Abstract: A muffler device of a motorcycle including a muffler body for silencing the noise of exhausts of an engine located below the engine and connected to exhaust pipes which in turn are each connected to one of cylinders of the engine. Discharge pipes are connected to the muffler body to discharge the exhausts from the muffler body rearwardly of a motorcycle body.

Abstract: A sprocket for a motorcycle in which noise due to chain-sprocket intermeshing is reduced. A pair of resilient vibration reducing members are provided, one on each side of a metal sprocket body. The circumferential edges of the vibration reducing members are either curved or tapered to maintain contact with the motorcycle drive chain over a wide range of load conditions.

Abstract: A method of stabilizing operation of a hybrid spark chamber is disclosed. The method is applied to a self-triggering hybrid spark chamber of the gas-flow type including a spark chamber portion and a proportional chamber portion, and utilizes a high speed discharge circuit for the proportional chamber portion, the high speed discharge circuit being so constructed that upon generation of a precedent spark in the spark chamber portion by electrons produced by radiation and multipled in the proportional chamber portion the discharge circuit is simultaneously operated in response to the spark so as to rapidly lower an electric field intensity of the proportional chamber portion, thereby preventing the generation in the proportional chamber of any induced spark.

Abstract: A muffler for a motorcycle engine including a hollow, frustoconical muffler body, a hollow sound-absorbing member snugly fitted in the muffler body and maintained in intimate contact with the inner surface thereof, and a keep member for securing the sound-absorbing member in place. The sound-absorbing member is inserted in the muffler body and the keep member is inserted therein. The keep member is pressed into the hollow sound-absorbing member by a muffler core as the latter is inserted therein, to force the sound-absorbing member against the inner surface of the muffler body in intimate contact therewith. The muffler core includes a baffle tube extending axially of the muffler body, and a plurality of discal baffle plates secured to the baffle tube to define a plurality of chambers in the muffler body when fitted therein.