Preheat oven to 350 degrees. Butter a bundt pan. In a large bowl, cream together butter and sugar. Beat in eggs, one at a time until fluffy. Beat in vanilla, maple extract, yams, sour cream, orange juice and rind until creamy and smooth.
    In separate bowl, stir together flour, baking powder, baking soda, cinnamon and salt until combined. Gradually blend this into the creamed mixture until uniform consistency. Stir in raisins.
    Combine all streusel ingredients in a small bowl. Spoon 1/2 of batter into prepared bundt pan, smoothing top to make even layer. Sprinkle on half of streusel mixture. Repeat this procedure, ending with final layer of streusel.
    Bake cake for 1 hour and 10 minutes or until toothpick inserted comes out clean. Cool for about 30 minutes before removing from pan.