weird power issue
 

weird situation. very hard to get rpms up but as soon as it hits 2400 rpm every time it then rockets off.
But, can't get past 4100 rpm. Overall, I don't care if it doesn't go over 4100, but I would like the bottom hole shot.
I have a new fancy 4 blade 15 pitch prop to fix hole shot (this worked until a day ago). Nothing much changed in the engine etc. The carb? The accelerator pump is working (I can see spray). It's weird that the power really kicks in at exactly 2400 each and every time. I am able to finesse it sometimes to go up semi-smoothly, but if I give it full throttle from the start, then is usually bogs until 2400. Would the carb be so precise? Almost sounds like a timing thing.