If you disconnect the negative terminal on a motorcycle battery and then try to start the motorcycle, several things may happen:
Loss of power: The negative terminal of a battery is typically connected to the motorcycle's frame or chassis. By disconnecting it, you break the electrical circuit, and the motorcycle will lose power. Without a complete circuit, the electrical components such as lights, ignition system, and other accessories will not function.
Ineffective starting: Since the ignition system relies on the battery to provide power, disconnecting the negative terminal can prevent the motorcycle's engine from starting. The spark plugs won't receive the necessary electrical current to ignite the fuel-air mixture in the combustion chamber.
Potential damage: Some motorcycles have sensitive electronic components that may be adversely affected by disconnecting the battery without proper precautions. Sudden voltage fluctuations or spikes can damage the electrical system or even the ECU (Engine Control Unit) if not handled correctly.
Safety features may activate: Many modern motorcycles have safety features such as immobilizers or anti-theft systems that rely on the battery's power. Disconnecting the battery can trigger these features, which may prevent the motorcycle from starting or operating normally even after reconnecting the battery.
It's important to note that disconnecting the battery, particularly the negative terminal, is not a recommended method for troubleshooting or starting a motorcycle. If you are facing starting issues, it's best to consult the motorcycle's manual or seek assistance from a professional mechanic.