Clean A Harley Fatboy Air Filter

The air filter or cleaner, as described by Harley-Davidson, is an important part of the FLSTF Fat Boy’s air intake system. The stock air cleaner relies on a paper filter element to screen out harmful dirt and road debris that can clog the motorcycle’s carburetor and cause internal engine wear. Harley-Davidson recommends an inspection of the air cleaner at every 5,000-mile service interval. While the air cleaner is an item that eventually will need to be replaced, it can be cleaned and reused until the filter element begins to wear.


1. Remove the screw from the center of the air cleaner cover, located on the right side of the engine between the front and rear cylinders, using a T27 Torx driver. Pull the air cleaner cover away from the air cleaner.

2. Remove all three screws from the face of the air cleaner, using a T27 Torx driver. Grasp the air cleaner and pull it away from the air cleaner back plate and the engine.

3. Inspect the air cleaner’s paper filter element for obvious tears or holes. Replace the air cleaner if it is damaged in any way.

4. Soak the air cleaner in a tub filled with lukewarm water and a mild detergent. Use a gentle side-to-side motion, while the air cleaner is submersed, to dislodge dirt and debris from the filter element pleats. Remove the air cleaner from the tub periodically and hold it against a bright light to check the element’s cleanliness. The air cleaner is clean when you can see light through the element.

5. Remove the air cleaner from the tub and shake out excess water. Allow the air cleaner to air dry, or blow a low-pressure stream of compressed air through the inner face of the filter element until it is dry.

6. Push the air cleaner over the pair of breather tubes at the center of the air cleaner back plate. Reinstall the air filter screws and tighten them to 36 inch-pounds, using a torque wrench.

7. Inspect the air cleaner cover gasket for tears or signs of damage. Replace the gasket if it is damaged in any way. Reinstall the air cleaner cover and tighten the cover screw to 36 inch-pounds.