That's cool!
I've been helping my grandson build a go kart. We started out with a riding mower, built a frame, and moved everything we could use from the mower to the frame.
We got it running a month or so ago, but have been having drive belt issues. We finally got that under control and he was out beating paths around the yard. Around the 15th lap or so, he blew up the motor. Sorry, no video. I took the motor apart yesterday, melted down the rod and stuck it to the crank. Got everything apart and have most of the aluminum off the crank. I think we can get away with a rod, some rings, and a gasket set, but that will be a couple weeks away. We are funding challenged until after holiday at least.
I have located another running motor, I have located parts to fix this motor, and I have a parts motor that either needs rebuilt, or I can hijack the parts for the current motor, but any way we go is about the same money. So much for a cheap go kart.

At least it looks like the mini hot rod you built will have a line of users if your grandson out grows it. Gene