Motorbike touring in NZ in april/may

[Snakeboy]

Hi all good people in New Zealand

I have ridden my bike from Norway to Australia where I currently am. I will however fly home for christmas and new year and come back in late january and continue another 2-2,5 months here in Australia if things goes approx as planned.
But what to do after Oz? I have reseached a bit and understand that April and May are not the best months to tour NZ as it will be a bit cool/cold in the south and chances of a good bit of rain on the northern island.

But this is probably my only chance to do a motorbike tour on NZ with my own bike. So should I do it or not - thinking mostly about it weatherwise and climatewise? If I ship the bike over from Oz lets say beginning of april and then tour 6-8 weeks of NZ this will I belive give me a good period of time to do a decent tour of NZ. But will it be too cold and too much rain to enjoy it?
Lets say I can try to be on the southern island in April and the northern in May?

Can anyone shed a bit of light on this subject?

Thanks in advance!