Honda Motorcycle NC750X front turn signal bulbs measure P21/5W in size, while rear turn signal bulbs measure P21W in size. The replacement chart covers 2018 to 2020 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 NC750X uses two distinct bulb types across its turn signal positions: the P21/5W at the front and the P21W at the rear, a split that holds consistent across the 2018-2020 model years covered in these specifications.
The P21/5W is a dual-filament bulb, meaning it carries two separate filaments within a single envelope, allowing it to serve more than one lighting function simultaneously. Its 21W filament handles the turn signal function, while the 5W filament serves a secondary role such as a position or parking light.
The P21W is a single-filament bulb rated at 21W, dedicated solely to one lighting function. In the rear turn signal position of the NC750X, it operates exclusively as a turn signal without a secondary output.
Both bulb types conform to the ECE standard, a regulatory framework recognized across Europe and numerous other markets worldwide, governing performance and safety requirements for vehicle lighting components.
The P21/5W uses a BAY15d bayonet base. The offset pins on a BAY15d base are positioned at different heights, which physically prevents incorrect insertion and ensures the two filaments are connected to the correct circuits.
The P21W uses a BA15s bayonet base, a single-contact design with symmetrically placed pins. Because the NC750X rear turn signal requires only one filament, the simpler BA15s base is sufficient for that position.
The base types of the two bulbs are not interchangeable. A BA15s bulb cannot seat correctly in a BAY15d socket, and a BAY15d bulb will not fit a BA15s socket, making cross-position substitution between front and rear turn signal bulbs on the NC750X physically incompatible.
Both bulbs operate on a 12V electrical system, which is standard for motorcycles in this class and consistent with the NC750X platform.