Mister Dumbass pays yet another call.
You know that rubber gasket that goes in between the generator and the engine case? (M1 model only.) Well, if you forget to install it, just be sure to wear shoes and pants you don't really care about the next time you go for a ride. And bring a quart of oil if it's going to be a long ride.
My bike turned into the Exxon Valdez immediately after some maintenance I did. The source of the leak was pretty obvious, and when I pulled the generator off, I immediately saw what was going on. Being somewhat of an older fart, I've developed a tendancy to forget things, and in this case, it was that rubber seal.
The original seal had vanished into the vast trove of junk in my shop, so I made a new one using O-ring material and good old Crazy Glue. That little contraption you see in the image above is what pushes the assembly forward against the engine case, providing uniform pressure to the O-ring and thereby ensuring a good seal.
The yellow thing you see is a sponge that was there for the shakedown, then removed. Happily, there was no need for it.