The Buell Lightning CityX XB9SX headlight bulb uses an H7 size for both high and low beam functions. The replacement chart covers 2005 through 2009 model years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The H7 is a single-filament halogen bulb operating at 12 volts and 55 watts, fitted with a PX26d base, which is a two-pin bayonet-style connector designed to seat the bulb at a fixed orientation within the housing.
The H7 bulb is defined under ECE regulations, making it a standard type across European and worldwide markets, and it also carries approval for use in the United States and Japan.
The Buell Lightning CityX XB9SX uses the H7 bulb for both the high beam and low beam headlight positions across the 2005-2009 model years covered in the specifications.
Because the high beam and low beam positions share the same H7 bulb type, a single replacement bulb specification applies to both functions on this motorcycle.
The single-filament construction of the H7 means each bulb serves only one lighting function, which is why separate bulbs are required for the high and low beam circuits rather than one dual-filament unit handling both.
The PX26d base is not interchangeable with other common halogen bases such as H4 or H11, so only bulbs carrying the H7 designation are physically compatible with the XB9SX headlight sockets.