An exhaust system for a two-cycle engine includes an exhaust conduit having both a bypass port and a regulator port for discharging exhaust gases to atmosphere. The bypass port has a fixed size but the regulator port has a variable size that varies over the range of engine speeds. Within a low range of operating speeds, the regulator valve is at least partly closed. Within a mid range of operating speeds, the regulator valve is progressively opened with increases in the operating speed. Within a high range of operating speeds, the regulator valve is progressively closed with further increases in the operating speed.