Thank you Justin and 33d6 for your quick replies.
Well, I thought it was an Super Sports TT engine as thats what it says on the barrel. I've attached a pic where you can make it out. I did check the engine prefix on
http://www.villiers.info/ and was confused at the fact that my bike has a KZ prefix instead of the BZ but the barrel says otherwise. I considered that the bike may have had parts replaced or mixed with other bikes, but since the bike is located in India, I'm not sure if many of these were sent to India to allow parts to be exchanged. I can't check the frame number again as the bike is in India and I currently in the US and was considering bringing it to the US. It is possible that the frame number my dad gave me is a part number rather than the actual frame number.
I am very curious about the girder fork on the bike as it looks like its steel pressed like on German bikes rather than the tubular ones on other British bikes. I googled early Excelsior bikes and most of them seemed to have the tubular type forks. Also could you suggest any websites for more information regarding Excelsiors of this period? What other differences would there be between a super sports tt and a 196 super sports engine. Is one more collectible/desirable than the other? Are these relatively common or would they be considered rare?I don't have any idea about these bikes as I'm more into pre 1955 Nortons and Triumphs, but I find this bike very interesting.
Thanks again
Norton55