they come that way from the factory, it is so that you can control how the chassis flex's and how it works the left rear. i have heard that bigger drivers want to leave it open and smaller/lighter drivers may put a clamp on it to stiffen the lr of the chassis
When I ran the Nemisis chassis I had a clamp that resembled the lock collars on the axel jus a different id. At tracks that were wet I would not run the clamp and the tracks that were hard I would install the clamp to stiffen up the chassis. The Nemisis is already a pretty soft chassis as it is.
Our Early model CKS LTO kart has a torsion bar with clamps. We have a Nemesis and an old CKS, it looks like that clamp may work. Not sure if they still sell them or if they are the correct size, may be worth checking into if they are wanted. cometkartsales.com