Chevr - it is not the jet portion of the power circuit that requires tuning, it is the timing which is controlled by a spring.
Generally (DO NOT ARBITRARILY MAKE THIS MODIFICATION UNTIL YOU ARE SURE IT NEEDS TO BE MADE!!!) what one needs is a weaker vacuum piston spring. Often, hobbyists will simply clip a certain number of turns from each spring thus weakening the spring. The same number must be cut from both springs. A better method is to hand wind a weaker spring of the same length with smaller wire. Obviously, if you cut the spring(s) and go too far, you are in need of new springs.
As to recommended carburetors, if you use the "search" function on this forum, you should find several threads on this subject; or give me a call during normal business hours and will be happy to attempt to answer your questions.
Jon.
