The Yamaha SR400 headlight utilizes a 9003 bulb size for both high beam and low beam functions. Replacement chart data spans 2015 to 2018 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 9003 bulb is the sole headlight bulb type specified for the Yamaha SR400 across the 2015-2018 model years.
The 9003 is an ANSI-standard designation used in the United States and Canada, identifying a dual-filament halogen bulb with a P43t base operating at 12 volts.
The dual-filament design of the 9003 means a single bulb contains two separate filaments, one rated at 60 watts and one at 55 watts, serving both high beam and low beam functions respectively.
Because the 9003 handles both high and low beam operation within one unit, the SR400 uses the same bulb position and part number for both lighting functions.
The P43t base is a bayonet-style mount with a 43mm collar, which physically determines fitment and is not interchangeable with other base types such as H4 or P45t without modification.
The 9003 and H4 bulb types share the same dual-filament halogen construction and wattage ratings, but they differ in base design, making them non-interchangeable on a direct plug-in basis despite their functional similarities.