Drain pineapple juice into a small bowl; add teriyaki sauce. Place 3 tablespoons in a resealable plastic bag. Add pineapple slices; toss to coat and set aside. , Shape beef into four patties; place in an 8-in. square baking dish. Pour the remaining teriyaki sauce mixture over patties; marinate for 5-10 minutes, turning once. , Remove burger patties from marinade; discard marinade. Grill, covered, over medium heat or broil 4 in. from the heat for 6-9 minutes on each side or until a thermometer reads 160° and juices run clear. Meanwhile, in a small skillet, saute onion in butter until tender, about 5 minutes; set aside. , Remove pineapple slices from marinade; discard marinade. Place pineapple on grill or under broiler to heat through. Layer bottom buns with lettuce and onion. Top with burgers, cheese, pineapple and bacon. Replace tops.