In this study; a four-stroke, air-cooled, spark-ignition engine was used. It’s aimed to improve the performance and emissions by renewing the existing ignition and fuel system of the engine in a way that can be controlled via computer. Classical ignition system was modified with an electronic ignition system and a computer-controlled system was established by using an injector instead of the carburetor. Gasoline and bioethanol fuels were compared with the original and updated version of the engine by conducting various experiments. In these experiments, engine power and torque, specific fuel consumption, thermal efficiency, exhaust emissions and combustion analysis results were examined. When the results obtained are evaluated; with the use of electronically controlled fuel and ignition system in engine torque and power, an increase of 11.58% in maximum torque obtained from gasoline and an increase of 14.4% in average power was observed compared to the standard system. Specific fuel consumption decreased by 18.32% for gasoline and 26.95% for bioethanol at full load. At full load, thermal efficiency was 22.43% for gasoline, 36.9% for bioeth-anol and in-cylinder max. pressure was a 4% increase for gasoline and an 8% in-crease for bioethanol. In the emission values, at full load, the CO value decreased by 6.2% for gasoline, 20% for bioethanol and HC value decreased by 3.8% for gasoline and 7.5% for bioethanol. CO2, NOx and O2 values increased by 4.1%, 14.9%, 0.7% for gasoline and 0.7%, 5.6%, 0.4% for bioethanol.