would it be too weakits pretty thick but i dont know
listen pal if you have spare copper piping, you should weigh it in at a scrap yard - the price of copper has gone up three times in the last year if you have enough you could buy a proper go kart
Sure, if you want to be the first guy in the world to die in a copper go kart.
Wouldn't you be better off using the copper for scrap. I understand that scrapyards are paying a lot of money for copper. Get the money and make your cart out of something stronger, like steel.