The way I found out my points cover was leaking, is that I nursed a sickly running bike home in the rain one day, and removed the cover to find water inside.
Before I came upon the neoprene solution, I avoided riding in the rain. Still, I got caught one day and parked it in the garage for the night as it was. Next morning, it ran fine on startup, but half way to work it ran badly again, with no rain or water on the roads!
The heat from the engine turned the water to steam, whereupon it condensed on the slightly colder points. The water bridge across he points keeps its respective coil from achieving full charge, and the plugs don't fire reliably. Dried off the points and it ran fine. I made the neoprene gasket that night.
FYI, the bottom of the points compartment is machined to drain water out the bottom, regardless of gasket integrity. So, the compartment is not supposed to be hermetically sealed. I my case, simply using the garden hose in the driveway didn't effect the poor sealing gasket on my bike. It wasn't until water had pretty good momentum, that it would finally seep past, like highway speeds. With the neoprene, pressure washing left it dry inside. Further, the engine warm up cycle comes into play as there is a period where the engine is hot enough to make steam vapor, yet the points are cold enough to have condensation form on them.
Good luck finding the cause of your run issues!
