Peel yams and cut in one-inch pieces. Place yams in cold water until all yams are peeled and cut. Drain yams. Place cut yams in deep baking dish. Add sugar, pineapple juice, orange juice, and water. Sprinkle ground cinnamon over top of yams. Cover yams and bake in 400 degree preheated oven for approximately 40-50 minutes or until yams are fork-tender.