Honda Motorcycle VT500FT Ascot Turn Signal Bulb Size
Honda Motorcycle VT500FT Ascot front turn signal bulbs measure 1034 size, while rear turn signal bulbs measure P21W and 1073 size. The replacement chart covers 1983 to 1984 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 Honda Motorcycle VT500FT Ascot uses three distinct bulb types across its turn signal positions and model years: the 1034, the P21W, and the 1073.
The 1034 is an ANSI-standard dual-filament bulb rated at 12V and 21/5W, fitted with a BAY15d bayonet base. It is classified as a variant of the 1157 and is specified for the front turn signals on both the 1983-1984 VT500FT Ascot.
The BAY15d base used by the 1034 features two offset pins at different heights, which physically prevents incorrect installation and distinguishes it from single-filament bayonet bases.
The P21W is an ECE-standard single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base. It is specified for the rear turn signal on the 1984 model.
The 1073 is an ANSI-standard single-filament bulb rated at 12V and 13W, also fitted with a BA15s bayonet base. It is described as a lower wattage variant of the 1156 and is specified for the rear turn signal on the 1983 model.
Although the P21W and the 1073 share the same BA15s bayonet base, their wattage ratings differ significantly at 21W and 13W respectively, making them non-interchangeable without affecting circuit load and signal brightness.
The 1034 uses a BAY15d base, while the P21W and 1073 both use a BA15s base. These two base types are physically incompatible, so the front and rear turn signal bulbs on this model cannot be substituted for one another regardless of voltage rating.
The rear turn signal bulb specification changed between the 1983 and 1984 model years, shifting from the ANSI-standard 1073 to the ECE-standard P21W, reflecting a change in the applicable regional standard for that position.
The 1034 is noted as a variant of the 1157, which is itself a widely used dual-filament automotive bulb. However, the 1034 carries a lower wattage rating than the standard 1157, and the two are not directly interchangeable in all applications.
All three bulb types specified for the VT500FT Ascot operate at 12V, consistent with the standard electrical system voltage used in motorcycles of this period.