It is of current importance to reach carbon neutrality in various transport sectors as soon as possible, with regard to the fact that transport, characterized by the utilization of piston combustion engines, is one of the main polluters in urban agglomerations. Piston combustion engine pollution also significantly influences the quality of the living environment and human health. The application of biofuels containing bioethanol or biodiesel essentially contributes to the reduction of air pollution caused by exhaust gases, also taking into consideration the renewability of these fuels. Therefore, the modification of spark ignited engines is necessary for the correct operation of ethanol combustion and to remove risks during operation and combustion, mainly the possibility of detonation combustion. To date, there has been a gradual development of engines intended for the combustion of the fuel mixture gasoline–bioethanol, mainly the fuel E85. This fuel mixture contains 85% ethanol and 15% gasoline. This paper is focused on construction modifications of a specific combustion engine, which operates with a two-stroke working cycle, which is predominantly intended for installation in category L motor-sport vehicles and kart race vehicles. A new construction solution specifically for this engine was developed and consequently patented. The results obtained while testing this engine in real racing conditions confirmed the correctness and purposefulness of the proposed engine concept
