Sorry Moto, I missed the question about import duties……..
There are no import duties payable anymore (except on second hand exhaust systems), you pay 10% gst on the purchase price of the bike ,the cost of the shipping and the insurance.
You also have to apply to import the bike through DOTARS and there is a $50 application fee. Quarantine will want to wash your bike as well,no matter how clean it is and they usually sting you $100 for that as well.
You said it was your bike already?? You may also be eligable to import it as a personal import which would allow you to register it regardless of ADR’s, but that is a whole different kettle of fish.
The easiest way to import them is to bring them in as an off road vehicle,but that way it can never be registered for road use which doesn’t matter for the bikes I import as they are all motocrossers.