I’ve been working through something just like this. So far I’ve tried gearing shorter and playing games with the pedal in the problem corner, both of which do help. I’ve checked the frame for twist and it’s slightly twisted the wrong way to cause my issue, it’s lifting the inside rear more in that direction, maybe it drops too soon. Obsessively clean the power valve.
Anyway my scenario matches Walt’s description, a fast S, short straight, then hairpin. What would you do to the carb? My guess is:
Raise the fuel level in the bowl.
Replace needle valve.