Honda Motorcycle CB750K front turn signal bulb uses 1034 size while rear turn signal bulb uses P21W size. Replacement chart covers 1981-1982 production years with 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 CB750K uses two distinct bulb standards across its front and rear turn signal positions for the 1981-1982 model years.
The front turn signal on the CB750K (1981-1982) takes the 1034 bulb, an ANSI-standard type used in the United States and Canada.
The 1034 is a dual-filament bulb operating at 12V with a 21/5W output and a BAY15d bayonet base, which features two offset pins to ensure correct orientation during installation.
The 1034 is a variant of the 1157, meaning the two types share a close relationship in design, though they are not confirmed as interchangeable within these specifications.
The rear turn signal on the CB750K uses the P21W bulb, an ECE-standard type recognized across European and worldwide markets.
The P21W operates at 12V and 21W through a single filament, distinguishing it functionally from the dual-filament 1034 used at the front.
The P21W uses a BA15s bayonet base, which has a single pin and no offset, making it physically incompatible with the BAY15d socket used by the 1034.
Because the 1034 and P21W use different base types, the front and rear turn signal sockets on the CB750K are not interchangeable with each other.