this^^^ Check your local club. No use to buy an obsolete Kart you can't race.
Raced 125 shifter 15 years ago and got into karting again last year. I really did not want too but my kid forced me ..
First year I was instructing him, at the end of the season he was faster with 2 secs a lap. I blame it on the 100 lbs weight difference...
It's an absolute blast. Great learning curve for the kid and nice people at our club. Got a toy hauler, sleep at the track...a race weekend feels like a mini holiday.