Thundermax FMS

Putting The Tune On Fleeing And Eluding

Article and Photos By: Matt Reel

Originally Published In The May 2019 Issue Of Cycle Source Magazine

If you recall, a few months back I did an article on the engine build I did on Fleeing & Eluding. If not let me catch you up a bit. I had recently pieced together a 2009 Sportster 1200 that was a theft recovery caught in a pursuit (hence the name). After getting it together and riding it a bit, I was trying to decide what to do with it. A Hot Rod kept sticking in my head. I had used Zippers Performance before on Big Twin Engines and was highly impressed with the work they did and the power they made, so I gave them a yell to see what they could do for my Sportster.

Dan and the crew at Zippers, CNC Ported my heads, bored my cylinders .010 over, and built a set of cams. They also supplied adjustable pushrods, a high flow air cleaner, high compression pistons, a tool they designed to clearance the cam chest for the high lift cams, and a lot of advice. With all that together there was no way the stock ECM was going to be able to supply the needs of this engine. Zippers steered me toward ThunderMax. ThunderMax is another company I’ve used before and have always been impressed with. They supplied one of their auto tune ECM’s. The unit is a direct replacement of the stock and just takes a few functions on a laptop to set it up. Here’s how it went on Fleeing & Eluding:

Here is what you get in the package. The ECM, new O2 sensors and sub harness, some zip ties, and not pictured instruction sheet with good color pictures and a software disc for your computer.

I started out by installing the new O2 sensors. If your exhaust is not equipped with sensor bungs a set can be acquired from your local shop. If you’re not 100% confident in your welding skills have a qualified welder install the bungs for you. The slightest air leak around the bung will throw off the readings and the tune.

The plugs on the new O2 sensors are a bit larger than the OEM units. While this isn’t really an issue on bigger bikes, it requires some creativity on the Sportster. ThunderMax actually includes detailed instructions on routing the wires on the Sportster to make hiding things easier.

To tune the ThunderMax, you must connect to it via a USB cable. Due to the location of the ECM on this model Sportster, this is nearly impossible. To remedy this ThunderMax includes a remote wire you add to the harness. Don’t be overwhelmed by taking the ECM plug apart; it’s a pretty simple job.

The ThunderMax can now be plugged into the factory harness and the O2 harness and installed in the factory location.

With everything back together you can now connect to the ThunderMax and start programming. I recommend keeping a battery charger on the battery throughout this.

With all your motorcycle and warranty info typed in you can now find a map that best matches your modifications and load your map. Tip: first find your engine displacement in the list of prewritten maps and right click on it. This will display all the maps for that engine. Next do the same by right clicking your cam grind, exhaust, etc. If you don’t find an exact match something close should get you going, the beauty of auto tune.

Right away the ThunderMax code reader function and gauge display became very useful. After installing my Map, the engine would not fire. A quick review of everything found a bad engine head temp sensor. Notice 40 degrees on the gauge. While the engine had not yet been fired it was a hot day. The sensor had the ECM turning the fuel way up for a cold start. That was quickly fixed, and the engine was running smoothly.

I was lucky enough to be able to take my bike to Zippers Performance for some fine tuning. The kit they put together for me had some changes from their standard Super Hammer kit, and they wanted to build a map for it there.

Starting out with a Super Hammer map Bobby tuned the fuel map in RPM increments until it was dialed in perfect. While this was done on a dyno, the same tune could be have been reached by simply riding the bike and running the auto tune function every few rides.

So here it is. 97 hp and 82 ft/lb. of torque out of a 1200 cc engine. Remember it was only bored .010, so no big displacement gain. The engine also only had a couple of hundred miles on it and was still seating the rings. Fully broken in with some timing changes it should be in the triple digits.

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