Pics of my new project along with a question

[dj420a]

I won this cherry on Ebay for a 150 bux and I did get it running. It actually runs really well, better than my 92. It only has 5042 miles on it, but as you can see it needs plastic, a front wheel and forks. The rest I took off to inspect and clean.

My question has to do with this first pic. The allen bolt that is on top of the left side of the head is leaking oil. What is it for and is there a gasket in there that can be changed if I cant tighten it enough?

Thanks guys
DJ