It may be a good idea for some of you guys to read the post that Cyclic is referring to, if you haven't done so already. The post is a response to the often reported extreme richness of the ST carburetor when it is in mid range throttle positions of say 1/3rd to 2/3rds open.

If my memory serves me correctly, a poster suggested that the engine typically does not need full throttle to reach near peak revs with props that it is usually fitted with, suggesting that the carb throat diameter is larger than it needs to be. This poster went on to suggest that if you note the position where peak revs are attained and set the throttle servo ATV to this point so that it is then "full throttle", when you retune the main needle - no doubt, as Downunder suggests, the needle will need to be leaned considerably due to the higher airspeed past the spraybar and greater turbulence affording better atomisation - this new leaner setting of the main needle will extend its influence into the previously-too-rich midrange, leaning the midrange. In other words, because the main does not now need to be tuned for the relatively low airspeed condition that exists when the barrel is fully open, it can be set leaner which will have a positive effect on the normally rich mid range.

Whether or not the idle jet has an influence at this "corrected full throttle position" is a moot point. The problem we are trying to solve is a too rich midrange condition that exists when the low speed is set correctly. The key point is that we are trying to get more main needle influence into this midrange.

At the end of the day, this whole procedure breaks all the rules of correct engine tuning - it is merely an attempt at a pragmatic solution to what is essentially a flawed carburetor implementation.