Powerdynamo, wasted spark, why and is it harmfull?

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wasted spark, can this do harm to my engine?

Some of our two stroke system, notably for twins give sparks every 180 degrees crank movement. With this a cylinder also gets spark with the piston at bottom.
In our 4 stroke systems with impulse collection at crankshaft level there is something similar. There is spark every revolution and not only every second.

Such arrangements are not an invention of Powerdynamo. Many original systems work like this as this greatly simplifies the ignition setup and there is absolutely no harm in it.

Any  combustion engine, and a motorcycle engine is one, is an explosion engine. It is this (controlled) explosion within the cylinder that drives the piston downwards which is at the origin of engine power.

For an explosion you need 2 things: explosive material and ignition.
The explosive material here is the petrol/air mix. However, a mix of petrol and air alone is not really explosive yet. It needs to be in a certain mix (which the carburettor hopfully provided) and it should better be compressed. This is what happens when the piston goes upwards and the cylinder chamber is closed - what happens in combustion cycle. Near TDC it is met by our spark and explodes.

So far so good, what what happens now when there is also a - wasted - spark witch the 2 stroke piston near bottom or the 4 stroke piston in exhaust cycle?
virtually nothing, as
- there is no pressure in the cylinder - exhaust ports/valves would be open
- there is no fuel to burn in the cylinder, it just had been used
- whatever there might happen in terms of flame development would exit harmlessly  into the exhaust.

A you see there is no harm in this use of wasted sparks, but construction of the ignition is greatly simplified by it.