It has been my experience that seat struts do transfer weight to their respective corner. I have not heard of them preventing weight transfer. And when a seat strut has broke, my drivers notice the lack of transfer.

Same story for the weight up high. It changes the center of gravity and tends to help the kart “lean” more in the turns (transfer weight), which is especially helpful when your driver is small. Now, if your driver is more normal sized or taller, I definitely would not put the weight high on the seat; rather, I’d put it as low as possible.

Seat struts do both. They stiffen the relationship between the seat and the frame, but they increase weight transfer because you’re forming that much more direct connection from the seat to the bearing hangers.

I’ve seen karts get massive inside rear wheel lift with no struts on, but they can’t maintain that lift because the outside tire isn’t being driven into the track surface. The lift is coming purely from chassis flex in that case, not necessarily from weight transfer.

I would say 95% of sprint karts with Yamaha-level power or higher are going to be running at least one additional strut per side. Anything higher than Yamaha it’s basically a necessity. Sometimes you can run without them in Yamaha depending on track conditions. On a 206 I would test it both ways and see what it does. I know my dad runs without them, but given his experience (or lack thereof), I don’t know if he’s a good benchmark.

Regarding weight placement, Jim was basically spot-on. I’m smaller (5’7″, 130lbs) so we always start with our weights at the top of the seat.