The alcohol jet with a larger orifice must be fitted and air mixture must be reduced by fitting a restrictor tube or a slide valve. Fuel consumption is a lot higher when using meths in comparison to other fuels. Meths is on the other hand a good priming fuel since priming with meths does not soot as much as priming with other fuels. As with diesel, it is sometimes too crude to vaporize properly. The vaporized fuel is then forced trough the burner jet were it mixes with oxygen and the burns with a nice blue flame.
Output is controlled by adjusting the flow of vaporized fuel that is forced through the burner jet.
The cleaning needle moves like a rack when turning the spindle. When the spindle is turned to a full left, the cleaning needle clears the burner jet orifice. As the spindle is turned to the right again, the cleaning needle is retracted into the burner house. The cleaning needle arrangement on Optimus stoves is a prime feature. The risk of having unpleasant shutdowns when using the stove is reduced dramatically.