I have a stock 2004 GS500F with 18000 miles on it. I have owned it since it was new on the showroom floor. Today I was going to tighten up the chain and noticed the back side of the front fender is melted it is not contacting anything. Any ideas on what may have caused this. Bike seems to be running fine have been riding it to work and home (100 Miles total) 4-5 days a week for the past month or so. I did have to tear the carbs down and clean them before the riding season but thats all I have had to do other than regular PM. Thanks for any suggestions.
(http://i2.photobucket.com/albums/y1/wlpitbull/IMAG1034.jpg)
Mine looks like this too, only not as bad. I only have 5k miles.
I wonder if attaching something to the underside of the fender might help. To act as a heat sink? Or mount some kind of metal heat shield to block heat from the pipes.
Bad repaint, extended low speed riding or parked idling (without enough air moving around the cooling fins) or a lean AFR that overheats the pipes to read hot ... just some of the common reasons for what you are experiencing.
How do your spark plugs look?
-Jessie