Honda Motorcycle CB650 front turn signal bulbs use 1034 size while rear turn signal bulbs use P21W size. The replacement chart covers 1981 to 1982 production 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 Honda Motorcycle CB650 uses two distinct bulb types across its front and rear turn signal positions for the 1981-1982 model years: the 1034 at the front and the P21W at the rear.
The 1034 is an ANSI-standard bulb used in the United States and Canada. It operates on 12 volts with a dual-filament configuration rated at 21/5 watts, and it mounts via a BAY15d bayonet base.
The dual-filament design of the 1034 means it carries two separate circuits within a single bulb, typically serving both a higher-intensity and a lower-intensity function.
The 1034 is a variant of the 1157, a widely used automotive bulb. Despite this relationship, the two are not always interchangeable, as minor differences in filament position or base pin spacing can affect fitment and function.
The P21W is an ECE-standard bulb recognized across European and international markets. It operates on 12 volts with a single filament rated at 21 watts, mounted on a BA15s bayonet base.
The BA15s base of the P21W differs from the BAY15d base of the 1034. The BA15s has a single locating pin, while the BAY15d has two offset pins. These bases are not interchangeable.
The single-filament construction of the P21W means it serves one circuit only, which is consistent with its dedicated signalling role at the rear turn signal position on the CB650.
The split between ANSI-standard front bulbs and ECE-standard rear bulbs on the same vehicle reflects a mixed-specification configuration, which has direct implications for sourcing replacement bulbs in different regional markets.