| Component | Specification |
|---|---|
| Engine | Twin Cam 88 (Fuel Injected) |
| Oil Type/Volume | SAE 20W50 / 2.37 L (2.5 qts) |
| Front Tire | 100/90-19 57H |
| Rear Tire | 160/70B17 73V |
| Tire Pressure (F/R) | 30 psi / 36-40 psi |
| Battery | 65989-97C |
| Spark Plugs | HD-6R12 |
The 2006 FXDBI Street Bob holds a significant place in Milwaukee history as the first production model to embody the “Dark Custom” aesthetic directly from the factory. More importantly, from an engineering perspective, it served as the launch platform for the major Dyna chassis overhaul. This 2006 model year introduced the 49mm front forks and the first-ever 6-speed Cruise Drive transmission to the Dyna family, addressing long-standing rider requests for better high-speed stability and lower cruising RPMs.
Technical Maintenance Analysis
Lubrication System
The FXDBI utilizes the Twin Cam 88 engine, requiring 2.37 Liters of SAE 20W50 motor oil. At MotoSpecsLab, we recommend synthetic fluids for better thermal management, especially considering the air-cooled nature of the V-Twin. Ensure the oil level is checked when the engine is at operating temperature, with the motorcycle resting on its sidestand.
Chassis & Tires
The 2006 redesign moved the Street Bob to a 17-inch rear wheel, a departure from the traditional 16-inch setups of previous Dynas. The 160/70B17 73V rear tire provides a wider contact patch for improved grip. Maintaining correct pressure is vital for handling: 30 psi (2.07 bar) for the front and 36 psi (2.48 bar) for the rear. If riding two-up, the rear pressure must be increased to 40 psi (2.76 bar) to prevent sidewall overheating.
Electrical & Ignition
The FXDBI relies on the 65989-97C battery, which provides the high cold-cranking amps (CCA) required to turn over the high-compression V-twin. For ignition, the HD-6R12 spark plugs are standard. We recommend checking the gap (.038-.043 in) every 5,000 miles to ensure optimal fuel injection efficiency.
Editorial Review: The MotoSpecsLab Verdict
The 2006 FXDBI is a “mechanic’s favorite” for its transitional engineering. It offers the classic Twin Cam 88 feel but benefits from the modern 6-speed gearbox and the beefier 49mm front end that vastly improved front-end rigidity compared to the older 39mm units. While it was the first year of the new frame—which occasionally saw minor teething issues with the inner primary bearing—properly maintained units remain among the most reliable and customizable platforms in the Dyna lineage.