The Echo site is nice, parts breakdown and everything.
From looking in the manual about the carb there might be a little hope. In the manual they show a screw inside of the idle adjustment that may be the high speed. They give it the "dont adjust this" treatment.

I do have the Ryan converted and had it running yesterday. I didnt have a small enough prop so I was just checking to see if it would fire up. Very nice. I must admit having the carb on the rear is a pain for choking but its perfect when it comes to adjusting the needles

Adam