Sure could use more pictures and a bit more detail on removing the carb. I've had my C50 apart and worked on the rear exhaust valves, but what a pain in the a$$ getting a feeler gauge in there is. I broke the gauge twice trying to get it in.
In all honesty, I gave up after doing the rear exhaust valves. Without removing the carb there's just no way to get to the other valves that I can figure out. Even then, it looks like the feeler gauge is going to present the same problem. (Doesn't anybody make a "slim" version?)