When we dyno tune a bike, it is not unusual to get 30-40 dyno runs on a bike just to get the jetting right. A dynamometer does not lie, and it is without question the most accurate way to set up carb jetting. If you don't have a shop in your area with a dynamometer, it may be worth your while to make the trip to a place that does. If it is not possible, then you are going to have to rely on the old trial and error method. While you may find information published telling you what jet size to use on a certain bike, and it may seem to work, don't blindly believe it.
Every bike can be different.
The only way to tell is to buy a handful of jets and try them. Even if your bike seems to run o.k with the jet size recommended by someone with the same bike, you still want to install one size richer and one size leaner and see it makes any difference. Ideally, you want to find the smallest main jet that gives you the highest top speed, then richen it up one size, just to be on the safe side. Your bike should not foul the correct spark plug. Also make sure everything else is right before you begin.