| Component | Specification |
|---|---|
| Engine Oil | HD 360 SAE 20W50 (2.85 L) |
| Tires (F/R) | F: 100/90-19 | R: 130/90-16 (MT90B16) |
| Tire Pressure | F: 30 psi | R: 36-40 psi |
| Battery | Y50-N18L-A |
| Spark Plug | HD 5R6A |
The Wind Tunnel Pioneer: A Historical Perspective
The Harley-Davidson FXRT Sport Glide represents a pivotal moment in American motorcycle engineering. It was the first Harley-Davidson motorcycle to undergo extensive aerodynamic testing at the Wichita State University wind tunnel. This scientific approach resulted in the iconic frame-mounted fairing with its distinctive circular headlight and clear lowers, which provided unprecedented stability and wind protection compared to the fork-mounted fairings of the era. Built on the legendary FXR chassis—often cited as the best-handling frame Harley-Davidson ever produced—the FXRT bridged the gap between raw cruising and high-speed touring.
Engineering Deep Dive: The FXR Chassis
At the heart of the FXRT is the rubber-mounted powertrain system. By isolating the engine from the frame via three rubber mounts and a system of stabilizers, Harley-Davidson engineers managed to eliminate the high-frequency vibrations that plagued earlier models. This allowed the use of the high-torque Evolution (and early Shovelhead) engines without sacrificing rider comfort over long distances. The stiff, triangulated frame design provided a level of cornering precision that remains respected by modern enthusiasts and custom builders today.
Maintenance Essentials
Lubrication System
Maintaining the FXRT requires strict adherence to oil specifications. The HD 360 SAE 20W50 is the recommended lubricant, with a capacity of 2.85 liters. Given the air-cooled nature of the Evolution engine, maintaining clean oil is critical for heat dissipation and the longevity of the hydraulic lifters. We recommend oil changes every 2,500 to 3,000 miles to prevent thermal breakdown.
Tires and Handling
The FXRT utilizes a 19-inch front and 16-inch rear wheel configuration. For optimal handling, the front 100/90-19 should be maintained at 30 psi (2.07 bar). The rear 130/90-16 (MT90B16) requires 36 psi (2.48 bar) for solo riding, but must be increased to 40 psi (2.76 bar) when utilizing the original ‘clamshell’ hard bags for touring or when carrying a passenger.
Electrical and Ignition
The electrical system relies on the Y50-N18L-A battery. Due to the age of these machines, ensuring clean ground connections and a healthy charging system is paramount. Ignition is handled by HD 5R6A spark plugs, which should be gapped according to factory service manual specifications to ensure efficient combustion and easy cold starts.
Editor’s Verdict
The FXRT Sport Glide is more than a vintage motorcycle; it is a masterclass in functional design. While its aesthetics were polarizing in the 1980s, its performance capabilities have made it a cult classic. For the modern collector or rider, maintaining the FXRT’s technical integrity is essential to preserving one of the finest handling platforms in the history of the Motor Company.