Well then, we've narrowed the noise down to the electric start. The starter itself has no parts that could possibly produce this noise, but it is attached to the crank shaft on the left side of the engine via a chain. When chains go loose they have a tendency to slap things, like your stator cover.
If you want to explore, I would pull off the stator cover and see if the chain is loose or if the guide is worn or missing. If you take the side cover off the engine there is a chance you will need a new gasket, however.