50cc Yamaha Vino bogs down at 10-20mph

[cuwee]

I was given a 2001 50cc Yamaha Vino recently (two-stroke), and am brand new to owning/working on a scooter (literally a week). When I got it, it had been sitting for a long time and would start with starter fluid, then immediately die. I removed the carburetor and took the whole thing apart to clean it. The entire inside was corroded, and I ended up ordering a brand new replacement on eBay (it was the only matching one I could find).

I installed the new carb today, and put in new oil and gas. It starts up immediately, and idles great. I can even ride it around the block with no issues until I accelerate up to somewhere between 10-20 mph. Then it bogs down. If I let off the throttle right away it keeps running and I can keep going at a lower speed. If I keep the throttle on it dies.

It has a new spark plug, and I've tried fine-tuning the throttle stop screw on the carburetor. The current position is the best one I've found, it starts up immediately, idles nicely, and runs smoothly up to the 10-20mph speed. I've confirmed the fuel hose and vacuum hose are in good condition and not blocked. Nothing I've tried has allowed me to run at full speed.

I have no experience with engines other than what I've taught myself the last week trying to get this to run, so there are probably some obvious solutions I just don't know to try. Any help is appreciated!