The cover for the airbox on this Honda generator hinges open to the left, but the frame rail is directly in front. The airbox is also bolted to the engine from inside (behind the filter).
I've throughly looked over this and there is no way to open that airbox unless you unbolt the engine from the frame, or perhaps modify the lid hinges with a saw so it doesn't have to swing as far to come off.
I had three scooters that I used for my restaurant delivery. All 3 were piaggio but one of them was from a Chinese joint venture with piaggio. I'm going to assume that Piaggio made the engine and the Chinese the frame, body and assembly. This scooter from hell has the spark plug blocked by a strut. You need to drop the engine to replace. The other two have extra nice access, with cutouts in the plastic parts for easy access, etc.