If your centrifugal clutch is not engaging, there are a few potential causes. First, check to see if the engine is running at the correct RPM. The clutch will only engage when the engine is running at or above a certain speed, typically between 1,000 and 2,500 RPM. If the engine is not reaching that speed, it could be due to a problem with the spark plugs, fuel system, or other components. Another possibility is that the clutch itself is worn out and needs to be replaced. Finally, make sure that there is enough tension on the spring inside the clutch assembly. If there isn't enough tension, the clutch won't engage properly.