Broken crankcase bolt. How boned am I?

Full disclosure: this is my first motorcycle, I'm a decent car mechanic but I've just entered the motorcycle world with this project bike.

Hi all, I just picked up a running and riding 1977 KZ750 twin and I'm excited to get it fixed up and looking and running as good as possible. It's not without it's minor issues, but I just noticed something that I think could be major.

With the bike running, I noticed this bolt head spinning. I reached down and grabbed onto it and it pulled right out. Great. Looks like someone snapped it before I took possession. How boned am I? I was planning on doing a full gasket replacement, but extraction a bolt this small has me worried.
Anyone have any similar experience they can share? Or maybe just some reassurance that the engine isn't a ticking time bomb without this bolt? 

It should be replaced but it won't go BOOM. You'll have to split the cases to do it. I'd silicon it in until you know if you have to go in there.
Steve

+1 to what Steve said. I wouldn't worry about it until it's necessary to split the cases, there are plenty of other fasteners holding them together. I doubt if one 6mm case bolt missing would even cause an oil leak.

Mike

Thanks for the reassurances. I'm still waiting for my manual to come in. Plenty more to do in the meantime

You don´t have to wait for it, your service manual is here: kzrider.com/modules/ServiceManuals/Kawas...l%20KZ750%20Twin.pdf

Thank you! I went ahead and ordered the manual though, something about paper is easier to read/manipulate to me