ORIGINAL: Dennis Flora
If the carbs are designed poorly, then the carbs are designed poorly, but I think most problems are tuning issues.
If that's the case, why is it that changing carbs seems to solve most people's problems almost immediately.
And why is it that you almost never hear of other manufacturers (such as OS or ThunderTiger) making engines that are so hard to tune they have a good percentage of customers complaining about the poor midrange? People seem to be able buy OS/TT engines, install them, tweak the needles and fly with perfect throttling and reliability. Throw an OS/TT carb on an ST and you get the same situation. So is it bad tuning or bad carb design? I think the answer is obvious.
A lack of back pressure alone will make it so you need to run the needles much further out than the norm. These carbs were designed to operate correctly with the stock muffler, which has one small opening. I hear alot of folks complaining about a rich midrange, or a bad transition, but no mention of the muffler their using.
All those having problems at our club are using the stock-standard mufflers. I've found that the transition can be improved slightly by going to a mousse-can muffler with the ST90, but it's still not good enough to be considered acceptable when compared to other brands.