1. Light 1 side of grill, heating to 225° to 250°; leave other side unlit. Close grill lid, and maintain temperature 15 to 20 minutes.
2. Remove giblets and neck from turkey; pat turkey dry. Sprinkle salt and pepper over skin and inside turkey cavity; place thyme sprigs and sage sprigs inside cavity. Tie ends of legs together with string, and tuck wing tips under; place turkey, breast side up, in pan.
3. Stir together softened butter, chopped sage, and chopped thyme. Shape butter mixture into a 2-inch ball; press ball firmly onto top of turkey breast. Cover roasting pan with a double layer of heavy-duty aluminum foil, sealing edges tightly. Cut a 2- x 1-inch hole in foil directly over butter.
4. Place wood chips directly on hot coals. Place pan with turkey on unlit side of grill; cover with grill lid.
5. Smoke turkey, maintaining temperature inside grill between 225° and 250°, for 6 to 7 hours or until a meat thermometer inserted in thickest portion of turkey thigh registers 165° to 170°. Peel back foil from turkey during last 1 to 1 1/2 hours of cooking time.
6. Remove turkey from grill; let stand 15 minutes before carving.