I'm not a big fan of certain "jet kits". Some of them come with a very light spring for the vacuum piston which causes it to react extreemly fast. What that does is cause a rich condition in the low rpm range. There's also a kit out there that gives you a new emulsion tube with only one hole in it in stead of five.Talk about a screwed up signal to the main jet!
I leave all the factory parts in the carb,but re-jet it as needed. Depending on where you live and what mods have been done to the rest of the bike the low speed will be somewhere between a 45 and a 48, and the main will be somewhere between a 175 and 195. One thing that I do modify is to limit the pump shot. That thing puts a ton of fuel in there. Cut it down to about half the travel, and also remove the low speed adjustment plug under the carb so you can trim your idle mixture. That should be at about two and a half turns out as a starting point.Then just adjust it for best idle quality.
The CV carbs are great carbs. H.D. has 44mm and a 51mm version. I think Yamaha offers a 58. That will move some air! I've even built a few dual carb engines with them. They were fun!