I recently purchased an 02 Fat boy. Originally 88 Cu. In. total mileage is 28,322 and about 15,000 miles the upper end was worked with larger I believe he said 98 Cu. In. cylinders and Keith Black flat top pistons. Heads were worked and polished and Andrews cams were installed. Carb was changed to 40 mm and jetted and tuned. It has a noise in the bottom half I hear at idle. Any throttle and it goes away. Only hear it at idle speed. Runs great with excellent response. Anyone with experience on this engine have ideas as to what the noise is? Thanks in advance for your help.
Fat boy rider.

I had a similar situation: my problem was a worn primary tension adjuster.

That could be almost anything from a rod knock to a exhaust leak? It could also be normal for your engine. Since you had a lot of work done to it. I hear knocks and sounds at idle on mine too, but there is nothing wrong with it. Is it consistent? For example like you would hear a clock tic?

Go to your local Harbor Freight store and get yourself one of those engine stethoscope and find out exactly where the noise is coming from this will help you to find the cause. This tool is only a few dollars and will help you find out a lot about what is going on in your engine, transmission or primary.

Did you ever get around to finding out what was wrong?