Bike sold but not transferred

Gentleman, I am facing big harassment at the moment with one single mistake. I sold one bike for just Rs.8000/- to a person in Noida (UP) in Aug 2012. At that time, I and the purchaser signed at an affidavit that the bike is sold on price and will be transferred at the earliest. I have my bike and RC to him after that. Since then, due to my hectic schedule, I was not able to contact him and later forgot this chapter at all. Last month I received a challan on my Delhi address (of not wearing helmet), through which I came to know that he has not transferred the papers. Since, I shifted to Gurgaon from Noida and during that process, I lost all the documents related to sale of my bike. Now, I was filled the challan as the bike is still on my name but I am worried as I have no idea of the purchaser address or place and the bike can be used in criminal matter for which I will be legally held responsible. I have checked the Transport office and the police station but no one is giving me solution and they only say that search the man and get your bike transferred. Since I do not know where does is live in Delhi NCR now, I am stranded. Kindly help that what should I do so that now onwards I do not have any legal entity on the bike and I can be safe for future challans or other legal matters pertaining the bike.