Grease tube pan. In a bowl stir together the flour,baking powder,salt and baking soda. set aside.
In a large bowl beat butter about 30 seconds.Add sugar and beat until fluffy. Add eggs one at a time,beating well after each one.
In another bowl mash the bananas with a potato masher and combine with ,sour cream ,milk oil and vanilla
Alternately add flour mixture and banana mixture to butter mixture,beating on low speed after each addition just until combined.
Stir strawberry preserves into 1 cup of the batter. Also stir cocoa powder mixed with 2 tablespoons of sugar into another 1 cup of the batter.
Spoon half the remaining plain batter into greased tube pan.Spoon strawberry batter over the plain batter. On top of strawberry batter spoon with remaining plain batter.And last spoon on the chocolate batter.(mine was thicker so I spread it around in the middle of the plain batter.)
Bake at 350 degrees oven for 55 to 65 minutes. After it has cooled ice cake to your taste.You can also leave it plain or use sift powder sugar on cake.