Harley-Davidson FXSTSB Bad Boy Headlight Bulb Size
Harley-Davidson FXSTSB Bad Boy headlight bulb size specifications indicate 9003 bulbs for both high beam and low beam applications. Replacement chart data covers 1995 through 1997 production years.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 9003 bulb is the sole bulb type listed across all headlight positions for the Harley-Davidson FXSTSB Bad Boy, covering both high beam and low beam functions for the 1995-1997 model years.
The 9003 is a dual-filament halogen bulb, meaning a single physical bulb contains two separate filaments: one rated at 60W for high beam output and one rated at 55W for low beam output.
The 9003 operates on a 12V electrical system and uses a P43t base, which is a bayonet-style cap with a 43mm collar width.
The 9003 is defined under the ANSI standard and is recognized in both the United States and Canada under that designation.
The 9003 and H4 bulbs share the same physical construction and filament layout, making them functionally interchangeable in most applications, though the 9003 designation is the ANSI-market name while H4 is the ECE-market equivalent.
Because the same 9003 bulb type serves both the high beam and low beam headlight positions, the FXSTSB Bad Boy uses a single-bulb headlight housing rather than separate bulbs for each function.