The Yamaha TDM850 headlight uses an HS1 bulb size for both high beam and low beam functions. The replacement chart covers vehicle production spanning 1992 to 1993.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The HS1 is the sole bulb type specified across all listed positions and years for the Yamaha TDM850, covering both high beam and low beam headlight functions for the 1992-1993 model years.
The HS1 is a dual-filament halogen bulb, meaning a single physical unit contains two separate filaments to serve both high and low beam functions within one housing.
The HS1 operates at 12 volts with a 35W/35W output rating, where each wattage figure corresponds to one of the two filaments.
The HS1 uses a PX43t base, a bayonet-style fitting specific to motorcycle headlight applications, which is not interchangeable with common automotive bulb bases such as H4.
The HS1 is governed by ECE (Economic Commission for Europe) standards, a regulatory framework recognized across Europe and numerous other markets worldwide.
Although the HS1 and H4 are both dual-filament halogen bulbs with similar voltage and wattage ratings, they use different base types and are not interchangeable despite their functional similarities.
The identical HS1 specification across both the high beam and low beam positions for 1992-1993 reflects the use of a single dual-filament bulb to fulfill both functions, rather than two separate single-filament bulbs.