Summary
Summary will be a bit long. I’m usually the skeptic. It’s fun to be this pleased and impressed by a new product though.
This bike ran great before the EMS installation. It runs better now. It had a good tune before. It’s been improved. EMS has made the bike smoother with noticeably sharper throttle response. It’s also much better behaved in cold weather. But all that’s not the half of it.
This bike did have a good tune. The bike ran great, pulled hard and pulled early. It reported 120 hp and 120 ft pds of torque and got 35 mpg while doing so. Not bad. Many of you have ridden it. I loved the way it ran. So no real performance gains were expected.

The goal here, and promise of the EMS product, is that starting from then building on the admittedly significant capabilities of the stock ECM that a more stable, more capable, more immediately adaptive and more efficient engine management platform is capable. The stock maps are restrictive. For environmental and other reasons. The stock hardware isn’t fully exercised or used most efficiently. Cracking the code on the stock ECM, building a map whose first goal is making the bike run well and combining that map with hardware and software additions whose purposes are to more fully and efficiently utilize the map and onboard systems suggests potential real improvement for engine management. That suite of improvement is what got my interest.
Having said that no real performance gains were expected; some were had anyway. In a few different ways both subtle and large. The bike is a much smoother low speed performer now. The dyno tuned map appears in comparison to have been better optimized for time above 2800-3000 RPM. It wasn’t bad before. It’s just significantly more responsive now at lower and mid-range RPMs that are produced at lower throttle position settings (TPS).
The bike’s torque curve comes in sooner now. That’s always good for a heavy bike. The pull is also smoother between 2000 and 3200. Before there was a noticeable spot where the bike seemed to catch its breath about 2800. No longer. It starts pulling now and just keeps going. Evenly, smoothly and overall more strongly than it did before.
The bike initially starts and runs much better in cool temps. Previously it felt like a carb’d bike when started at temps of 35 or so and below. Now it’s smooth from moment one in temps that have been as low as 25.
Now the real kicker. There is real performance improvement, an overall smoother running engine with sharper throttle response and an overall better riding experience out of a bike that already ran great to begin with. And I went from 35 mpg to 45 mpg in the process. So it is doing whatever it is doing much more efficiently.
A cool difference in the bike now is that with the simple Dayton Twin Tec scan tool that tool can be setup for use with wide band sensors and AFR monitoring. Using it here on a “dumb” old 2005 bike that was never intended to have this capability the Twin Tec scanner plugged right in to the bike’s stock data port and now gives live AFR readings. Readings that can be logged and studied for your amusement or other use.
It was interesting to watch the EMS system “learn” the bike during its first minutes of idling after first start up. Reviewing data logs over about 450 miles so far have further shown at least the basics of the adaptability the bike has now that it never had (couldn’t have had) before.
Engine management settings danced around for the first 20 miles or so the bike was ridden after install. After that nearly zero new movement. That is not to say AFR and other engine management settings are always static now. Just that your “tune” is done after about 20 miles of riding. Just riding.
Now rather than a straight 13.5:1 AFR, for example, you can see a given RPM at a TPS relative to a highway cruise speed be higher than the same RPM at a TPS that would be relative to accelerating to pass a truck or putt-putting through in-town traffic. Its programming is now smart enough to vary and adapt to need and load And it does this more quickly, efficiently and correctly than I’ve ever seen engine management on any other Harley system do this before.
It really was cool to review the data logs. The adaptive read of its own history and repopulation of the VE tables at each ride real time is probably what will avoid the “wandering” tune that some Twin Tec and Thundermax module users have experienced. This gets beyond my homework and understanding of the system. But it’s an ability of the EMS system that helps our experience each and every ride.