What technical modification to a motorbike will generally void the issued operating licence?

Your selection of the first two options is correct. In Germany, any modification that alters a motorbike's performance specifications, such as changes to the gear ratio of the pinion and chain wheel or alterations to the engine power, can void its operating licence. These regulations are in place to ensure that vehicles meet safety and environmental standards, and unauthorized modifications may affect the handling and performance of the motorbike. Changing these foundational aspects can also lead to non-compliance with the vehicle's original type approval, impacting insurance and liability in case of an accident. Therefore, it's important to adhere strictly to these regulations to maintain legal and safe operation on the roads.