Drain pineapple; combine pineapple juice with wine, lemon juice, oil, honey, and garlic.
Cut the yams into 2-inch chunks and the bananas in 1-inch thick slices. Add yams, bananas, and onions to marinade. Let stand in refrigerator overnight, or for at least 2 hours at room temperature. Turn several times; drain, reserving marinade.
Alternately thread pineapple, yam, banana, and an onion, then repeat, ending with a cube of pineapple, on 12 skewers. Grill 5 inches above heat 8 to 10 minutes, turning skewers to brown all sides, brushing with marinade as you turn. Serves 12.