A dry sump lubrication system uses a separate oil tank and either two oil pumps or a combined oil pump that performs both the function of a pump to supply oil under pressure to the engine components and a scavenge pump to return the used oil back to the tank. The scavenge pump should have a slightly greater capacity than the pressure pump to prevent oil accumulating in the engine.

I am not sure about the Harley but all the dry-sump motorcycles I have seen the oil can be seen returning into the tank as soon as the cap is removed. A good flow of returning oil is a sign of a healthy lubrication system.

As the oil in the tank will quickly become heated and expand and the returning oil might contain a few bubbles of gas the tank would generally be vented to prevent a pressure build-up.

The oil should not smell of fuel if the bike is used for normal purposes so the engine is thoroughly heated. Lots of cold starts and short journies could produce slight fuel odours in the oil tank. If the odours become strong it is likely to indicate a fuelling fault that should be investigated and rectified before an oil change.