I will put here some bits and pieces that may be of interest.

Sine wave shapes, I apologise for the poor quality of the pictures however you should be able to get the general idea.

The shapes are from two different generators, one is a cheap two stroke and the other is a more expensive four stroke powered by a Robin engine.

Also check out the 240Volt output waveform from the standard UPS used by many businesses for computer fail safe power. For those who worried about the wave shape this was certainly an eye opener for me. I had the unit to change the back up battery for a new one for a customer.

I did a short test the other day and loaded the GME 750Watt gennie up with 700 watts and let it go for a hour, the whole thing got a bit hot however the output never changed. My GME is rated at 650 watts continuous and 750 watts max.