Question about '79 KZ650

I have a 1979 KZ650 SR and am in the process of rebuilding it. I am fairly new to motorcycles. On the front tube, where the fork pivots, there's a socket that the key fits into, with a swivel cover on it. I thought it might be for the turning lock, but the key won't turn in it at all, no matter where the fork is turned. Can someone enlighten me as to what it is?

It's used to lock your forks when the bike is parked, so some one would not be able to ride off on your bike.
The original ignition key should fit that lock.

Then again, it's been sitting for 27 years.
I used to use the lock on my B1 way back in 1988, but I think the last time I tried it I could not get it to work either.
:S

That's what I thought, maybe the cylinder is just stuck.

It's probably just stuck. I haven't used one for 20 yrs, and memory is not all that great on the subject, but the key would have to be turned with the handlebars in the correct position then the lock would push in and a pin would be extended locking the bars. There were two problems to this, it seemed like locking was easy, sometimes unlocking was not and even a mildly strong guy could simply apply force to the bars and break the lock. Not worthwhile to use either way.

That's why I quit using mine.
I can't think of anything worse than being stuck somewhere because I couldn't unlock my steering.
:huh:

Hey thanks, guys, I wasn't really too concerned about it, it was mainly a curiousity/engineer 'hey what does that do' thing. You guys rock!