Another tip (for the competition side), is to make sure the seat is as tight as possible, It’s not like a car seat, where you can sit and get strapped in.. In a Kart seat you need to be squeezed in hard enough that you can’t physically move, then you shouldn’t be moving around getting friction burns!
No matter what you do though, you’ll still get bruised while karting.. I’ve been racing for 7 Years, and I still normally get bruise’s and scrapes on my knees, hips and shoulders.. It’s never comfortable!
i’m sure you’ll find more help at a different website! not sure if an F1 Fan’s site is the best idea!