Manco Thunderbird hesitates

Any ideas on how to adjust the carb etc on the Robin 4hp engine for the Manco Thunderbird so that it does not sorta hesitate at top speed? Once you reach top speed, it feels like it wants to go faster then backs off and it keeps sorta hesitating. I'm guessing it's something with the idle? It's a brand new carb I installed and I did not make any adjustments as I am not sure which screw does what? Also a new Spark plug which came pretty much already w/ correct gap. Any suggestions would be great. TIA
Hitting the governor, perfectly normal.
You can drag the brake briefly to get it back on the pipe so to speak, but it will reach the limiter over and over regardless.
Figured as much. You see the same type of thing like when you are driving those gas powered golf carts. They feel like they wanna go then you hit that ceiling and it backs off. Makes you want more speed. lol. Wonder what the top speed is on this thing? Feels like maybe around 25-30mph?