Our engines that we call Diesel really are not so, but are actually compression ignition engines. The term Diesel refers to the original patents and design of Rudolf Diesel (1897-1898) for an internal combustion engine.

When air is compressed sharply, as in the compression up-stroke of the engine, heat is generated. We have seen this effect in a bicycle pump and in science lab when we were tads.

In a typical Diesel engine such as in Trucks, Tractors etc, this compression heat generated can be as much as 5-600 deg F or more which is sufficient to ignite the vaporized kerosene or Diesel fuel that is time injected into the cumbustion chamber to initiate the power cycle.

Our little engines do not have a fuel timing or injection pump so we mix fuel, Ether, Kerosene, lubricant & other ignition additives and operate the engine as a simple 2 stroke engine. The engine draws this fuel/air mix into the crankcase whereby it is compressed during the downstroke and passed to the combustion chamber through the bypass ports. All this is timed by the piston top or skirt or by a rotary or reed valve depending on the design of the engine.

On compression the heat generated is insufficient, in these little engines, to ignite vaporized kerosene. Therefore the Ether in the mix (Ether has a much lower flash point than Kerosene) must initiate combustion which it does nicely. Ether, in initiating combustion, fires the Kerosene and so it goes. This is why Ether is essential to the process and must be storage protected to minimize evaporation.

The variable compression feature is used to raise, or lower, compression sufficiently to generate enough heat and used thereafter to vary the ignition timing depending on the load (prop size) of the engine, similar to the timing effect of a gasolene ignition engine. Hope this is helpful...sorry for the lecture.