I have a Brison 3.2 on a 87" Ohio Giles 300. It doesn't seem to have hardly any mid-range. It seems to be either wide open or nearly idling. I have the throttle servo set up for full swing, and the linkage is on the hole nearest the servo center. The ball link is on the farthest hole on the carb. As the throttle stick is advanced, it slowly opens the carb butterfly, but it still runs as I described. It has the standard Walbro carb on it. It would be nearly impossible to hover down low like this. Any ideas?

Send the engine back to Garry Allison at Brison. They have recognized this problem and have a redesign for it. I have two of their 3.2's that run perfectly in the mid range.

I would suggest that you call Gary first. I also have a pair of 3.2's and it could be something as simple as a needle adjustment.