A medium pump for a motor includes a pump case with a pump cylinder and a pump piston positioned displacaebly in the pump cylinder in the direction of a pump axle. The pump piston rotates about the pump axle by running off an oblique control surface and realizes axial pump movements against the pressure of a first spring. A pump lift adjusting device is removably positioned in a guide placed transversely to the pump axle and fixedly connected with the pump case.