The Buell S3 Thunderbolt headlight bulb uses a 9003 size for both high beam and low beam functions. The replacement chart covers vehicle production spanning 1997 to 2001 with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Buell S3 Thunderbolt uses the 9003 bulb for both its high beam and low beam headlight positions across the 1997-2001 model years.
The 9003 is a dual-filament halogen bulb, meaning a single bulb contains two separate filaments: one rated at 60W for high beam output and one rated at 55W for low beam output.
Because both headlight positions share the same 9003 bulb type, a single replacement bulb serves both functions within the same housing.
The 9003 bulb operates on a 12V electrical system, which is standard for motorcycle applications.
The 9003 uses a P43t base, a bayonet-style mount with a 43mm flange that physically locks the bulb into the headlight housing.
The 9003 designation follows the ANSI standard used in the United States and Canada. It is functionally equivalent to the European H4 bulb, though the two designations originate from different regional standards bodies and packaging may differ.
The H4 and 9003 share the same P43t base and filament wattage ratings, but substituting one for the other warrants verification of housing fitment before installation.