What is the wire under air box cover

[Caffinated]

2004 XB12s. Under the airbox cover (faux gas tank) there’s a wire harness that leads to a connector at the top of the airbox into the foam under the plastics. There’s an empty space where possibly a computer or ECM or other black box once lived. My bike is running fine. This bike is new to me and my first Buell. I know this bike has mods. No problem here, I’m just curious what used to live in there.

 

[Heavy18]

That is where the controller for the OEM muffler valve is installed. I'm assuming you have an aftermarket muffler so the controller was removed.

The OEM muffler had two different exhaust routes inside and could switch between them with a servo driven by the missing controller. The controller would change the routes based on your RPMs to provide the best performance by adjusting the length of your exhaust.

I've seen it said that when you go to an aftermarket exhaust you lose a little bit of low end torque (IIRC). I've also seen it said that you regain that loss with the proper tune for an aftermarket exhaust. The Buell race team ran a straight pipe exhaust with a tune so I think it is safe to say you can regain the loss with a tune - or maybe they just always were above the impacted RPM zone...

When I installed my aftermarket exhaust and tune my seat-of-the-pants dyno felt a performance increase starting mid-RPM with no loss on the bottom end, but maybe I was just drunk with the new, beautiful sound my bike made...