All the whistles, rattles,tapping sounds ,and general clatter, on my Rocket disappear when I put on my rather tight XL helmet and ride away , nearly 50 years of driving heavy vehicles and towing trailers has me noise tolerant ,you will know when something is wrong it will either stop or a con rod will come out the side of the crankcase,
Hi Alan and welcome. That rattle is old news to many on here and the other Rocket forums. If it goes away when warm, don't worry. It is a normal flaw that some engines have. If it never goes away, you might have a problem. Search Paint Can Rattle.
I had that of problem on my 2013. Started at about 8000 miles and got worse. At 14600 miles it was so pronounced I couldn't ignore it anymore. Worst when cold but mostly gone when warmed up. It was still there When warmed up but almost inaudible. From Just off idle to about 1500 rpms. It was coming from the center of the engine in line with middle cylinder and low in the block. Required engine rebuild to fix it.