Hi Hils I have been posting on fb in reply to your Turkish friend who says he has now legally insured your scooter without you taking out residency, he has now deleted the post as I pointed out that you can get insurance but it will not be legal, I did say that you needed residency to legally own a motor vehicle he insists that law is only for new vehicles, he is wrong and so am I, you do not need residency but what you do need is a Kimlik which is a Turkish ID number, now the only way I know of getting your Kimlik is to take out your residency, I can remember now on my many visits to the traffic police this is what they and Mugla and the insurance companies were asking for, I realised my mistake after reading a post from KKOB who pointed out that the law requiring your Kimlik came in to force in 2010 and KKOB certainly knows his stuff regarding what you can and can not do in Turkey, as I pointed out to your friend you may have tax and insurance but if you are stopped by the traffic police or have an accident they will want to see your Kimlik, after I got my residency I could not get insurance until I got my Kimlik.
I do hope this helps it took me nearly 12 months to sort all this out but once I had residency and Kimlik no problem.