Sorry you bought that seat, I almost quit karting because that style seat puts pressure on one particular spot. I still have scar tissue on my back bone because 2 of my ribs getting pounded from just driving smooth so take it serious. get rid of that seat and get a Deep Seat or a Rib Tech that fits properly.
FAA certified jet engine and aircraft technician,
Nicholson Speedway class champion 2001,
Yamaha KT100 Service Center,
41 years karting experience