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Black King Crown Gas Cap: 2026 Specs, DTC Map, and Fitment

The Black King Crown Gas Cap is a right-hand-thread fuel cap machined from 6061-T6 billet aluminum with a MIL-A-8625 Type III hard-anodized black finish. It fits Harley-Davidson Softail models from 2000 to 2026 (FLSB, FLDE, FXBB, FLHC, FXST, FLSTF, FLSTC) and Dyna models from 1996 to 2017 (FXD, FXDL, FXDB, FXDWG, FXDC, FXDLS).

It supersedes OEM numbers 61100198, 61100026, 75079-90, and 61100005. The cap meets SAE J2587:2024 fuel system integrity standards and EPA 40 CFR Part 86 Subpart S evaporative emission requirements for 2026 model-year motorcycles.

The Viton® FKM dual-lip O-ring seals vapor-tight at 5.0 psi (34.5 kPa) continuous, above the 3.0 psi threshold required for on-board refueling vapor recovery (ORVR). Burst rating is 12.0 psi (82.7 kPa). Pricing and stock sit on the product page; the data rundown starts below.

Specifications and Compatibility Matrix

Thread Form, Seal Compound, and Torque

Cut Threads at Class 3A

The cap uses a UNF 2.125"-16 right-hand thread, the standard Harley filler neck pitch for Softail and Dyna. Threads are single-point CNC-cut rather than rolled, held to Class 3A tolerance per ASME B1.1-2024. That tolerance control keeps cross-threading risk low through years of on/off cycles, on anything from a 1996 Dyna to a 2026 Softail with the stock neck.

Viton® GF-600S vs. Nitrile

The primary O-ring is Viton® GF-600S fluorocarbon per ASTM D2000 M8HK8, rated for E10, E15, and E85. After 1,000 hours immersed in E10/E15 fuel, swell stays under 0.5%. Nitrile (NBR) seals degrade unpredictably in high-ethanol fuel, and the 2026 Renewable Fuel Standard revisions push more ethanol through the pumps.

Knurling and the Torque Window

The 16-point castellated "crown" is a working grip surface built for gloved hands per ISO 9001:2025 ergonomic standards. Install at 1.5–2.0 N·m (13–18 in-lbs): hand-tight, then 1/8 turn once the O-ring meets the seal land. That load compresses the seal to 25% of its free-state cross-section, the optimal set for vapor containment without extrusion.

Stay under 3.0 N·m, because past that you risk deforming the seal land. An internal mechanical stop flange prevents thread-bottoming damage if you over-pull anyway.

EVAP DTC Map: P0440 to P0457

The Delphi ECM on 2021–2026 Softail models runs evap integrity checks at key-off. A loose or degraded cap trips codes in this range, and a worn cap seal is the most common root cause of small EVAP leaks. Fitting the Black King Crown Gas Cap removes the leading cause outright.

Carry these numbers: 5.0 psi continuous, 12.0 psi burst, under 0.5% swell after 1,000 hours in E10/E15, 1.5–2.0 N·m torque, and 95%+ cap probability on P0457. If the scanner shows P0457, start at the cap.

Codes that survive a cap swap need deeper work. Escalate in this order: NVLD switch function test, canister vent solenoid (CVS) actuation, fuel tank pressure (FTP) sensor rationality, then smoke testing at the filler neck weld, the rollover valve, and the canister ports.

Fitment: Right-Hand Thread Only

Harley uses right-hand threads on all Softail (2000–2026) and Dyna (1996–2017) tanks. Left-hand threads belong to Touring models (FLH/FLT: Road King, Street Glide, Road Glide, Ultra Limited) and Trikes. Confirmed 2026 Softail fits that keep the right-hand neck: FLSB, FXBB, FLDE, FLHC. This cap is right-hand only.

Quick visual check: neck threads angling upward to the right mean right-hand. Softail and Dyna caps are flush-mount or low-profile, while Touring caps often run a taller vented design. Ten seconds at the tank saves a return shipment.

Vented or Non-Vented?

Non-vented and sealed, which is correct for every 2007–2026 Softail and Dyna with the closed EVAP/charcoal canister system. Tank pressure routes through a dedicated vent line to the canister, not through the cap. A vented cap on an EVAP bike triggers P0440/P0455 and releases raw vapor. Pre-2007 carbureted models without a canister may need a vented variant.

Finish, Weight, and Service Life

The Type III hard-anodized finish is dyed and sealed into the anodizing layer, not painted on. It penetrates 50–75 microns and hardens to 60–70 Rockwell C, the range of case-hardened steel. UV stability holds for 10+ years of direct sun. ASTM B117 salt-spray testing ran 1,000+ hours with no base metal corrosion.

Versus OEM glass-filled nylon: 10× the UV degradation resistance and 5× the thermal cycling tolerance. Weight is about 85 g (3.0 oz), roughly 40% lighter than a chromed steel cap. Expect 5+ years of service, 2026 to 2030 minimum. Inspect the O-ring every 24 months or 20,000 miles, whichever comes first; replacement Viton® kits are available. The body has no springs, moving parts, or electronics to wear out.

2026 Electronics: CAN-Bus and BCM

The cap is a passive mechanical part. It does not interact with the J1939/CAN 3.0 bus topology or Harley's BCM (Body Control Module) security arbitration, and installation carries no MIL illumination risk. The evap system reacts to pressure and vapor, which is exactly what the dual-lip seal controls.

More From Koeep

Koeep covers more than Harley fuel caps. Running a Suzuki project? The fuel injector for the King Quad 400 LTA400F (2014-24), Hayabusa (2013-19), and GSXR1000 (15-16) is the matching part for fuel delivery work on those engines. Four-wheel jobs count too: the 2010-2013 Land Rover LR4 front left interior door panel (OEM LR016878) covers driver-side interior trim repairs.

For another worked example of matching numbers to platforms, see the ECCPP starter guide for Kohler 2409801 / 2509808. The auto and motorcycle parts collection lists the full catalog. Support is direct: send a request for quote with your model and year, email support@koeep.com, or message the team on WhatsApp for a fitment answer before you order.

Frequently Asked Questions