One our engines hasn't sounded as crisp lately but I honestly thought it was me just looking for problems. I'm sure you have call teen there, if you finish in the back half you think it's something when usually it's driver. Last weekend before packing up ibran both our kart to get them warm because it had rained. I noticed on one you could see fuel/ air mixture blowing put the carb when reving it on tfdcstandcwith no air filter. I swapped carbs from one tobtge other with no change. (Other than theslidecand needle which is on position 3). Has anyone seen this on a 206? I assume it's an intake valve not sealing? The week before I had pulled the head and leak checked the valves, no leaks. Did a light lapping anyways just for fun and leak checked. Just for bubbles when blowing into. I will obviously check last again. It's possible I messed up.