Read the reply from Venice Motorbikes again.
Vibrations are going to happen with a single cylinder two stroke engine. It's just a fact of life, like death and taxes. You can not eliminate them. Trying to isolate them to the engine and not the bike frame will result in premature fastener failure at the engine mounts. Don't be fooled by those who will try to compare our bikes with Harleys and Hondas and cars. It's not the same thing. Using any resilient material between the engine and the frame will not stop the vibrations which are inherent but will concentrate them into the engine and mounts.
Make sure you have full contact between the engine mounts and the bike frame, no gaps, and live with the buzzing in your hands, feet and butt. It's just the nature of the beast.
Tom