Put boards under the chassis and sit down with the seat and slide it around and tilt until you find a good spot. Then mark the seat struts with a sharpy and drill. Then put it on the scales and check for 50-50 side to side and 45-55 front to back.
FAA certified jet engine and aircraft technician,
Nicholson Speedway class champion 2001,
Yamaha KT100 Service Center,
41 years karting experience