Thanks for the tips Miguel and everyone else who responded. That is good to know.
My Bianchi Snark went from a top speed of about 27 mph on a straight away to around 32 mph. The 14/12 jet is a #50. I couldn't read the old jet #.
I love my Snark also. It's a blue '76 Standard. It's peppy and very easy to maintain, as opposed to my '77 Motobecane which requires oodles of tinkering to keep running. I wouldn't sell it for the world. That's the problem with me and mopeds, I buy them and just can't bring myself to part with them once I fix them up.