I third Morini engine powered bikes,
Late 70s I bought a brand new Italavo moped with a Morini engine, basically I just popped out the two restrictor plugs in the air cleaner and it went 40mph. Did the same to my friends pacer, we had the fastest mopeds in the neighborhood Beating local Mobys Garrelli‘s, Tomos and Freespirits
Some Derbis if you remove the restrictor in the exhaust and Rejet the 12.12 they’ll go 40 easy
Safaris remove the plugs in the air cleaner and tune/remove supertrap exhaust disks and those bikes go 40 easy too.