Thaloc You could use blue-job (thought it was a joke), blue buster, or blue-away. i think you could find them at certain auto-parts stores.
06xb9r Lean causes heat which makes the pipes blue.
Almost every motorcycle will have this blue for a few inches, if it's severe this is an indication of an out of tune engine. Maybe running the wrong type of oil, or etc.
Hope I could help.