I am actually wanting this bike to be completely road legal, yep for those that know me this might seem a bit strange. A bicycle with an engine on it does it really have to be legalised ....well yes actually.
If it has less than 300kw power (just to let you know thats very little power) then you would not need to make it legal. Its got a lot more than that so will need to "do the right thing".
It is actually not that complex, although I am yet to go through the process. I have researched the internet and emailed the good people at NZTA and got a very fast clear response.
The bike will require being registered as a moped, that is provided it is less than 50cc and does not exceed 50kph. I my view that means that you are not allowed to drive it any more than 50kph but that doesn't mean that you can get up to 50kph really fast and have the potential to go much faster, not that I would ever drive exceedingly fast (although my 14 years as motor racing driver might cloud your thinking).
The bike will require a few things, lights, reflector and horn and be relatively road worth, which I am sure I can manage.
Here is the fact sheet if you are interested - http://www.nzta.govt.nz/resources/factsheets/43/mopeds.html
Once I have got through the process I will update you on just how arduous the process is !