Cut the sweet potatoes into even 1-inch cubes. Toss them with the bacon, pecans, maple syrup, chili powder, salt, cinnamon, and cayenne in a bowl. Spread in a single layer on the prepared baking sheets.
Roast for 20 minutes. Stir and continue roasting for 15 minutes, or until tender. Turn the oven to broil and brown the potatoes for an additional 5 minutes. Watch the nuts closely and pull the baking sheets out early if they begin to burn. Serve hot.