Inconjunction with the test stand and the load unit, the simple four-stroke petrol engine is highly suitable for use in teaching the fundamentals of engine functioning and measurement. The engine used here is an air-cooled single-cylinder four-stroke petrol engine with external carburation. The engine is started by an electric motor mounted in the unit. The air cooling is effected by a flywheel fan. The load unit is coupled by way of a pulley on the drive shaft. The engine includes a sensor to measure the exhaust gas temperature. The sensor, ignition cut-off as well as air and fuel supply are connected to the test stand.