Building off what Scott said, you really shouldn’t be taking your kart out around public roads. Not only is it dangerous and not at all legal, but going at such low speeds probably overheated your clutch, which isn’t good for it either.
For reference, the clutch engages up until about 25-30 MPH, gearing dependent. This means that, unless you’re breaking the speed limit driving around your neighborhood in a go-kart, you’re slipping your clutch the entire time you’re on the throttle. That will generate a lot of heat, which can burn up/lock the clutch eventually.
I agree with Scott’s guesses though. You probably need new fuel lines, fuel pump, and zip tie the any fuel line connections. You’ll want a chain guard for your clutch, and the exhaust wrap may have oil or something on it that, but it isn’t supposed to be smoking as far as I’m aware.