do this.. get your self 2 cans of a good carb cleaner, and 2 stroke silencer packing...
tkae the pipe off, take silencer apart.. inspect packing is it oily?? and black or pink or white.. blast out the inside of the silencer with carb cleaner. and do the same to the front pipe... let it dry good, ( can flush it out with a hose if you want) re pack silencer reinstal and go riding