Effect of the Induction Pipe in a Crankcase-Scavenged Two-Cycle Engine

Abstract

The performance of a two-cycle engine is fairly well improved by the effects of the inlet and exhaust systems. The flow areas of the inlet and exhaust systems of the usual engine are not always suitable to make full use of the effects of these systems. The present authors have experimentally investigated the inlet system of a crankcase-scavenged two-cycle engine, which brings a most remarkable improvement to the delivery ratio. It has been confirmed that the delivery ratio increased by the effect of the induction pipe reaches a maximum at the period of inlet port opening, which is longer than the usual. Further they have examined the flow resistance of the carburetter and the air cleaner by replacing them with an orifice, and found out that the effect of the induction pipe is entirely nullified at the area ratio of the orifice to the induction pipe below 0.3∼0.4.