Abstract: A stepped-piston, internal-combustion engine includes at least one cylinder, each cylinder having a working part of lesser diameter defined by a cylindrical wall and a pumping part of greater diameter, a piston slidable in each cylinder, a receiver which is partly delimited by the cylindrical wall of the working part of each cylinder and which extends at least partly around each working part, working inlet ports in the cylindrical wall and extending between the working part of the cylinder and the receiver and valve means to control the entry of charge into the pumping part of each cylinder and the transfer of charge from said pumping part to the receiver, and wherein the admission of charge into the working part of each cylinder from the receiver is controlled by the uncovering of the working inlet ports by the working part of the piston.