I do not understand why you want to rent a motorbike if you do not want to pay money for insurance, as insurance is a must-have for any car rentals and moto rentals. Maybe there is a rental with cheaper insurance but it does not matter if you have money for the rental you need to consider that insurance will be expensive as well. I did rent a motorbike from
https://narscars.com.ua/en/kharkov-r1 this summer and paid for expensive insurance as well but I knew that if something happens to the bike that it will be covered with insurance and I will not have to worry about it. Hope you will find what you are looking for. Good Luck!