As far as we know Sig never flew a prototype with a gas engine, electric only.
Given the weight these planes are ending up and the amount of weight needed up front to balance it, and the fact that one member here says the plane needed every bit of power from a 100cc to get off the ground, I really don't think that the plane would fly with Sig's recommended engine size..50-60cc.
Mine, with a Saito 90cc 3 cyl at 56-58 lbs showed absolutely no inclination to fly.
I think all of us on these forums have built the plane "by the book" and it's turning out to be a bit of a dud.
We'll have to wait and see what Sig's "structural update" is going to be....perhaps wing struts?