I have just taken out the original 500 engine and gearbox ready to fit the 650cc engine and syncro gearbox. I have just noticed that there is a sensor on the new gearbox next to the speedo socket that isn't on the original gearbox. Does anyone know what this sensor is for and how I wire it up? Or can I just ignore it?

Hi, Could it be for a reversing light?

You are correct - it is for the reversing light. If you wish, cap it with something to keep the dirt and moisture out and then ignore it.

Chris