If i had things my way, i would like to see some kind of legislation requiring sellers of motorised engine kits to have their potential customers sit a test/exam requiring them to answer a series of questions, to determin if they have the correct level of competency to safely install the engine conversion, then have the bicycle presented to the retail outlet to verify if it has actually been safely installed.
Like all things where there is a potential for injury and the government with a pure love of "banning" something because there's political mileage or profit involved in forcing people to use accepted methods of transportation, it will only be a matter of time before some people (through their ineptitude or incompetence) wreck the system that allows us to have the freedom to ride motorised bicycles, .
Fabian