Honda Motorcycle NX250 front and rear turn signal bulbs utilize a P21W bulb size for both applications. The replacement chart covers 1988 to 1990 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 P21W is the sole bulb type specified for the Honda Motorcycle NX250 across all listed model years and positions, covering both front and rear turn signals from 1988-1990.
The P21W operates at 12 volts with a 21-watt output, classifying it as a single-filament bulb intended for signalling functions such as turn indicators.
The P21W uses a BA15s bayonet base, which is a single-contact bayonet fitting with a 15mm collar width. The single-contact design reflects its single-filament construction, as opposed to the dual-contact BA15d base used on two-filament bulbs.
The P21W is governed by ECE regulations, a standardized framework recognized across Europe and numerous other markets worldwide, meaning the bulb conforms to internationally defined performance and construction criteria.
Because the front and rear turn signal positions on the NX250 share the same P21W specification across 1988-1990, the bulb is interchangeable between those positions without modification.
The BA15s base type is not interchangeable with the visually similar BAY15d or BA15d bases. Substituting a bulb with a different base configuration would result in an incompatible fit regardless of matching voltage or wattage.