If I just wanted to replace the stock air cleaner, do I have to do anything else with the engine?

 

Might want to consider getting a fuel manager. Not absolutely necessary, but recommended. FuelMoto would be the place to go.

 

If you are thinking of getting a high-fllow air cleaner you definetly need to get a fuel manager otherwise you will run way lean, not good. I am running an SE air cleaner with a PCV, runs like a champ.

 

Stock pipes with Big Breather = No


Free Flow pipes and Big Breather = Yes


Free Flow pipes and stock Breather = No

 

Replace it with what? Help us here.

 

On my 07 heritage I installed a big sucker, xieds and cycle shack slip ons .it made a big diff. But you will get a million opinions

 

Is your 04 Heritage carbed or EFI?

If it is carbed, for it to run its' best you will need to do a bit of carb adjustment.

If it is EFI, you will want to use some sort of fuel management. The newer bikes will adjust for just an air cleaner, but on the 04 EFI bikes, the ECM is not as good at adjusting for the addition of a free flowing air cleaner.

Here's a good overview of the popular methods for EFI tuning-

https://www.hdforums.com/forum/ignit...uning-etc.html

 

I diff recommend the real K&N filter replacement over the MoCo K&N Paper made one....

 

Why?
And what is a "MoCo K&N Paper made" filter? Are you referring to Harley's cleanable performance filter which is not oiled?