The red Honda VFR750F moto cross off road bike had been advertised for sale on Ebay by its owner and the potential buyer made contact and arranged to visit the owner in Ganstead lane, Ganstead, Bilton with a view to buy the machine.
The man attended at the address and went with the owner into the garage to have a look at the bike.
The suspect said he wanted to check the gear box on the bike so climbed on and then drove off from the address.
No sale had been agreed and the man did not leave any details or any money in payment.
The thief is described as a white man, aged mid 20s, thin build, with very long hair and about 5ft 7ins tall.
The incident happened between approximately 1755hrs and 1805hrs on Tuesday 19 March.
Anyone with information about the crime or where the stolen bike is now is asked to contact Humberside Police on the non emergency number 101 referring to crime number 1963702 or call Crimestoppers anonymously on 0800 555 111.