explain "got a reproduction and didnt work" a little bit...
like...did it run? did you do anything, like try different jets, adjusting needles, or it simply didnt fit?
if it doesnt run...do some research into carbs. if YOU do some work, the carb will too...
if it doesnt fit, return it, rant and rave for your money back as the listing was incorrect.
there is no such thing as a genuine "yamaha" carb...nearly every manufacturer uses carbs made by someone else. more than likely a keihin or mikuni is the factory fitted one.
rather than order a pw50 specific carb, find out the carbs model number and order something at least similar... because you can basically adapt any carb to any engine as long as you put your mind to it, and dont expect a 32mm mikuni with spigot mount to fit onto something that takes a 16mm flange mount at most...
ie, a fiat 500(the original one, not the new remake) carb fits the lifan engines perfectly... huh? a car carb on a motorbike engine? yep
and NO new carb is EVER going to be a simple "drop in replacement"... you gotta rejet to suit your climatic conditions if you want decent performance... air temp, humidity, height above sealevel... never consistent from one place to another.