Figuratively, thank goodness.
Just to reiterate the setup I'm running right now, I’ve a rebuilt E50 on a box standard maxi. It has a two shoe clutch with paz springs tightened almost all the way down to have the clutch lock on at as high a rev as possible. I have a 70cc airsal kit, a milled down head for a little extra oomf at stoplights (not that it helps my bulky self), A techno boss (trusty but rusty) and a 17mm bing carb on a magnum X intake manifold.
The E50 has been port matched to the airsal (for those doubting whether this is worth doing, acceleration before from 25-40 was ho hum at best, now it's more like "good god, this is a moped?!") Anyway, it will pull hard up to 40, and then it seems to just stop acceleration entirely. Not a gradual easing off of acceleration, a hard pull up to 40 to 41 and then it will simply stay there. It will be like faster, FASTER, FASTER!!! and stop! It's strange. The engine's at a pretty damned high rpm at 40 with only 16x45 gearing, but I know others have gone farther. I have all the ports lined up, everything's matched. What could it be? It doesn't four stroke at top speed, so I might be running ever so slightly lean. But I've a 90 jet in there now, the next size up is a 94 and it splutters with that in.
Oh, and from a dead stop if I open the taps too quickly, the bike will splutter and die. But if I open the throttle slowly, it seems to stop chugging, and start howling up to speed. The needle is at its leanest setting right now, as I was having flooding issues before I got the new float valve.