I have posted this once before with not much luck so I am trying again. I have a lowered 98 Fat Boy that is in very, good condition with 24,000 miles. When I shift into 4th gear I start to hear a chirping like noise start and again when I shift to 5th and then the noise is some what continuous. The odd thing is that it only happens when my wife is riding with me, and she is only 100 lbs. It is not a cyclic noise and it comes and goes but is present throughout the ride only when she is on. It sounds like it is coming from the front of the primary or shifter area and gets very loud. Once again any ideas.

 

Just throwing this out there for something to check. Have you checked the belt tension with you and the wife on the bike?

 

Start with the basics, Is your belt a little loose or rear tire/sprocket slightly misaligned?