| Component | Specification |
|---|---|
| Engine | Milwaukee-Eight 107 CUI (1746cc) |
| Oil Type | SAE 20W50 Harley-Davidson 360 |
| Oil Capacity | 4.3 Liters (4.5 US Quarts) |
| Front Tire | 130/90B16 (36 psi / 2.5 bar) |
| Rear Tire | 140/90B16 (40 psi / 2.8 bar) |
| Spark Plug | HD 60100003 |
| Battery | 66000175 (AGM) |
Engineering Highlight: The Hidden Evolution
A unique engineering milestone for the FLDE Softail Deluxe (2018-2020) was the departure from the traditional “counter-balanced” Twin Cam B engine to the rigid-mounted Milwaukee-Eight 107. While the Deluxe retains its nostalgic 1950s aesthetic, the 2018 redesign introduced a high-stiffness carbon steel tubular frame that is 34% stiffer than its predecessor. This chassis overhaul, combined with the hidden under-seat monoshock replacing the old dual-shocks under the frame, transformed the Deluxe from a vibration-heavy cruiser into a precision-handling machine without losing its classic ‘hardtail’ silhouette.
Technical Review: Milwaukee-Eight 107 Performance
The heart of the FLDE is the Milwaukee-Eight 107, featuring four-valve cylinder heads and dual spark plugs per cylinder. This configuration provides a significant increase in volumetric efficiency and thermal management over previous generations. The 107 CUI powerplant delivers approximately 109 ft-lb of torque at 3,000 RPM, offering a linear power band that is exceptionally smooth due to the internal dual counterbalancers. From a technical perspective, the integration of an oil-cooled exhaust valve system ensures that the engine maintains performance even under high thermal loads typical of heavy traffic or long-distance touring.
Maintenance Essentials
Maintaining the FLDE requires precision, particularly regarding the lubrication system and electrical health. The Milwaukee-Eight engine utilizes a dry-sump lubrication system; ensure the bike is at operating temperature before checking oil levels to avoid overfilling.
- Lubrication: Use only high-quality SAE 20W50. The 4.3L capacity covers the engine, but remember to inspect the primary chaincase and transmission fluids separately during major intervals.
- Ignition: The HD 60100003 spark plugs are critical for the dual-fire ignition system. Gap checks should be performed every 5,000 miles to ensure optimal combustion.
- Tires: The FLDE runs on 16-inch laced wheels. Maintaining the 36 psi (front) and 40 psi (rear) pressure is vital for preventing ‘cupping’ on the whitewall tires and ensuring the stability of the heavier Softail chassis.
Frequently Asked Questions
How often should I change the oil on my Softail Deluxe?
Harley-Davidson recommends an oil service every 5,000 miles (8,000 km). However, for riders in high-heat environments, a 3,000-mile interval is preferred to preserve the Milwaukee-Eight’s valve train longevity.
Can I use synthetic oil in the FLDE 107?
Yes, H-D Screamin’ Eagle SYN3 Full Synthetic 20W50 is an excellent alternative to the standard 360 mineral oil, providing better protection at high temperatures and longer shear stability.
What is the benefit of the HD 66000175 battery?
This is an Absorbed Glass Mat (AGM) battery designed specifically for high-vibration environments. It offers a higher Cold Cranking Amp (CCA) rating than standard lead-acid batteries, which is necessary to turn over the high-compression 107 CUI cylinders.