| Specification | Data Detail |
|---|---|
| Engine Compatibility | Twin Cam 103 (2010-2016) / Milwaukee-Eight 107/114 (2017-Present) |
| Engine Oil | SAE 20W50 HD 360 / SYN3 15W-50 (3.8 Liters) |
| Tire Dimensions | F: 130/80B17 65H | R: 180/65B16 81H |
| Operating Pressure | Front: 36 psi (2.5 bar) | Rear: 42 psi (2.9 bar) |
| Battery Reference | 66010-97E |
| Spark Plug Type | Twin Cam: 6R12 | Milwaukee-Eight: 60100003 |
Engineering Highlight: The FLHTK series achieved a significant engineering milestone in 2014 with the introduction of Project RUSHMORE. This marked the debut of the ‘Twin-Cooled’ High Output Twin Cam 103 engine, which utilized liquid-cooled cylinder heads to manage heat dissipation around the exhaust valves—the first major departure from traditional air-cooling in the core touring lineup’s history.
Technical Overview: The Grand American Touring Benchmark
The FLHTK Ultra Limited represents the pinnacle of Harley-Davidson’s touring architecture. From 2010 to 2016, the model was powered by the Twin Cam 103, transitioning to the Milwaukee-Eight (M8) platform in 2017. The M8 engine introduced a four-valve-per-cylinder head design, offering improved thermal management and a significant increase in torque delivery. The FLHTKL (Low) variant, produced between 2015 and 2019, was specifically engineered with a lower center of gravity, featuring a 25.6-inch seat height and pulled-back handlebars to accommodate riders with a shorter inseam.
Maintenance Guide & Fluid Dynamics
For optimal performance, MotoSpecsLab recommends adhering to the 5,000-mile (8,000 km) service interval. The lubrication system requires 3.8 liters of oil. While SAE 20W50 HD 360 is the standard, high-performance touring in extreme heat benefits significantly from the SYN3 15W-50 synthetic alternative, which offers superior shear stability.
Chassis and Contact Patch
The FLHTK utilizes a heavy-duty touring frame. Tire maintenance is critical given the bike’s wet weight exceeding 900 lbs. Ensure the 130/80B17 front and 180/65B16 rear tires are maintained at 36 psi and 42 psi respectively. Under-inflation leads to ‘cupping’ on the front tread, which can severely compromise the bike’s high-speed stability.
Electrical and Ignition
The electrical system is anchored by the 66010-97E battery, which provides the high cold-cranking amps (CCA) necessary for the high-compression Milwaukee-Eight starters. When replacing spark plugs, ensure the gap is set to factory specifications: the Twin Cam uses 6R12 plugs, while the M8 requires the specialized 60100003 long-reach plugs to clear the four-valve head geometry.
Frequently Asked Questions
Q: Can I use automotive oil in my FLHTK?
A: No. Harley-Davidson engines share oil with the primary drive or require specific additives to handle the high heat of air/liquid-cooled V-Twins. Always use motorcycle-specific 20W50.
Q: Why did Harley-Davidson discontinue the FLHTKL?
A: The ‘Low’ model was integrated into the standard touring customization options through the ‘Reach’ seat and suspension accessory lines, though the original FLHTKL remains highly sought after on the secondary market for its factory-lowered geometry.