On the spare barrel I got with an old bike, (with no key also). There`s a number stamped on the face where the steering lock bolt pokes out.

M & P do replacement ignition barrels too. You`d have to find a model which shares the same barrel as the NSR. Should be about £35 for one from M & P.

I`ve had a locksmith cut me a key from a lock barrel before. They just need to know which is the correct blank for the lock. Depends on who you go to. Some will attempt it, others won`t.