Chances are like ILENGINE said The spark arrester needs to be cleaned. It's located on the side of the muffler and you'll have to remove the cover so you can get to the muffler. There's a small plate on the side of the muffler, remove the screws, it's just a screen under the plate that needs the carbon build up cleaned. Clean the screen with a small wire brush and reassemble. Shouldn't be a problem.