Injini yakunja ndi njira yothamangitsira yomwe imayikidwa kunja kwa boti. Nthawi zambiri imakhala ndi injini, gearbox ndi propeller, zonse zimayikidwa mugawo limodzi. Ma motors awa adapangidwa kuti achotsedwe mosavuta ndikumangiriridwa ku transom ya bwato, kulola kuyika ndi kukonza molunjika. Ma injini a Outboard amabwera mosiyanasiyana kukula kwake komanso mphamvu zake kuti zigwirizane ndi kukula kwake komanso kagwiritsidwe ntchito kake.