The engine side painted strut should generally not be moved. Its the other side that you will bend inward. Using axle as a lever is a good method. Get it so there is about 1/4″ of space between the struts and the seat, unless the seat is really small, then more is acceptable. Put a large (2″) steel washer against the seat for protection, then fill the remaining gap with plastic spacers, if possible. If not, then washers will work.
The other struts that are not painted are probably chromed steel and not aluminum. These should be bent individually so they just touch the seat and are the mounting tabs are parallel to the seat so there is no stress on them normally. When the kart flexes, these will pull and push on the bearing cassettes. These can easily be bent in a vise or with a mallet. Take your time, this is important.
KartLift Kart Stands
DeepSeat Kart Seats
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November 15-19, 2017
Las Vegas, Nevada
SKUSA SuperNationals 21
2018 Events TBA