An aftermarket Harley air cleaner
Owners of Harley-Davidson motorcycles with Evolution or Twin Cam engines routinely make a few simple improvements to increase the performance of their bikes. The most basic improvements are usually called a “stage 1 upgrade,” and are designed to allow your motor to “breathe.” Stage 1 upgrades are very simple improvements that do not require you to tear your engine apart. These improvements typically include upgrading the air cleaner, installing an aftermarket exhaust system, and either rejetting the carburetor or remapping the electronic fuel injector control. The easiest of these improvements to accomplish is replacing the air cleaner.
1. Remove the outer cover. If you currently use a stock air cleaner cover, turn the hex bolt in the middle of the cover counterclockwise. Aftermarket air cleaner covers may have up to five bolts. After you remove the bolt or bolts, the outer cover pulls off easily. Set the cover and bolt onto a soft, clean surface.
2. Place clean shop rags over any chrome, like your exhaust heat shields, to protect those surfaces while you work.
3. Use a Torx key to loosen the four air cleaner element retention bolts on a stock air cleaner. The bolts will be in the four corners of a rectangular retention plate in the middle of the air cleaner element.
4. Pull the air cleaner element and retention plate about two inches away from the backing plate once the bolts are loosened. Unplug the two top breather tubes. Pull the whole assembly away from the backing plate, and set the complete assembly on a soft, clean surface.
5. Use a hex key or hex socket to loosen the two breather bolts at the top of stock backing plates. Loosen everything on a Harley by turning it counterclockwise. Remove the bolts and remove the backing plate. The throttle body will now be completely exposed.
6. Install the new backing plate by tightening the original breather bolts clockwise with a hex key or hex socket.
7. Use the original or replacement air cleaner element retention bolts to bolt the new air cleaner element to the new backing plate with hex or Torx key. The tool you use to install the new element will depend on the aftermarket model you buy. If appropriate, plug the breather tubes into the top of your new element.
8. Use the bolts included with your new air cleaner cover to bolt the cover to the air cleaner element.