I am double posting this so I can get feedback from the general public and the Yamaha crowd. Sorry if you see it in the Jetting/carb forum too. Here is the deal I am out of ideas, so I came here to see if if there is anything I am missing before I start mass tear down. Problem: out of the blue, nothing has changed my YZ has started fowling plugs at an insane rate. I fowled one yesterday playing in the pasture and 2 today in the parking area headed to the trail. I have not changed anything on the bike and it usually runs perfect. It will not idle at all, if you let go of the throttle it goes straight to dead. I also have an increased amount of smoke from the exhaust at idle and under power. Machine Specs: 1996 YZ250 recent top end (20 trails hours maybe) has great compression PC pipe and silencer Carbon fiber reeds 175 main 42 pilot NGK BR8ES plug 32:1 ratio Things I have tried: new plug ( stock and one heat range warmer) Complete tear down and cleaning of carb (btw carb cleaner burns like a when you get it in your eye.) cleaned the air filter reeds look good adjusted mixture screw attempted to adjust idle speed, but has no effect. I am open to suggestions, do I need to look toward case seals? Could a tank of bad gas cause all of this? Anything helps and thanks in advance.