What technical modifications to a two-wheeler could result in the withdrawal of the vehicle’s type approval?

You selected fitting customised handlebars and changing the wheel/tyre combination, which are both correct. Modifying a two-wheeler's handlebars or wheel/tyre combination can impact its safety and handling, possibly making it no longer comply with the approved technical requirements. This can lead to the withdrawal of the vehicle’s type approval, meaning it is no longer legally allowed on public roads until inspected and potentially re-approved.

On the other hand, installing an identical engine does not affect type approval because it doesn't change the vehicle's characteristics as long as it matches the original specifications.

Always remember: modifications that alter the technical properties or safety of the vehicle may require official testing or could cause loss of type approval. If in doubt, check first before making technical changes.