This PDF document will teach you pretty much everything you need to know about the workings of a carb. It won't necessarily tell you what to change when changing exhaust, filters, etc. but it tells you how the fuel gets where it needs to go.
It also explains that the 14.7:1 a/f ratio is actually the ratio between the
vaporized fuel to air. In other words, if the fuel isn't vaporizing, you've got to pump that much more fuel into the engine to get the correct mixture. That's why you have to choke a cold engine. Once the engine gets to operating temperatures, the fuel more redily vaporises and more of it is burned, so you can effectively lean out the mixture. Anyway, that's another topic.
http://www.cryscom.nb.ca/PDF_Docs/Honda_Technical.pdf
