Honda Motorcycle CB750SC Nighthawk Turn Signal Bulb Size
Honda Motorcycle CB750SC Nighthawk front turn signal bulbs measure 1034 in size, while rear turn signal bulbs measure P21W in size. The replacement chart covers 1982 to 1983 production 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 CB750SC Nighthawk uses two distinct bulb types across its turn signal positions: the 1034 at the front and the P21W at the rear, across both the 1982-1983 model years.
The 1034 is an ANSI-standard bulb used in the United States and Canada. It operates at 12V with a dual-filament output rated at 21/5W, and it mounts via a BAY15d bayonet base.
As a dual-filament bulb, the 1034 carries two separate wattage ratings. The higher filament (21W) typically serves the turn or brake function, while the lower filament (5W) serves a secondary purpose such as running light operation.
The 1034 is a variant of the 1157 bulb. While the two share a similar design lineage, they are not confirmed as interchangeable in this application without verifying base and filament compatibility against the vehicle's socket specifications.
The P21W is an ECE-standard bulb used in European and worldwide markets. It operates at 12V with a single-filament output rated at 21W, and it mounts via a BA15s bayonet base.
The BA15s base of the P21W and the BAY15d base of the 1034 are physically distinct. The BAY15d base features offset locating pins to prevent incorrect insertion, whereas the BA15s base has symmetrically placed pins, making the two bases non-interchangeable.
The rear turn signal of the CB750SC Nighthawk uses the single-filament P21W, which is dedicated solely to signalling rather than serving a combined lighting role.
The front and rear turn signals on the CB750SC Nighthawk use different base types, meaning the front and rear bulbs cannot be substituted for one another regardless of wattage similarity.