A two-stroke internal combustion engine has at least one cylinder (1) receiving a piston (2) and having at least one injection nozzle (4) in the form of a multi-hole low-pressure nozzle inserted in a bore (5) in the cylinder jacket (6). The multi-hole low-pressure nozzle has a nozzle plate (15) with nozzle openings (16) arranged within an enveloping circle (17) to form a common nozzle jet (11) with an opening angle (α) dependent on the inclination of the nozzle axis (12) relative to the orifice surface of the bore and preventing the nozzle jet from being applied to the cylinder jacket. A resulting vector (14) from the velocity vector (13) of the nozzle jet in the direction of the nozzle axis (12) and the velocity vector (10) of the flushing air flow in the flow main direction defines with the cylinder jacket a maximum inclination angle (γ) of 20°.

A uniflow-scavenged two-cycle engine includes: a cylinder which has a combustion chamber; a piston; a scavenging chamber that surrounds one end side of the cylinder in the stroke direction of the piston and to which compressed active gas is guided; a scavenging port that is provided in a portion of the cylinder which is positioned in the scavenging chamber and suctions active gas from the scavenging chamber to the combustion chamber in response to a sliding motion of the piston; a fuel injection opening that injects fuel gas into the active gas which is suctioned into the scavenging port; and a fuel injecting valve that opens and closes a fuel supply path through which a fuel tank, communicates with the fuel injection opening, and is disposed in an space isolated from the scavenging chamber.

A two-stroke internal combustion engine has at least one cylinder (1) receiving a piston (2) and having at least one injection nozzle (4) in the form of a multi-hole low-pressure nozzle inserted in a bore (5) in the cylinder jacket (6). The multi-hole low-pressure nozzle has a nozzle plate (15) with nozzle openings (16) arranged within an enveloping circle (17) to form a common nozzle jet (11) with an opening angle () dependent on the inclination of the nozzle axis (12) relative to the orifice surface of the bore and preventing the nozzle jet from being applied to the cylinder jacket. A resulting vector (14) from the velocity vector (13) of the nozzle jet in the direction of the nozzle axis (12) and the velocity vector (10) of the flushing air flow in the flow main direction defines with the cylinder jacket a maximum inclination angle () of 20.

A two-stroke engine includes a crankcase defining a cylinder bore, a piston moveably disposed within the cylinder bore, and a cylinder head that covers the cylinder bore. A wall surface of the cylinder bore, a piston combustion surface of the piston, and a head combustion surface of the cylinder head, cooperate to define a combustion chamber for combusting a fuel therein. A thermal conductivity reducing mechanism is disposed in thermal connectivity with at least one of the crankcase, the piston, and the cylinder head for reducing heat transfer from combusted fuel within the combustion chamber to at least one of the crankcase, the piston, and the cylinder head. The thermal conductivity reducing mechanism may include a layer of low conductivity material coating one of the surfaces defining the combustion chamber, or a void in the cylinder head and/or the crankcase adjacent the combustion chamber.

A uniflow-scavenged two-cycle engine includes: a cylinder which has a combustion chamber; a piston; a scavenging chamber that surrounds one end side of the cylinder in the stroke direction of the piston and to which compressed active gas is guided; a scavenging port that is provided in a portion of the cylinder which is positioned in the scavenging chamber and suctions active gas from the scavenging chamber to the combustion chamber in response to a sliding motion of the piston; a fuel injection opening that injects fuel gas into the active gas which is suctioned into the scavenging port; and a fuel injecting valve that opens and closes a fuel supply path through which a fuel tank, communicates with the fuel injection opening, and is disposed in an space isolated from the scavenging chamber.

Provided is a modified two-stroke engine with an intake system having a plurality of removable inserts and a cylinder liner for each cylinder bore. The inserts fit within specific cavities in the engine's cylinder bores and are aligned with corresponding intake ports, upper transfer, lower transfer and central boost ports, in each liner. Certain embodiments may include an exhaust insert for the exhaust port. The exhaust insert can be a single piece or a set of three. Also provided is an engine having a billet aluminum block, forged as one piece, cylinder bores, insert cavities, removable intake inserts, pucks to cover the cylinder bores, a cylinder head base with a ring and a cylinder head cap. The ring prevents the separation of liner from water jacket. The power output of the engine is regulated by varying the size of the inserts. Additionally, methods for assembling, tuning and modifying an engine's horsepower are provided.