ORIGINAL: hamaoki
That doesn't answer my question. I am asking about the piston rings and cylinder. I understand about the bushed bearings on the con rod and the cooling effects of the oil. I am curious about the lubrication required by the piston, rings and the cylinder.
The piston ring and liner will be OK at 50:1. Ken Lambert at Lamberts RC and Keith Baker at BME have converted SuperTigre 90's to needle bearing rods and they are fine at 50:1.
The bushing rods are the only thing that need the extra oil although with straight gasoline I have cut that down to 16:1 which is about 6.2%. I have been planning to cut it back further to 20:1 but it is running so good I hate to mess with it. My current project that I am refering to is a SuperTigre 51 on spark ignition.
Guys I hated to talk about sparkers on your gas/glow thread but I felt it would help him understand where my answer was coming from.