I was given a 2004-2006 Birel tag chassis. Bent frame and bent up front spindle yoke. But free! But 250$ to fix er up. My lo206 turned into a world formula 12 to 1 Dyno 310 cam. 8500 rpm sprint kart. I trimmed the birels weight to 160#. Most of the modern push back bumper karts weigh around 170-175#. Most of the karts in my area r otk, cosmic karts. They call them the noodle. I had a friend drive my kart a few times and I’ve never seen the birel pick up the inside rear wheel. I’ve tried go proing the inside rear wheel. Noda to lifting the inside rear tire.this year a 2000 $ cosmic came along for a grand. So I jumped and bought it. So super stiff to super soft. Chassis.the general consensus is it should b 3 tenghts quicker. I put everything of the birel as used last September. Tires,seat, body to lighten it. So I’m excited to see if a 20 year newer kart makes a diff. My engine will have 1 point more compression. Also waiting 356 dyno cam and valve springs. It will b interesting to see if I can learn to control the inside rear wheel lifting. 