The filler cap measurements were correct for the type of Two-Stroke oil available at the time,they were,Shell 2T Two-Stroke Oil,BP Zoom or Energol Two-Stroke Oil,Regent Motor oil 2T,other oils...Castrol Two Stroke Oil & Castrol XXL,Esso Motor Oil and MobilMix TT all required a mix of (1:16) which is actually a 5 cap measure,because of technology new oils may require a different mix as they are fed by pump to the cylinder with the petrol and not mixed together prior to use,it should tell you on the bottle,but it MUST be 2 stroke oil as it mixes more freely,to much will only foul your plug to little could cause siezure.
Rich
December 2009