A light emitting diode headlight structure for a motorcycle having a central plane with respect to a front view of the motorcycle, having: headlight LED elements (162L,R, 164L,R) for emitting low beam and high beam illumination, a headlight printed circuit board to which said headlight LED elements (162L,R, 164L,R) are mounted, a reflector assembly having low (142L,R) and high beam reflectors (144L,R), configured to reflect said low beam and high beam illumination emitted by said headlight LED elements (162L,R, 164L,R) toward the front of the motorcycle, said LED headlight structure constructed by combining said headlight PCB with an upper portion of said reflector assembly, said LED headlight structure positioned within a space connecting a headlight case and a headlight lens, and mountable on the motorcycle on both sides of the motorcycle central plane, said headlight PCB mounts at least said headlight LED elements (162L,R, 164L,R) to one plate on one side of the motorcycle central plane, said high beam illumination is emitted at the motorcycle central plane and said low beam illumination is emitted at the outside of the motorcycle central plane on one side of the motorcycle, characterized in that: an extension member is positioned forward of the reflector assembly and between said headlight case and said headlight lens, and a window structure is formed at said extension member, the window structure configured for passing portions of said low and high beam illumination reflected by the reflector assembly therethrough, wherein an upper border of said window structure is located close to an upper portion of the low beam reflector (142L,R) and is located below the upper portion of the high beam reflector (144L,R), with respect to a front view of the motorcycle, and wherein the upper border of said window structure is oriented obliquely in a downward direction toward the motorcycle central plane, wherein the headlight LED elements (162L,R, 164L,R) include a plurality of low beam LED elements (162L,R) and a plurality of high beam elements (164L,R), and the upper border of the window structure is located at a lower height than the low beam LED elements (162L,R) and the high beam LED elements (164L,R). headlight LED elements (162L,R, 164L,R) for emitting low beam and high beam illumination, a headlight printed circuit board to which said headlight LED elements (162L,R, 164L,R) are mounted, a reflector assembly having low (142L,R) and high beam reflectors (144L,R), configured to reflect said low beam and high beam illumination emitted by said headlight LED elements (162L,R, 164L,R) toward the front of the motorcycle, said LED headlight structure constructed by combining said headlight PCB with an upper portion of said reflector assembly, said LED headlight structure positioned within a space connecting a headlight case and a headlight lens, and mountable on the motorcycle on both sides of the motorcycle central plane, said headlight PCB mounts at least said headlight LED elements (162L,R, 164L,R) to one plate on one side of the motorcycle central plane, said high beam illumination is emitted at the motorcycle central plane and said low beam illumination is emitted at the outside of the motorcycle central plane on one side of the motorcycle, characterized in that: an extension member is positioned forward of the reflector assembly and between said headlight case and said headlight lens, and a window structure is formed at said extension member, the window structure configured for passing portions of said low and high beam illumination reflected by the reflector assembly therethrough, wherein an upper border of said window structure is located close to an upper portion of the low beam reflector (142L,R) and is located below the upper portion of the high beam reflector (144L,R), with respect to a front view of the motorcycle, and wherein the upper border of said window structure is oriented obliquely in a downward direction toward the motorcycle central plane, wherein the headlight LED elements (162L,R, 164L,R) include a plurality of low beam LED elements (162L,R) and a plurality of high beam elements (164L,R), and the upper border of the window structure is located at a lower height than the low beam LED elements (162L,R) and the high beam LED elements (164L,R). an extension member is positioned forward of the reflector assembly and between said headlight case and said headlight lens, and a window structure is formed at said extension member, the window structure configured for passing portions of said low and high beam illumination reflected by the reflector assembly therethrough, wherein an upper border of said window structure is located close to an upper portion of the low beam reflector (142L,R) and is located below the upper portion of the high beam reflector (144L,R), with respect to a front view of the motorcycle, and wherein the upper border of said window structure is oriented obliquely in a downward direction toward the motorcycle central plane, wherein the headlight LED elements (162L,R, 164L,R) include a plurality of low beam LED elements (162L,R) and a plurality of high beam elements (164L,R), and the upper border of the window structure is located at a lower height than the low beam LED elements (162L,R) and the high beam LED elements (164L,R).