Engine reminds me of the liquid cooled Hewland AE75 750cc inverted three cylinder 77 bhp 2 stroke used in the ARV Super 2 two seater light plane developed by Richard Noble. That was lubed by 40:1 pre-mix.

Richard

2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone