Kawasaki KFX50 Tail Light Bulb Size

The Kawasaki KFX50 tail light uses bulb sizes P21W and P21/5W depending on the specific model configuration. A replacement chart covering 2007 through 2022 documents the bulb size specifications across the vehicle's production years.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
2021-2022	P21W
2019	P21/5W
2013-2017	P21/5W
2007-2009	P21/5W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W
ECE standard (Europe & worldwide). Dual-filament signalling bulb with BAY15d bayonet base. 12V, 21W/5W.	P21/5W

Other Locations

Additional Notes

The P21/5W is the predominant tail light bulb across the Kawasaki KFX50 specification range, appearing in nine of the eleven model years listed, spanning 2007-2009 and 2013-2019.
The P21/5W operates on a dual-filament design at 12V, with one filament rated at 21W and a second rated at 5W, allowing a single bulb to serve two distinct lighting functions simultaneously within the tail light assembly.
Its base type is the BAY15d bayonet fitting, which is an offset double-contact base. The offset pin positions prevent incorrect insertion, as the two pins are set at different heights around the base.
The 2021-2022 Kawasaki KFX50 transitions to the P21W bulb, which is a single-filament variant rated at 21W on a BA15s bayonet base.
The BA15s base of the P21W uses two symmetrically placed pins, distinguishing it physically from the BAY15d base of the P21/5W. These two base types are not interchangeable despite sharing the same 15mm base body width.
Both bulb types conform to ECE standards, indicating they meet European and internationally recognized automotive lighting regulations.
The shift from P21/5W to P21W between the 2019 and 2021 model years represents a change from dual-filament to single-filament tail light operation, which reflects a difference in the circuit design of the tail light assembly between those model year groups.