A cup holder? I think we might be talking about different spots here. There is a vertical black panel that would be close to the right handlebar at full left lock. At the base of this panel is a horizontal black panel that has the battery beneath it. Behind the vertical panel is a myriad of things: the bolts for the mirror mounts, the small tubular frame that the front cowling attaches to, and numerous electrical doo-dads (relays, wiring, etc.). I would think that you could mount a cup holder here, although the cup would be hard to reach when going straight. I think others have used handlebar mounted cup holders.
BTW, these panels are not hard to remove for investigation. In fact once you have had them off once its damn simple!