This paper deals with a successful attempt to employ the exhaust gases of a two-stroke cycle gasoline engine as an energy source to operate an after burner and a Stirling engine, and to clean the exhaust gases by a catalyzer. By means of a rotary valve and the exhaust pipe sections, the exhaust gases could separated into a high concentration of fresh gas and a high concentration of combustion gas. The former gas was burned by a burner, and then used to heat a Stirling engine. The latter gas was disposed of by an oxidation catalyzer. The investigation revealed the enthalpy and exergy flows of a two-stroke cycle gasoline engine, a burner, a catalyzer and a Stirling engine, and then the emission gases (HC, CO, NO) were disposed of by the burner and catalyzer. The investigative analysis shows a method of successfully transferring the energy available in the exhaust gases for the combustion of a burner and the operation of a Stirling engine, a burner and a catalyzer.