Noticed this today. I threw a 1/2" nut in it and it's fine but should I be worried? Or am I good to go?

I can say I really measured it out... It went on easy with no extra torque... it was an extra bolt that I compared in an caliper to the other

chasethorn wrote on 06/26/15 at 21:03:04:

This leak is fairly common. (losing the nut is not so common, but not surprising.)

You may want to pull that nut off, clean the area around the stud,  and put a dab of RTV sealant in the threads and on top of the nut so it seals between the nut and the cylinder. Let it set overnight. The sealant will also prevent the replacement nut from escaping.

Come to think of it, you may want to spend a few minutes with a flashlight and look for the original nut in, under or around the starter and drive pulley.

Then, check for oil leaks once a week for 2 or 3 weeks. It will be most obvious on the left side, as the oil slithers down towards the side stick.

The bad thing about fixing oil leaks is that it requires cleaning an air cooled engine fins. The good thing about fixing oil leaks is that it requires riding the motorcycle often to make sure you fixed it.