I thought maybe I would mention a couple things. When you increase the amount of oil in premix for a 2 stroke the jetting of the carb (or needle settings) may need to be opened up or you may have a lean running engine. The reason is that the oil displaces gas and when this is atomized in the carb the fuel-air charge going into the engine has less gas to burn. This can make the engine run leaner. Adding less oil actualy richens the mixture and can make the engine run rich. You have to cahnge the ratio pretty drasticly to see the effect but going from say 80-1 to 32-1 would have an effect. If you change your mixture from 50-1 to 25-1 and the engine runs hotter it's not from increased friction from oil it's from the engine running lean. All the oil does is lubricate and does not add to the combustion. More oil can can cause the rings to seal better leading to more power. For larger 2 stroke engines such as the ones used on dirt bikes 20-1 was found to be optimum with 32-1 to be the a good compromise. Our plane engines don't have the same load as these engines or operate at the 10k or 12k rpm where oil migration becomes an issue so the higher ratios work well. I've found that a lot of the problems with gas 2 stroke engines stems from bad gas more than anything. A hotter plug will not reduce carbon buildup. Good gas and oil with proper needle settings will. I always run the recomended plug heat range for the engine or maybe 1 cooler for the summer if it's hot. If I remember right, going up or down one heat range changes the exhaust temp 50F. Be careful if you go up in heat range or it could get expensive.