U have an older motorcycle that was customized, and it's still a great ride. My only problem is a leaking primary. It never used to, but after installing a new primary chain and solenoid, the primary leaks, and I cannot figure out where. I've changed the primary cover gasket, even sealed it with Hylomar, but still I get a leak. The inner primary is vented, and even though I'm running it wet, I don't get a drop out of the vent.

Probably I know the problem you have described, and I spent a few weekends chasing it down on a friend's motorcycle. Same problem. But somehow, primary fluid was getting past that foam gasket/seal they use on the solenoid. What a mess that thing made, leaking all over the chain and frame. I seem to remember either making a gasket out of cork or using an o-ring but that's what finally stopped it.

Use silicone instant gasket, even fxes old brit leaky bikes!
Hylomar? do they still sell that?

Im not a mechanic (im an industrial electrician ) but i work alongside fitters and mechanics every day.
I suggest using the stock gasket and lightly smearing it with a product called Gasket Gue ( or gasket glue, im not 100% on the name ) it comes in a tube about the size of toothpaste and is usually a sticky blue colour and it sets once applied and bolts or screws are tightened. It remains slightly flexible and should solve any leakage past the gasket.
Im sure there are other brands that have a similar product. ( now i think about it, Loctite has a product that does the same thing )
hope this helps.
Matt...