The KTM 250 EXC-F headlight bulb uses an HS1 size for both high beam and low beam functions. The replacement chart covers 2017 to 2019 model years 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 HS1 bulb type is used across all listed positions and model years of the KTM 250 EXC-F, covering both high beam and low beam headlight functions for the 2017-2019 period.
The HS1 is a dual-filament halogen bulb, meaning a single physical bulb contains two separate filaments, one serving the high beam function and one serving the low beam function.
The HS1 operates at 12 volts with a 35W/35W output rating, where each wattage figure corresponds to one of the two filaments, both rated equally in this case.
The HS1 uses a PX43t base, which is a bayonet-style fitting specific to motorcycle lighting applications and is not interchangeable with automotive bulb bases such as H4, despite the H4 sharing a similar dual-filament halogen design.
The HS1 is governed by ECE (Economic Commission for Europe) standards, making it a regulation-compliant bulb type across European markets and many other regions that adopt ECE lighting rules.
Because the KTM 250 EXC-F uses a single HS1 bulb to handle both beam functions, replacing the headlight bulb on this model addresses both the high beam and low beam simultaneously.