ORIGINAL: gubbs3
A two-stroke engine can easily run backwards, the only difference is the timing of the engine is retarded rather than advanced. This means that it will make virtually no power and as soon as you hit the gas it will die.
In spark ignition engines yes, but in glow engines the timing is automatic therefore an engine can run backwards with the correct timing..
The reason they dont put out much power is because the crank port or rotary valve is WAY off timing when engines are running backwards.