Dear Brother
ask the seller for a photo copy of registration documents of bike and its authority letter(sale invoice given to buyer by the showroom managment on the behalf of bike company)and bring them to execise and taxtation department for confirmation.not only get the confirmation of current owner as well as all the previous owners and also asked the seller for all the transfer letters starting from first owner to the current owner.
further more also get confirmation from CIA in order to assure that this bike is not used in any sort of criminal activity like bank robbery,decoity and street crimes.
regards