Moto400 is a little ways north of the outlet mall, just ½ mile north of the intersection at Ga Hwy 53 on Ga 400.
The mapping services that google etc. use are still a little behind so not all the roads are shown, but here they are:
If you're coming from the south, either
- turn left at 53, immediately turn right and wander the roads back to the movie theater then hang a right down the hill, or
- continue on 400 past the shop, take the next left then left again