WR, the two 125s I have are 7,200 rpm engines no matter what you do. The gasoline one turns a 15x8 two blade at 7,200 and Diesel one turns a 15x8 three blade at 7,200 but with a much smaller carb. I believe that the stock carb was too big even for gasoline operation, the only thing the last 30% of throttle opening accomplished was to let the carb throb louder with no increase in rpm.