When I stopped the Dub, I could smell cookin' oil. A close look and the valve adjustment cover was seeping some oil out on engine. I washed the area well, removed the cover and gasket. Went to NAPA and found a perfect replacement - $1.70. Been on a few long rides since replacing and the area is still nice and dry. Here's the info:

O ring 2 1/4 X 2 7/16 X 3