When you squeeze the brake lever on your motorcycle and notice that the headlights get a little brighter, it is likely due to a phenomenon called "voltage drop."
Motorcycles often have a wiring configuration where the headlight circuit and the brake light circuit share a common electrical connection or fuse. When you apply the brake and activate the brake light, it creates an additional electrical load on the circuit. This extra load can cause a temporary decrease in voltage available for other components, such as the headlights.
The voltage regulator regulates the charging system's output to ensure a consistent voltage supply to the various electrical components, even under varying loads. In normal circumstances, the voltage regulator compensates for the additional load created by the brake light, and the headlights should not dim noticeably.
If you observe a significant dimming or fluctuation in the headlights when you activate the brake, it could indicate an issue with the electrical system, such as a faulty voltage regulator, a weak battery, or loose connections. In such cases, it is recommended to have the electrical system inspected by a qualified mechanic to diagnose and address any underlying problems.
It's important to maintain a properly functioning electrical system on your motorcycle to ensure optimal visibility and safety while riding.