It doesn't appear as though Starkiller had any robotic parts after his reconstruction aboard the Empirical. All his limbs and such seemed fully organic. I don't see why he'd need them. He didn't have any limbs cut off or anything. All Vader did was bash him around and throw him out a window into space. When Vader rebuilt him, all he'd really have to do would be to heal up the wound Marek suffered when he was impaled with that lightsaber (which wouldn't require any cybernetic reconstruction), and make sure all his organs and such were working properly.