In a small bowl, combine the sambal with the mayonnaise and ketchup and mix well.
Light a grill or preheat a grill pan. Grill the bacon over moderate heat, turning, until golden and crisp, about 5 minutes total. Drain on paper towels.
Form the beef into eight 1/4-inch-thick burgers and season with salt. Grill over high heat, turning, until browned, 1 minute per side. Make 4 stacks of 2 burgers each on the grill and spoon 1 tablespoon of the sambal mayo over each stack. Top with the cheese, cover and grill over high heat just until the cheese is melted, about 1 minute.
Spread the remaining sambal mayo on the bottom buns. Top with the burgers, bacon and kimchi, close and serve.