Thanks for the reply's!
Keihin says ask a distributor, distributor says ask Keihin. Keihin site does not list any carbs with a PA prefix.
Hobbit, the adapter is intake manifold to carb so it might have had a Mikuni at one time. It is not a CV carb but butterfly type carb. Service manual only shows Keihin.
Thanks again for the replies!
I've spent a little more time looking over this scoot, it's been worked over by previous owners. I discovered the electronic ignition has been replaced with points. I just bought it two months ago I this is the first I've spent any time wrenching on it.