No stock 50cc scooter is going to go 50 mph. Not even close. I have modified 50cc pedal mopeds (Puch, Tomos) to do 50 mph, but they had very short lifespans. If you see a 50cc scooter doing 50 mph, it has been SERIOUSLY modified.
Also many states are now passing laws about where you can ride a 50cc unplated scooter. 35 years ago I put over 20,000 miles on a stock Puch MaxiSport, at 30 mph, on non interstate roads. I toured 4 states, and a good part on northern Mexico. I wouldn't even consider doing it now. The speed limit was 55 mph back then. No people drive 80 mph on 65 mph roads around here. You will need at least a 125cc scooter to ride where you want to safely and legally. I recommend either a Yamaha Zuma 125, or a Genuine Buddy 125. These are both top notch scooters. I'm getting ready to buy a Zuma 125 in a few days. I would consider a Buddy for sure, but the Genuine dealer does not take trade ins.
2002 Vulcan 750 (now being slowly reassembled) 2013 Royal Enfield B5
2001 XT225, 2009 Genuine Stella
1980 Puch moped