My 2005 yamaha 150xtr started running rough at idle. It stalls soon after putting it in gear. After starting it cold, I imediately pulled the cover to take a look and found exhaust smoke inside the engine area. As the motor warmed up, the idle seemed to return to normal but as soon as I replace the cover, the idle drops. It appears I'm getting exhaust up in the engine area depriving it of oxygen. It runs fine each time I remove the cover. The cover is not pinching fuel lines or interfering with anything else. Where can this be coming from? Thanks, Flash51.
