Two-stroke engine with variable scavenging port

A two-stroke engine including a piston slidably received in a cylinder bore defined in a cylinder block, a combustion chamber being defined by the cylinder bore and the piston, comprising:

• a scavenging port having an open end opening out at a part of a cylinder wall defining a side of the cylinder bore, the open end communicating with the combustion chamber when the piston is near a bottom dead center thereof;
• and
• a shutter provided on the cylinder wall so as to selectively project into the open end from an upper edge thereof by moving along an axial line of the cylinder bore, wherein
• the shutter comprises a tubular portion disposed so as to be axially moveable in a coaxial relationship with the cylinder bore,
• the cylinder bore is defined by a cylinder sleeve, and the open end of the scavenging port comprises a scavenging orifice passed across a thickness of the cylinder sleeve, the tubular portion being wrapped around the cylinder sleeve in an axially slidable manner, and
• the tubular portion includes a projection received in the scavenging orifice and defining the cylinder bore jointly with the inner circumferential surface of the cylinder sleeve.