Havana Classic 50, anyone have any ideas?
 

My friend has a 50cc Havana classic. She road it until it ran out of gas and then let it sit for two weeks. When she tried to start it up again, it would idle, but would bog out as soon as she opened up the throttle. It seemed pretty clear it was fuel related, so I rebuilt the carbs and replaced the petcock in one sitting for her. I also removed the variator's speed regulator because I was already dirty and I figured why not. I put everything back together and now no gas is getting to the engine at all. If I spray some starting fluid directly into the intake boots it'll sputter, but otherwise when I try and start it, I wiggle the throttle and hold the starter button, and the engine just cranks flatly. It has spark, and I tested the petcock fuel and vacuum lines, they are solid. I took the carbs off twice after and re-inspected them, all pathways are unclogged, and I am sure the float is in the correct orientation. I should also note that when I first rebuilt them, they were not as dirty as I would have expected to begin with. I feel bad because I feel like I made the problem worse. I am already down the rabbit hole, though, so any thoughts on what it could be/what I did wrong would be helpful.

Running out of fuel rarely causes issues but....
Check the main jet for blockage. Compressed air preferred. Don't go jamming metal into the jet holes to clear them, that will cause other issues.
Did you check the spark plug? Make sure the gap looks good and nothing is stuck in the electrode.
If it ran good before being run outta gas those are the only 2 things I would check. If it ran cruddy before running outta gas I would also do a valve check just to make sure something else didn't rear its head at the same time. Seen it happen before.
Let us know if you figure it out and good luck!

I'm assuming this is a 50cc 4-stroke Lance scooter.

Did you try starting it with the gas cap open? If the bike was overfilled it could have filled up the evap canister and now there is no venting for the tank. A carb clean may be in order too but it should do more than sputter if you spray starter fluid into the intake.

All gy6 49cc engines come out of the factory with the valves too tight it will run for 10 to 50 miles then it just won't. I replaced over 15 carbs and did 5 complete rebuilds before I figured it out. Then it was never a problem again. It became part of the uncrating checklist at my store.

Another part of our checklist was to drill a 2mm hole in the gas cap so they vent. Just the first layer of the cap.