Abstract: An exhaust gas muffler comprises a double-walled casing having an inlet end receiving a stream of the exhaust gas and an outlet end for the exhaust gas, the outlet end comprising an outer tube surrounding a perforated inner tube spaced therefrom, and the tubes defining therebetween a perforation resonator chamber succeeded by a whistling sound resonator. The casing includes an outer wall and a corrugated inner wall defining a gap with the outer wall. A heat-resistant and sound-damping intermediate layer is arranged in the gap between the inner and outer walls and braces the inner wall against the outer wall. Transverse partitions divide the casing into a plurality of chambers between the inlet and outlet ends, and tubes connect the chambers and reverse the exhaust gas stream at least twice between the inlet and outlet ends.

Abstract: An intake muffler, which is particularly intended for use in two-stroke-cycle internal combustion engines, comprises a stiff housing, in which a partition defines two chambers. An inlet tube extends into the larger first chambr. At least two communicating tubes extend through the partiton. The second chamber communicates with a tubular outlet port. In order to ensure an effective damping of sound even in conjunction with a high engine power, the inlet tube consists of a diffuser, which is divided into two or more passages, and the tubes through which the two chambers communicate with each other differ in diameter and/or in length.

Abstract: A two-stroke-cycle internal combustion engine designed for crankcase scavenging has an exhaust passage, which extends from an exhaust window in the cylinder wall and which contains a control member, which is adjustable in the direction of travel of the piston to adjust the flow area of the exhaust window in dependence on one or more operational parameters of the internal combustion engine, in particular, in dependence on its speed. In order to minimize the scavenging losses and to permit the engine to combust even very lean mixtures while having a good drivability, the control member conforms to the flow lines in the exhaust passage and constitutes that edge of the exhaust window which is nearer to the crankshaft and said control member is movable to adjust said edge.