OK TT Gurus! I posted a few times a couple of months ago about my plug fouling problem and got some great ideas to try but nothing worked. Heres the skinny! My bike is a 1998 WR 400 used as a dual sporter. It is fairly low mileage and in excellent, clean, well maintained condition. The bike ran fine until early this summer when it started fouling spark plugs at least each ride. It continued to get worse until it now fouls a plug after about 2 minutes of running. I have replaced all electronic components including the CDI, Stator, Ignition coil and plug cap, Unhooked the grey wire, tried it witht he stop switch and TPS unhooked. Still no difference. I went torough the carb with a fine tooth comb and dropped the needle all the way. Checked float height and even ran it without the air filter to be sure it was not causing too much restriction. No Change. It fouls a $3 plug after only a few minutes of operation. Yes the plugs are black but I cant get enough time on the engine to take a proper plug reading. I believe they are sooting up while in the start-up mode. It runs great with no black smoke until it fouls the plug a few minutes later. Some of you said re-jet the carb but, it ran flawlesly for 3 years and probably on the same plug and all of a sudden started this. My dealer is no help, Yamaha customer service has been no help. This bike is un-ridable. If anyone has any ideas please help. I would buy a new 450 if I could get this one to run long enough to trade it in.