In a large bowl, dissolve yeast in warm water. Add the bread flour, oil, honey, salt and 4 cups whole wheat flour. Beat until smooth. Stir in sunflower kernels and enough remaining flour to form a firm dough., Turn onto a floured surface; knead until smooth and elastic, 6-8 minutes. Place in a greased bowl, turning once to grease the top. Cover and let rise in a warm place until doubled, about 1 hour., Punch dough down; divide into 3 portions. Shape into loaves; place in 3 greased 8x4-in. loaf pans. Cover and let rise until doubled, about 30 minutes., Bake at 350° until golden brown, 35-40 minutes. Brush with melted butter. Remove from pans to wire racks to cool. Freeze option: Securely wrap and freeze cooled loaves in foil, and place in resealable plastic freezer bags. To use, thaw at room temperature.