Took my'79 out today for my first trip of the season. I will be doing some cosmetic work on my bike this year but didn't plan on doing too much mechanical work, didn't think it needed any.
It seemed to ride well, didn't notice anything unusual while I was riding. When I got back home I noticed a low popping, snapping noise coming from the valve cover area. It wasn't loud, which explains why I didn't hear it until I got home.
Also it seems like the #4 & #5 pipes were not very hot. I couldn't grab them and hold on but they were cooler than the other 4 pipes. I have not done a tuneup in a while. I did have a problem in the past with the #4  not firing right, I had to change the coil, that seemed to have corrected it. I am going to do a tuneup, change plugs, wires, oil, etc. Hope that helps. As for the popping noise I will have to dig deeper for that one.
Unless one of you guru's have any idea what it could possibly be? Thanks.