i run at all my green 2 stroke monsters 40 : 1 mix (only motul)
i tried in the first 32 : 1 and came more oil than smoke out of exhaust. (this rich mix i only use at new or complete rebuilded engines. 1 or 2 tank fillings than back to 40 : 1.)
some guys ride 50 : 1 . ktm says in manual book up to 60 : 1 for 250cc -380cc motors. maico and zabel (sidecar motors based on maico 500) says up to 100 : 1 mix for the 500cc - 700cc motors with their special oil ..
but i think i´m on the safe side with 40 : 1 mix. engine runs clear. piston look always like fresh installed, when i pull cylinder.
its a simple rule: less oil in the mix = more effective power from the gas. but never take too lean mix or cheap bad oil, that will risking engine damage that one!!