Modern Vespa

Hi! So I'm having issues trying to keep a 2007 Lx50 to stay idling. Keep
In mind that this scooter has been sitting since 2014. I've seen a few post that have been helpful but still haven't been able to fix my problem. So the first thing I did was to check the tank for any old fuel, it was bike dry. Then I replace the battery, a new spark plug, a carb clean, new fuel filter along with a new fuel and vent hoses, and a new air filter. It started up and would be fine when I gave it open throttle, but then after letting off the throttle and letting it just idle it would slowly just die off. That's when I noticed the gas that was pouring out of the air box. So I thought the float is the issue. I pulled the carb apart and noticed that the pilot jet was clogged as well. So I did a second carb clean, washed and re-lubricated the air filter, and adjusted the float height. In reinstalled the carb and again that seem to fix the gas pouring out of the air box, but again it still won't idle. I tried adjusting the idle screw but nothing. I even tried putting in a new carb and I'm still having the same issue. I'm able to give it wide open throttle and hold it there but the minute I let it idle and just slowly dies off.
Any help would be appreciated.
Thanks!

Welcome!

Is it possible the tank had some sediment or varnish that keep clogging up your idle jet?

Maybe you have a small leak in a fuel vacuum line, so it gets enough vac (fuel) when revving, but not at idle?

I will have to try a fuel flush and see what happens. I even put an inline fuel filter because I thought maybe that was the problem. But still nothing. I also don't see any evidence of fuel leaks anywhere. Is there a way to test if there's a leak?

Baby powder.

Baby powder?

Try to test somehow if the vacuum fuel petcock is working as it should. Is this what you refer to as "the fuel filter" that you changed? Because 50s do NOT use fuel filters per se. All the fuel filtering is done by the screen on the vacuum fuel petcock. If you're running an inline filter that might be what's causing the issue. Quadruple check all hoses for leaks and tightness. Check the rubber intake manifold is not leaking vacuum. Check the rectifier/stator and also check the ignition module.

Useful to detect where an oil/gas/any liquid comes from.

Clean the engine case or any mechanical part correctly, make sure any greasy oily spot is clean. Go for a quick ride and put baby powder with a brush on the different parts. The BP will stick to any surface that is oily/greasy or contaminated with gas and will show you where it comes from.

I had a lx50 4T and installed a inline fuel filter for a motorcycle when I was having problems.I had to remove it was to restricted also make sure the filter is in the right direction .Look for the arrow on the filter. You do not need a filter as the peacock has a screen on it thanks

Yep
Just sprinkle some baby powder on the engine and you'll find out where the leak is.

What year is it?

Read the original post.

It's a 2007.

It would be a lot easier to shoot if you put it on the center stand.

Replacing the carb goes a long way towards making me think this isn't a fuel issue. You replaced it with a proper carb, not a substitute? If it's a Chinese hack the problem could be literally anything.

You might have an intermittent spark situation going on that the flywheel is masking at high speeds.

Check to see that the spark plug is clean, and tightened, and that both sides of the ignition wire are clean and making good contact (spark plug and CDI).

Sorry

Don't sweat it.

Check the carb boot (intake) for cracks, any vacuum line you come across, the valve clearances, and fuel flow to the carb.

Juan, after reading I don't think he replaced the carb, just took it out and cleaned it twice.

Well, maybe, but that's not now I interpreted "I even tried putting in a new carb and I'm still having the same issue."