A spark-ignition internal combustion engine, ICE, system for a vehicle, comprising a two-stroke ICE, a first cylinder accommodating a reciprocating first piston operable between a bottom dead center and a top dead center, and further at least partly defining a first combustion chamber with a top end of the first piston, at least one intake port arranged at a top end of the first cylinder and in fluid communication with the combustion chamber, and further an exhaust port arranged distal from the top end of the first cylinder, a second cylinder accommodating a reciprocating second piston operable between a bottom dead center and a top dead center, and further at least partly defining a second combustion chamber with a top end of the second piston, at least one corresponding intake port arranged at a top end of the second cylinder and in fluid communication with the second combustion chamber.