I'm no expert on Tomos but I thought they had oil injection. When you talk about messing up the mixture, do you mean gas/oil or fuel/air?
In any event, pull the plug and check the color, this will tell you best what is going on in the engine. Sometimes peds will smoke a lot from oil accumulated in the exhaust when it was not starting.
The chances of running with a bad piston are slim. This is a 2 cycle so smoke is not an indicator of leakage past the piston.