G'day folks,
I agree with CyberJack here; it's to do with the different carby/fuel delivery systems.
As well as the density/specific gravity change between the mixes, the fluid flow characteristics [surface tension, viscosity] will also differ, as will the vapourisation efficiency.
24:1 is of course leaner in terms of oil content, so it might well better suit the more primitive 'suction carby'.
In any case, it will work better with modern two-stroke oils than it ever did back in the day. Even so, I don't think it's advisable to change the mix ratio too much, as that will affect the fuel/air ratio that the carby delivers.
