Lightly grease 18 muffin cups or line with paper liners; set aside. Preheat oven to 375F. In a large bowl, stir together flour, baking powder, baking soda, salt and sugar. Stir in coconut. Make a well in center; set aside. In a medium bowl beat eggs. Stir in sourdough starter, oil, bananas, orange juice and orange peel. Pour into well in flour mixture. Stir with a fork until dry ingredients are just moistened. Fill prepared muffin cups 2/3 to 3/4 full with batter. Bake in preheated oven 25 to 30 minutes or until golden brown. Remove from muffin cups. Serve hot. Makes 16 to 18 muffins.