The Yamaha XS850 high beam and low beam headlight bulbs both utilize a 9003 bulb size. The replacement chart covers vehicle production spanning 1980 to 1981.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 9003 is the sole bulb type listed across all headlight positions in these specifications. It is a dual-filament halogen bulb operating at 12 volts, with a high beam output of 60 watts and a low beam output of 55 watts.
The 9003 uses a P43t base, which is a three-pronged bayonet-style mount. This base type is specific to dual-filament halogen applications and is not interchangeable with single-filament bases such as P14.5s or P15d.
The 9003 designation follows the ANSI standard used in the United States and Canada. This classification system assigns a numeric code to bulbs based on their electrical and physical characteristics.
The Yamaha XS850 uses the same 9003 bulb for both the high beam and low beam headlight positions across the 1980-1981 model years. This is possible because the 9003 houses two filaments within a single bulb, serving both functions from one unit.
Because both beam functions are handled by a single dual-filament bulb, substituting a single-filament bulb in either socket would result in the loss of one beam mode. A direct 9003 replacement is required to maintain full headlight functionality.