What is the fuel to oil ratio on a Yamaha kt100?

Anywhere from 16:1 (8 oz. of oil per gallon) to 20:1 (6.4 oz. per gallon), the lower ratiOS are better when using castor oil blends; with synthetics like Redline two stroke racing oil, 18 or 20:1 works well. 7 oz. per gallon (18 oz. per gallon) has worked for me for years using Redline.