1. Preheat oven to 350 degrees F. Line 18 muffin cups with paper liners. Combine flour, baking soda, cinnamon, baking powder, and salt in a medium bowl; whisk until blended. In a separate bowl, beat eggs and sugar with a wooden spoon. Add oil and orange juice, then combine with flour mixture. Fold in carrots.
2. Divide batter among prepared liners. Bake 18 to 22 minutes, or until a toothpick inserted into center comes out clean. Transfer to a wire rack and let cool completely.