An improved burner and a method for combusting fuel used in furnaces such as those found in steam cracking. The burner includes a burner tube having a downstream end and an upstream end, a burner tip adjacent a first opening in the furnace, so that combustion of the fuel takes place at the burner tip, a lighting chamber adjacent to the first opening in the furnace, and a removable lighting chamber plug having a shape effective to substantially fill the lighting chamber when positioned within the lighting chamber.