You can only do the rhodes trip once. You cant just keep poppin over to renew the visa as the bike is classed the same as a car. 6 months in and then 6 months out. You can keep the bike in Turkey for 180 days per year. You can do the 6 months in 6 months out (if the greeks let you) twice and then that is it.
To import it permanently you need a work permit or retirement visa and submit a huge deposit with Turing. If you dont have either of those permits then there is no way you can permanently import it.