normal after initial tuning. We got 40.6 mpg, which isn’t all that bad, but it should be closer to 48. As I write this we are in the midst of leaning the Fi2000R’s middle dial position to find the best compromise of power and mileage.
Cobra’s Fi2000R does exactly what it was designed to do: It adjusts the AF ratios of the stock Harley EFI system to improve performance and compensate for engine system alterations. We did not detect any performance or operation issues.
It is well made and easy to install. So easy, in fact, even two bumbling journalists could manage! The wiring harness is wrapped and sealed against abrasion and water intrusion. The connectors are equal in quality to the OEM parts. The control module’s plastic is thick and tough. But the dial cover latches are a bit fragile, so treat them kindly. I didn’t, and I broke one. A bit of electrical tape and all was fine.
Most importantly, the Fi2000R is easy to adjust; very easy to adjust when compared to carburetors. All you need to tune the Cobra is a big screwdriver to remove the seat and a small one to turn the dials.
Getting the adjustments right requires some practice and patience but no special knowledge. The information on Cobra’s website and in my V-Tech column should be enough to help you understand what the Cobra Fi2000R does and how to get the most out of it. You can apply this to the other break-out boxes I mentioned earlier as well.
Now our Dyna not only runs better, with more power, it also runs cool. Cylinder-head temperatures are down around 300 degrees and I am no longer concerned about premature wear or meltdown on a mountain pass.