The Hirth 2704 and 2706 are a family of in-line twin cylinder, two stroke, carburetted aircraft engines, with optional fuel injection, designed for use on ultralight aircraft and especially two seat ultralight trainers, single seat gyrocopters and small homebuilts.
[5] The 2706 was developed as a competitor to the 64 hp (48 kW) Rotax 582 and is similar to the Rotax powerplant in being a two-cylinder in-line engine, with dual capacitor discharge ignition, although it is air-cooled, compared to the 582's liquid cooling.
The 2704 was developed from the 2706 as a de-rated version to compete with the 50 hp (37 kW) Rotax 503.
[1][2][3] Both the 2704 and 2706 use free air or fan cooling, with dual Bing 34mm slide carburetors or optionally fuel injection.
The cylinder walls are electrochemically coated with Nikasil.