Drehzahlmesser?

I understand that:

the speed meter determines the speed from time and number of ignition sparks. some two clocks have two cylinders. they always have two sparks per turn. single cylinder (for a motor saw the given) probably has only one spark per revolution.
in four-clockers it is a spark per two revolutions, (but, zb at the citroen 2cv, which is invented, both cylinders have always ignited, i.e. one even when it was in the output clock. was made to save a distributor, but also meant higher wear among the interrupters and spark plugs).
in a two-stroke one, however, I do not think it is sensible to ignite when it just sucks. That’s what’s going on…

but if there is another explanation, I am uncertain. If necessary, you can try out what it displays in which setting. that a chain saw does not make 10,000 turns, should be clear and in the performance indication, at which speed you work, you can estimate that.