Things i have found out include.
The bike has to be de registered. in Japan or which ever country.
You can do a personal import but its tricky as you have to own the bike in the country for 1 year. you then need proof of residency in said country and passport details before it can be shipped.
A mint bike deserves good crating so expect 2-£300 for this
asd shipping is on size of crate i dont expect more than £600
duty and vat.
the duty ect is worked out on cost of bike so if the reciet which you need. says £3500 then duty and vat is on this price.
if however you can get the dealer/ or friend to do the receit lower then duty and vat will be reduced.
also if it is listed as bike spares this only has a 2% duty levy so again would save costs but to do this you need to ship bike in bits.
There are cheap bikes in Japan and unlikely youd pay £3.500 as suggested
you need a contact like Drew in Japan
who has shipped goods but as i understand has not shipped a complete bike yet so you would need to speak to him and hopefully he can shed some light on how its done.
also
things here in the u/k at delivery port isnt plain sailing as you would need to make arrangement how the bike crate is being picked up so this means a small truck as itll need to be fork lifted on.
you then have to register it in the u/k