A toilet flush mechanism including a cam attached to a flush handle and a pivoting arm for controlling a tank release valve. The cam includes a lower portion engaging the lower surface of the arm, and an upper stop for engaging the upper surface of the arm to limit cam rotation and arm elevation. The arm rests on the cam lower portion such that rotation of the handle and cam in a first direction raises the arm by a first amount to contact a first portion of the stop to provide a full flush, and rotation of the handle and cam in a second direction raises the arm by a second amount less than the first amount to contact a second portion of the stop, thereby to provide a limited, water-conserving flush.