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Factory Workshop SpecificationsPlatform Gen: 1990–2026

2026 Harley-Davidson Fat Boy / Fat Boy 114 (FLSTF / FLFB / FLFBS) Specifications & Consumables

Official workshop technical reference: fluid capacities, spark plug codes, drive chain specs, and tire inflation pressures.

Gen 1990–2026

Factory Platform Compatibility: All workshop fluid capacities, maintenance milestones, torque specifications, and consumables on this specification sheet are factory-identical across model years 1990 through 2026.

Engine
1868cc
Drive
Not Available
Cooling
Air / Oil-Cooled with Dual Internal Counterbalancers

Engineering Subsystem Workbenches & Calculators

Dedicated deep-dive diagnostic tools, torque matrices, wiring pinouts, and calculators tailored for 2026 Harley-Davidson Fat Boy / Fat Boy 114 (FLSTF / FLFB / FLFBS).

10 Dedicated Engineering Spoke Pages
Subsystem Guide/torques

Fastener Torques

Engine drain plug, axle spindles, caliper mounts, triple clamp pinch bolts & thread lubrication derating guide.

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Subsystem Guide/fluids

Fluids & Capacities

Oil: 4.70 L (5.00 US qt) • Coolant: Not Applicable (Air / Oil Cooled) • Brake: N/A

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Subsystem Guide/fuses-relays

Fuses & Relays

Main: N/A • Location: N/A

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Subsystem Guide/compression

Compression & Leakdown

Ratio: N/A

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Subsystem Guide/valves

Valve Clearances

Intake: N/A mm • Exhaust: N/A mm

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Subsystem Guide/fuel-delivery

Fuel Delivery & TB Sync

Idle: N/A • Rail Pressure: N/A • Vacuum: N/A

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Subsystem Guide/electrical

Charging & Battery

Battery: YTX20HL-BS / H-D 65989-97E

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Subsystem Guide/tires

Tires & Gearing

Front: 160/60R18 70V • Rear: 240/40R18 79V

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Subsystem Guide/suspension

Suspension & Sag

Front Travel: N/A • Rear Travel: N/A

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Subsystem Guide/maintenance

Maintenance Schedule

Oil: N/A • Valves: N/A • Plugs: N/A

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Fluids & Service Capacities
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Engine Oil (Drain & Filter Change)4.70 L (5.00 US qt)
Engine Oil (Drain Only)N/A
Recommended Oil ViscosityH-D Screamin' Eagle SYN3 20W-50 Full Synthetic or Genuine H-D 360 20W-50
Coolant System CapacityNot Applicable (Air / Oil Cooled)
Brake Fluid StandardNot Available
Drivetrain, Chain & Gearing
Drive Chain PitchBelt Drive
Chain Link Count133-Tooth Carbon-Fiber Reinforced (24mm width)T Belt
Front Sprocket TeethN/A
Rear Sprocket TeethN/A
Final Drive ConfigurationCarbon Belt Drive
Ignition & Electrical Specifications
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OEM Spark Plug Part NumberH-D 6R10 / 6R12
Electrode Spark Plug Gap0.8–0.9 mm (0.031–0.035 in)
OEM Battery Reference CodeYTX20HL-BS / H-D 65989-97E
Battery Output & RatingNot Available
Spark Plug Inspection IntervalN/A
Wheels, Tires & Inflation Pressures
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Front Tire Dimensions160/60R18 70V
Cold Front Inflation PressureN/A
Rear Tire Dimensions240/40R18 79V
Cold Rear Inflation PressureN/A
OEM Wheel Rim Widths (F / R)3.50" / 5.50"

Official NHTSA Safety Recalls & Technical Bulletins

3 Active Campaigns
U.S. Department of Transportation compliance database (Title 49 U.S.C. Chapter 301).
Verify VIN on NHTSA.gov
The U.S. National Highway Traffic Safety Administration reports 3 safety recall campaigns associated with this platform. Independent repair shops and riders should confirm that authorized dealership warranty remedies have been applied.
NHTSA #25V375000SUSPENSION:REAR:SHOCK ABSORBER
▼
Defect Description

Harley Safety Recall 0188: 2018–2024 Softail rear shock pre-load adjuster mounting tab can fracture under vibration, potentially allowing adjuster to contact rear tire.

Safety Hazard / Consequence

Contact between adjuster body and rear tire can cause tire damage, sudden loss of tire pressure, and loss of vehicle control.

Factory Remedy & Repair Action

Dealers install a reinforced retention bracket kit free of charge.

NHTSA #23V591000SUSPENSION:REAR:SHOCK ABSORBER
▼
NHTSA #18V734000POWER TRAIN:CLUTCH ASSEMBLY
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OEM Workshop Archives

Official Factory Service Bulletins & Field Updates

2 Documented Bulletins
Bulletin #HD-0181Safety Recall Bulletin 0181 & 0182 / NHTSA 23V-591: Softail Rear Shock Absorber Pre-Load Fastener Rear Tire Contact
Source: RCLRPT-23V591-6615.PDF
Mandated Torques:Torque: 12–15 N·m (106–133 in-lb) (Pre-load Adjuster Bracket Mounting Screw)Torque: 95–108 N·m (70–80 lb-ft) (Upper & Lower Shock Eye Mount Bolts)Torque: 136–149 N·m (100–110 lb-ft) (Rear Axle Cone Nut)
Consumable Specs:Loctite 243 Medium Strength Blue ThreadlockerIsopropyl Alcohol Surface Cleaner
Genuine Part Numbers:102008499150010454000142
Recalls 0181 & 0188 • NHTSA 23V-591 & 25V-375

Harley-Davidson Softail Mono-Shock Pre-Load Adjuster & Tire Clearance Architecture

Fast adjuster bracket reinforcement, tire clearance inspection (≥ 10 mm), and 95–108 N·m shock mounting torques.

SOFTAIL HIDDEN MONO-SHOCK CHASSISFRONT EYE: 95-108 N·mREAR EYE: 95-108 N·mKNOB (0-5)BRACKET: 12-15 N·mLOCTITE 243 BLUE240mm REAR TIREGAP ≥ 10 mmMANDATED SERVICE & RECALL PROTOCOL:• Fastener: Retorque adjuster screw to 12–15 N·m (106–133 in-lb) with Loctite 243 Blue.• Bracket Kit: Install reinforced retention bracket (Recall 0188 countermeasure).• Clearance: Verify ≥ 10 mm air gap between adjuster knob and tire across full stroke.
Shock Mounting Bolts95–108 N·m (70–80 lb-ft)
Adjuster Bracket Screw12–15 N·m (106–133 in-lb)
Chemical ThreadlockerLoctite 243 (Medium Blue)
Dynamic Tire Clearance≥ 10.0 mm (0.39 in)
Bulletin #HD-TSB-21-04Technical Service Bulletin TSB-21-04: Fat Boy Solid Lakester Wheel Hub, 240mm Rear Tire & Pulley Torques
Source: H-D_TSB_21-04_Lakester_Hub.pdf
Mandated Torques:Torque: 75–88 N·m (55–65 lb-ft) + 45°–50° Turn (Rear Driven Pulley Bolts - Loctite 262 Red)Torque: 41–47 N·m (30–35 lb-ft) (Front & Rear Brake Rotor Torx Screws - Loctite 243 Blue)Torque: 136–149 N·m (100–110 lb-ft) (Rear Axle Cone Washer & Nut)Torque: 102 N·m (75 lb-ft) (Front Axle)Torque: 24–27 N·m (18–20 lb-ft) (Front Axle Pinch Bolts)
Consumable Specs:Loctite 262 High-Strength Red Threadlocker (Pulley Bolts)Loctite 243 Medium-Strength Blue Threadlocker (Rotor Screws)Anti-Seize Lubricant (Axle Shafts)
Genuine Part Numbers:410003913700021441500147
Fat Boy Icon • Lakester Solid Disc Driveline

Harley-Davidson Fat Boy Solid Lakester Wheel & 240mm Rear Driveline Hub Assembly

Cast solid disc wheel torques, 240/40R18 rear tire specs, 136–149 N·m rear axle, and driven pulley angle torque.

REAR AXLE NUT: 136-149 N·m(100-110 lb-ft) CONE WASHER66T / 68T DRIVEN PULLEYBOLTS: 75-88 N·m + 45°-50°(LOCTITE 262 RED • NEW BOLTS)292mm REAR ROTORBOLTS: 41-47 N·m(30-35 lb-ft • LOCTITE 243)FAT BOY DRIVELINE SPECS:• Front Rim: 18 x 4.5 in Lakester• Rear Rim: 18 x 8.0 in Lakester• Front Tire: 160/60R18 (36 psi)• Rear Tire: 240/40R18 (42 psi)• Front Axle Nut: 102 N·m• Front Pinch Bolt: 24–27 N·m• Rear Axle Nut: 136–149 N·m• Pulley Bolts: 75–88 N·m + 45°• Rotor Bolts: 41–47 N·m• Belt Deflection: 9.5–12.7 mm• Bearing End Play: < 0.05 mm• Caliper Mounts: 38–52 N·m
Rear Axle Nut136–149 N·m (100–110 lb-ft)
Driven Pulley Bolts75–88 N·m + 45°–50° Turn
Brake Rotor Screws41–47 N·m (30–35 lb-ft)
Front Axle Nut102 N·m (75 lb-ft)

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2026 Harley-Davidson Fat Boy / Fat Boy 114 (FLSTF / FLFB / FLFBS) Factory Workshop Specs & Maintenance Guide | WowShopper | WowShopper Motorsports