Just remembered: one of my 11 maxi-scooters was air/oil cooled---Daelim 125 in Korea, engine probably originally started as Honda design---worked well, never broke, daily wide open on my 10 mile ride home in the country. 65mph top speed. Had Puig windshield.
Daelim 250 scooter had complete Kymco engine and drive train. Kymco service so cheap in Korea at the time (about 10 years ago) it didn't pay to work on yourself---oil change/check/using their oil about $8---scooters used there commercial, so service done right.