It’s not about speed per se. The difference between 4 and 2 is how the power is delivered and what that translates into as far as driving is concerned. Watch some YouTube vids of folks racing 4 stroke. You will see that it appears to be all about maintaining momentum and any little mistake costs you dearly, not in that moment, but a few turns later. It really requires a controlled and thoughtful driving style.
2 stroke is a lot more “let er rip”. You can cover up small mistakes (to a point) with throttle.
Soooo… if you have ambition to be a good racer, you will be better served learning how to drive well in 4 and then taking those skills to 2 and being the guy that is fast and controlled.
I started karting in 2 stroke and I can safely say that I would likely be a better, more strategic driver if I had started in 4.
But to answer your question… at etown I hit 63 on the straight and 72 at NJMP. Last I rode a 4 was at OKC (fun!!!) and I think in the fast bits I was in the 50’s.
Do not underestimate how much you need to spend in 2 vs 4 as well. 100cc 2-stroke seems more economical than 125cc TAG but it’s probably way more costly in a variety of ways than 4 stroke sealed engines that get literally thrown away after a few seasons.
Here’s an example of 4 stroke racing by the son of one of our own. Notice the general lack of drama.