Because he’s at 315 lbs and I would be over 400. He’s a good driver. I’m not so great. So I need something that’s faster so I can reel him in on the straights. Hopefully.
Maybe world formula? Or build out an animal a little?
Honestly, for something that’s just to chase your kid around. I’d just put more lead on his kart on practice days, and save yourself the headache.
(Especially for what should be a fun kart, you’d be spending way more effort to build something unique, just to not drive it that much, and have to deal with so many different parts if/when the fun kart breaks.)
That or throw a World Formula on it, and then just enjoy. Much easier, in my opinion.
Our local group runs a class with modified 420 preditor harbor freight motors. They race at 450 lb, have a field of 18-20 per race, make like 23-25hp, they are cheap and readily available and are faster than the Yamaha pipe class that I race.
Search for OVKA 420 for details.