Set up a grill for indirect grilling, with the coals on one side, and heat to 425°. Meanwhile, in a medium skillet set on the grill or the stove, cook the bacon over moderate heat, turning once, until crisp, about 6 minutes. Drain on paper towels and crumble.
Line a 12-cup muffin tin with paper liners. In a large bowl, whisk the flour, cornmeal, sugar, baking powder, salt, baking soda, black pepper and cayenne. Stir in the corn, scallions and crumbled bacon.
In a medium bowl, whisk the eggs with the sour cream and melted butter. Fold the wet ingredients into the dry until just blended. Pour the batter into the muffin cups.
Place the muffin tin on the grate opposite the coals, cover the grill and bake for 20 minutes, or until a toothpick inserted in the center comes out with only a few crumbs attached. Serve slightly cooled.