Not a lot of information but I assume you're asking about some noise in the top end of your engine on your Heritage.
A Harley-Davidson engine is of an older design being that the valves are pushrod operated. It is not an overhead cam design like a lot of other bikes that try to look like Harleys. Harley has decided to stick with this design for as long as they can because it lends itself to what most Harley riders are looking for in their bikes, the traditional look lines and sound of the older motorcycles.
As such, there are a lot of components in the top end that must have some "running clearance" in order to operate. Push rods, rocker arms, rocker arm bushings, and such. A slight clatter or tapping noise in not uncommon. Now, it the noise if loud enough to make people turn their heads when you start the bike, you may have a problem. Usually a serious problem in the top end of the engine results in a poorly running engine as well.
You engine is equipped with hydraulic tappets. As the engine runs and things start to expand, the tappets are "pumped up" with oil to maintain a "zero clearance" in the valve train. If you have a tappet gone bad, it will make a loud erratic tapping noise that is sometimes accompanied by a bad running engine. You could have lost a roller on the end of a tappet as well. The Twin Cam engine was designed to help remedy the problem with the valve train geometry in the Evolution and earlier engines. It did straighten the pushrods up a bit but I still think it's possible to lose a tappet roller. If the noise is this loud, you will have to pull the tappet blocks and inspect the tappets to see if you have lost a roller.
Good Luck
Steve
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