Originally Posted by markjenn
A few of the newer non-single bikes with an emphasis on efficiency do use a single TB (the NC700X comes immediately to mind) but I think it is uncommon.
The S1000RR definitely has individual TB's, but I've never seen anything definitive about why they don't require any synchronization. It is definitely drive-by-wire, so each TB is controlled by a servo but I would still think there would need to be some calibration to make sure all the servos and position sensors are properly synchronized. It may be one of those things where BMW feels that once set at the factory, it should never go out of synchronization. I certainly know of many bikes that have servo TB's and still have conventional air bleed screws and require periodic synchronization by balancing manifold vacuum with the bleed screws. Short of having a MP sensor that measures vacuum in each inlet tract, I don't know of any way for the system to adjust itself based on running conditions.
I read something about the new GS having something that measures vacuum and then makes adjustments constantly.