Speed’s Secrets February 2007

Deep Breathing!

Reduced to the basics, a V-twin engine is just a giant air pump. Needless to say the easier that pump can breathe, the more air it can take in and expel, so the better it will perform. We’re not talking just all-out horsepower and torque numbers, either. A free-breathing engine responds to the throttle better, runs crisper throughout the powerband, and should even deliver better fuel mileage. A free-flow muffler can take care of the back end of this breathing equation, and an equally free-flowing air filter on the intake gets it all started.

The guys at Speed’s Performance Plus travel the country tuning and maintaining literally thousands of motorcycles every year. They see it all. And all of that experience has distilled into the “Speedy Flow” air filter kit, a high-flow package answering every question and concern raised by what they’ve seen or fixed. The Speedy Flow air cleaner assembly retains the OE cover, accepts most aftermarket covers and, combined with a good exhaust and re-jetting/re-mapping, delivers up to a 15-percent boost in performance. Its billet backing plate has a unique internal breathing system, and with optional spacers accepts Speed’s One-Way Crank Vents that, themselves, are good for up 3 to 5 MPG and easier running. The kit has high-temperature Viton O-rings to eliminate pesky oil leaks, and there are locking tabs to keep all mounting bolts from working loose. The Speedy Flow uses a larger, deeper Speed’s filter element, too. It’s 5⁄8-inch wider than most other filters, so it’s nicely sized for the new TC96 or 100-inch engines as well as the TC88.

That Speed’s filter element should last the life of the bike, too, because it’s washable and reusable. Unlike foam or paper filter medium, the Speed’s element uses multiple layers of pleated cotton gauze sandwiched between two layers of coated aluminum wire mesh. The design also helps increase the airflow. And the filter is serviceable. When the aluminum mesh is no longer distinguishable from the pleated cotton it’s time for a cleaning and re-oiling. Never use compressed air to clean these filters, though. Tap the filter to dislodge any loose debris and liberally spray on a filter cleaner, saturating both the outside and inside (filter service kits are available at all bike shops and parts stores). Allow the cleaner to work for a while and then rinse the element clean under running water. Let it air-dry before re-oiling (special filter oil is included in the service kit). As with all serviceable filters, applying too much oil is as bad as none at all. Apply a little at a time, giving it time to soak in. The goal is to attain the same deep-red color the filter had when it was new; best way to get there is in stages.

Deep breathing is the key to a healthy, strong-running engine. And for a Harley engine that means using a high-flow air filter. You can exhale now.

Article reprinted from Iron Works Magazine, Feb 2007

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