40:1 or 30:1

dont be fooled into these ultra synthetic blends that have you mixing at 50-1 or higher ,less oil always equals more friction ,friction wears parts causes heat and robs an engine of over 30% of its power potential ,id recommend a clean burning premix that contains castor ,castor is probably the only oil tha t legitmatly makes power it has a higher BTU rating than gasoline when its bunred ,the full synthetics have a very high flashpoint and dont burn all that well at lower rpms that means unburnt goo in your case that loads up the dome and gums up ports ,seens it happen a million times with amsoil dominator ,id recommend 32-1 or 28-1 of Klotz supertechnaplate or castor 927 is really good too but burns a tad dirty on play gas motors