For a new engine breakin period I would run what the supplier suggests as far as the fuel/oil mix, generally 20:1 of a quality 2 stroke air cooled oil. As far as the fuel/ air mix it is controlled by moving the needle up or down inside the slide of the carb. Moving the needle clip down/ raising the needle richens the fuel/ air mixture, and moving the needle clip up/ lowering the needle let less fuel in and therefore leans the fuel/ air mixture. Usually a good starting point iss the second notch from the top. Also a good idea to get a quality name brand spark plug, gap it at .020 to .025, and replace the spark plug wire and cap, it screws out of the CDI and is easily replaced at any auto parts store, just ask for a coil wire and cut it to length...
Here is an excellent thread on the carb internals..........
http://motorbicycling.com/f4/carbure...build-195.html