The D-400 series engine or the Iron Horse engine was a light-duty 2-stroke engine used for powering lawnmowers produced in the 1960s to the early 1980s. D-400 engines were single-cylinder engines designed and manufactured by the Outboard Marine Corporation (OMC; Johnson and Evinrude) for Lawn-Boy and Masport. The D-400 engines displaced 109 cc, generated 2.61 kW of power, and operated in the range of 2400-3300 RPM. The engines have a distinctive rectangular cowling that has created a nickname of Brick-top mowers. Another distinctive feature is the two-finger vertical recoil starter. The kidney-shaped muffler and exhaust unit is mounted beneath the mowers' deck and gives the engine a small, low profile design when compared to the newer and more powerful lawnmower engines. The ignition syste