I can’t fault any one’s suggestions and you seem to have done all the right stuff, yet you still have a problem. You might want to put the kart on the ground and start loosening all the nuts and bolts in the steering, starting with the upper steering shaft support and work you way down. Please don’t offended, but I’m going to ask the dumbest question ever. Are the tires aired all the way up?
Hope you find the answer soon.
LAD Specialties customer / tony kart / rotax / kt100