In a large skillet over medium heat, fry the ground beef, bacon and onion together until ground beef is no longer pink. Drain fat.
In a large mixing bowl, combine the kidney beans, baked beans with pork and butter beans. Stir in the ketchup, white vinegar, dry mustard, brown sugar and cook beef mixture. Mix thoroughly, adding salt and pepper to taste.
Pour the bean and meat mixture into a 9x13 inch baking dish. Bake in preheated oven for 30 to 40 minutes.