I have given well nuts a shot in mounting a two-stroke .91, using the diagram presented on one of the websites that you'd think knows their stuff. Nothin' but trouble. There are a couple other sources that recommend or incorporate well nuts for engine soft mount applications. These devices will become permanently involuted, as well as deform in other ways. If you have occasion to un-mount and re-mount your engine, they just don't stand up to the abuse. I had to cut out the rubber bits from my original set, because they were out of line with the mounting screws, and they would not withdraw from the front of the firewall, as the pretty pictures suggest they would. (One did, three had to be surgically removed.) Plus I have a knot in my arm from two hours of twisting my balldriver to get these things on and off. The more I try other (supposedly cheaper) soft mount methods, the more I like the Dubro mounts.

The only soft mounts I've found that work well are the Sullivan Dynamounts and the J-Tecs for large gas engines.