After writing the above post I fired the bike pack up and was checking things out with a flashlight. When the Pssst was happening I could see a burst of air/vapor popping out the left side carb inlet ( around the rubber) sure enough the clamp was loose. I tightened it all the way down but the clamp/band you can still rotate so guess it streched a bit too much. Figure a new clamp should take care of it. That's a relief.....
