Reduction of Exhaust Smoke & Carbon Deposit at Exhaust Port in Two-Stroke Gasoline Engines

This paper deals with the generation mechanism of exhaust port clogging from carbon deposit and visible exhaust smoke as well as the method to reduce them. Consequently, it was found that the selection of appropriate exhaust port shape and the reduction of distillate of high boiling point mineral oil in the engine oil were effective to reduce exhaust port clogging from carbon deposit. While, increased exhaust gas temperature at the rear outlet end of the muffler and reduced reaction energy (measured by D.S.C.-a method for thermal analysis) in the engine oil were found to be effective to reduce visible exhaust smoke. It is desired that not only engine and related components but also oil should be improved from now on.