Aprilia Futura Primary Can Deconstruction

by Duane Hazen

Well, I've been waiting for someone to tell us all that they finally got the gumption to open up the under bike can........ got tired of waiting any longer. So, I pulled the "primary muffler" off and lopped it open. Well, I'm happy to report that it was a task worth performing. Not only did it improve sound quality by removing the baffle canister, but this bike now pulls much harder than before through the entire rpm range right up to 10K.

Now I am forced to manage my acceleration in 1st gear to keep the front end near the ground, and when I hit second gear, the front end still manages to lift. This was never the case with the RST before the mods. In stock form the bike would power wheelie in 1st at about 7 k rpm,if I kept the throttle wide open. Now it happens almost too easily, and I don't need to hold the throttle wide open to make it happen. A good feeling.

I'm running, deristricted air box, Evo filter, Stain tunes, RST staintune map using the Tuneedit software. I'm scheduling dyno time next week.... will advise.

I still like the idea of eliminating the primary muffler, the engine would breath even better. With the baffling canister removed, the primary canister is nothing but a large collection box for exhasut gases...two tubes going in and two going out to the rear cans.

The sound of this bike will never be as deep as a Ducati, or a RC 51( which you may have seen me comment to in the past as I have one with a full Micron system that has a great tone) .... I've slowly come to accept this, and the final determining factor was after I decided to start the bike without the primary can connected. Totally Briggs and Stratton. Perhaps larger diameter pipes that run from the engine heads to the slip ons would make a difference. Anyhow, as for the resulting sound "quality" achieved after removing the baffle, I would comment that the tone has deepened, and the amplitude is a tad higher, yep, meaning it's a little louder. Once the baffle is removed, the primary can is just a big metal box that has two inputs and two outputs, with no restrictions in between. The performance gain is what I found to be more surprising. Again, I haven't dyno'd the bike yet, but having just returned from a 4 day trip to TN & NC to ride Deals Gap, the feel of the bike before removing the baffle was very fresh in my mind. ( By the way, I was riding with my buddy on his RC51 we passed a pair of riders 1 -BMW and 1 - red Futura on Rte 311 on the W VA and Virginia border.....was that any of your guys?) Anyhow, a couple days after returning to Cleveland, I removed the baffle, and immediately, I noticed increased power throughout the rev range on my test run. So my internal dyno approves.

I like big booming sound from big twins, admittedly, so my concept of a great sounding bike will probably never be met with the Futura motor..... but a hard pulling motor is also important as I need to keep my buddy on his RC51 in check..... glad I pulled the baffle.

By the way, if you're thinking your afraid of leaning the bike out too much, I wouldn't be too concerned. True I have the tune that Wayne Mc Donald generated in my ECU. Per Wayne, his tune is leaner than the original Aprilia tune, and my bike still runs rich. He said it would. Evidence of this is in the plug readings, and carbon deposits on the slip ons...also, since I pulled the baffle, I can hear an occassional backfire after running the bike up to 8-9 k and closing the throttle....still have some unburned fuel in the exhaust. I'll probably be leaning it out a bit more.

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