| Feature | Specification |
|---|---|
| Production Years | 2006–2017 |
| Engine Oil | SAE 20W50 (2.8 L) |
| Front Tire | 100/90-19 57H |
| Rear Tire | 160/70-17 73V |
| Tire Pressure (F/R) | 2.1 bar / 2.5–2.8 bar |
| Battery | 65989-97D |
| Spark Plugs | HD 6R12 (Gap: 0.97–1.09 mm) |
Did you know? The 2006 Harley-Davidson FXDB Street Bob was the inaugural model for the “Dark Custom” movement, but more importantly, it was the first Dyna to introduce the 6-speed Cruise Drive transmission and the 49mm front forks, significantly increasing the torsional rigidity of the front end compared to its 39mm predecessors.
Engineering Overview
The FXDB Street Bob represents the essence of the Dyna family: a rubber-mounted V-Twin engine nestled in a chassis designed for raw feedback and customization. During its 2006–2017 run, the model transitioned from the Twin Cam 96ci to the high-output 103ci engine. This era of the Street Bob is characterized by its mid-mount controls, solo seat, and mini-ape hangers, making it a favorite for riders seeking a mechanical, visceral experience without modern electronic interference.
Maintenance Essentials
1. Lubrication System
To maintain the thermal stability of the air-cooled Twin Cam engine, MotoSpecsLab recommends SAE 20W50. The system capacity is 2.8 Liters. While Harley-Davidson 360 mineral oil is sufficient, the synthetic SYN3 is preferred for high-ambient temperature environments to prevent viscosity breakdown.
2. Tires and Contact Patch
The Street Bob utilizes a specific staggered setup. The front 19-inch wheel requires a 100/90-19 57H, while the rear 17-inch wheel takes a 160/70-17 73V. Maintaining correct pressure is critical for handling: 30 psi (2.1 bar) at the front and 36 psi (2.5 bar) at the rear for solo riders. Increase the rear to 40 psi (2.8 bar) when carrying a passenger.
3. Electrical and Ignition
The FXDB relies on the 65989-97D battery, which provides the high cold-cranking amps (CCA) necessary to turn over the large displacement V-twin. For the ignition system, use HD 6R12 spark plugs. It is vital to verify the gap is between 0.97 and 1.09 mm to ensure efficient combustion and prevent fouling.
The MotoSpecsLab Verdict
The Dyna Street Bob (FXDB) remains one of the most sought-after modern classics in the Harley-Davidson lineup. Its mechanical simplicity, combined with the robust 6-speed transmission, makes it a reliable platform for both long-distance touring and urban bobber builds. Regular adherence to the oil and tire specifications listed above is paramount to preserving the longevity of the Twin Cam drivetrain.
Frequently Asked Questions
What is the correct spark plug gap for the FXDB?
The gap should be set precisely between 0.97 and 1.09 mm using a wire-style feeler gauge.
Can I use a different battery?
While aftermarket options exist, they must meet or exceed the specifications of the OEM 65989-97D to handle the compression of the 96/103ci engines.