So my neighbor got a new honda 500 4x4 (but that doesen't matter)
So I'm out riding on my bike (honda e22 clone, might be a supersize panther110, no one has ID'd it yet)
Anyway, so I pop a wheele and BAM, I'm leaking oil, or oil/gas. It comes out when wheeleing and acts fine when flat. It comes out of a plug about 1-1.5'' accrost with a bolt head on it. I think it covers the valve lash bolt.
Visual inspection doesen't show any cracks, but I know I saw it coming right out of the center (where there are no cracks)..... ya, anyway, I don't know what that part is called, or where to find it.
Here's a picture. (hope this works)

 

Here's an update.
Found an image that shows clearly the part.... but it's just labeled cap.
It's #14