When modifying a motorcycle exhaust, you may encounter various issues, such as water discharge, black dust, a rumbling noise, and white smoke. These issues can affect the motorcycle's performance, so it's important to understand their causes and address them promptly:

First, water discharge from the exhaust may be caused by condensation forming inside the pipe, especially in cold temperatures. This isn't a serious problem and usually disappears with warming. However, if water discharge persists, you may need to check the exhaust system for leaks or other issues.

Second, black dust in the exhaust is often associated with incomplete combustion but doesn't necessarily mean oil burning. Oil burning is often accompanied by blue or gray smoke. If black dust is found, check the fuel injection system for proper function and whether there are other issues causing incomplete combustion.

Third, a rumbling noise from the exhaust may be caused by incomplete combustion, poor airflow, or a clogged exhaust pipe. In this case, check the engine's combustion status and exhaust system for proper operation to ensure the motorcycle's proper function.

Furthermore, white smoke from the exhaust may be caused by incomplete combustion, a fuel system malfunction, or a problem with the engine's cooling system. Check the fuel injection system, fuel quality, and cooling system to determine the specific cause and repair it.

A clogged exhaust pipe can lead to reduced power, increased fuel consumption, and other issues. Therefore, regular exhaust pipe inspection and cleaning is crucial.

Exhaust pipe leaks can affect motorcycle performance, potentially causing reduced power and increased fuel consumption. Therefore, leaks should be promptly inspected and repaired.

Prompt repair and maintenance of exhaust pipe leaks are crucial to ensure the proper functioning of your motorcycle.