My parents came up today and while here my dad took a look at the R50. When we had it running he asks for a long screwdriver. I asked "why?" and he replied "I want to listen to the engine." I looked at him like he was nuts and fetched a screw driver. He pressed the tip against the valve cover near the rocker and put his ear to the handle. Mechanic's stethoscope, neat! I then talked him into taking it for a spin (this wasn't hard) and fitted him with all my safety gear, which caused some grumbling until I pointed out that not only was he riding the bike for the first time, but it had new as yet untested brakes. He took it up and down the street a couple of times and came back with a huge grin.
Later I took the bike out myself so I could go visit my nephew who has grown so much in just a couple of weeks. He's just figured out how to use his eye brows and it's seriously cute.
Anyway, the bike definitely runs better with the new air cleaner and the plugs show that the engine is burning a lot cleaner. Now I just need to fix the timing and maybe adjust the valves.