ORIGINAL: Sport_Pilot
I think the original carb is oversized. Won't run well unless the muffler is restrictive, or use a pump or regulator. Otherwise the carb is excellent.
Sport_Pilot is right, just add a pump. I have a "red head", that is the first version and I use a Perry Oscillating VP20 Pump (no drilling & tapping the backplate!). I must tell you guys that eventually I did replace the ASP carb with an OS one but not the 7D. I use the 86 carb from an OS .61 SF-P with the VP20. It works very well and throttling is instantaneous.