Not starting now

My grandson has an Outlaw 50, that has been running pretty decent, until today.
He's 7, and figured out that riding off a ramp is lots of fun.
Anyway, he had jumped the ramp (only like 12" high) maybe 5 or 6 times. He heads down the driveway to get up some speed, and when he turns, the engine dies.
We pull it back to the house and I check and there's plenty of gas in the tank. I pull the spark plug and there is a good spark.
I give it a squirt of starting fluid, and it still will not fire.
Anyone have an idea where I should look next?
I've checked the electrical connections, and all seem good and tight.
Thanks for your help.

check your compression

Compression is just fine. No, I didn't screw a gauge into the plug hole, but I wasn't able to hold my finger over the hole while the engine cranked.

see if the carb is getting gas even though tank has fuel. shutoffs are not that reliable. disconnect fuel line from carb and turn on fuel using a catch can and see if it flows. if it does then the carb probably needs a thorough cleaning.