Patent ID: 6889637

Claim:
A two-cycle engine having a cylinder in which is formed a combustion chamber that is delimited by a reciprocating piston which, via a connecting rod, drives a crank shaft that is rotatably mounted in a crank case, wherein an inlet opens into said crankcase, wherein said inlet communicates with an intake duct section of a carburetor via which a fuel/air mixture is to be drawn into said crankcase, wherein a cross-sectional area of said intake duct section is variable via a butterfly valve that during idling of said engine is disposed approximately transverse to a longitudinal central axis of said intake duct section and during full throttle is disposed approximately parallel to said longitudinal central axis, wherein at least one transfer channel is formed in said cylinder and connects said crankcase with said combustion chamber, wherein at an end facing a cylinder head of said cylinder, said at least one transfer channel opens into said combustion chamber via a transfer port that is controlled by said piston and that is open in a lower position of said piston and is closed in an upper position of said piston, wherein an end of said at least one transfer channel that faces said crankcase is open in both said upper and lower positions of said piston, wherein an air duct is provided that via a controllable connection is in communication with said at least one transfer channel in a vicinity of said end of the latter that faces said cylinder head in order, during a load state of said engine, to supply essentially fuel-free air to said at least one transfer channel, and wherein an outlet is provided on said cylinder for conveying exhaust gas away from said combustion chamber, said engine further comprising: a dividing wall that extends in a direction of flow of air through said carburetor and divides an intake duct of said carburetor such that one duct portion, which is provided with fuel supply means, forms said intake duct section, and another duct portion forms said air duct, wherein said dividing wall extends essentially over an entire length of said intake duct from one end face of a housing of said carburetor to another end face thereof, wherein in a pivot region of said butterfly valve said dividing wall is provided with a connecting aperture that in a full throttle state of said engine is essentially closed by a completely open butterfly valve such that in said full throttle state said air duct and said intake duct section are separated from one another.