Well i did order the asp 1.08 carb. Probably take s month to get herr though. I was digging around in my rc closet and came across an old tower hobbies .61 motor. I checked t he size of the carb opening and it was 15mm just like my super tigre. So i figured i would try the carb and see if it would work on the st 90. Well it did work much to my surprise. And after a little tuning it worked very well. My st will litterilly idle at a very slow idle all day long. I dont have a tach so i dont know the rpms on the top end but it seemed to be running very well. The inside diameter of the carb thtoat is about 5mm smaller than the super tigres so im probably not getting all the motors capible of. But it runs!!!