Harley-Davidson Fat Boy Lo 103 / Fat Boy S 110 (FLSTFB) — OEM Fluid, Tire Pressure & Maintenance Specs
1,690cc Air-Cooled Counterbalanced 45° V-Twin Twin Cam 103B (110B on S) · Source: Harley-Davidson Fat Boy Lo 103 / Fat Boy S 110 (FLSTFB) (2010–2017) Official Owner’s Manual Maintenance Specifications
According to the Harley-Davidson Fat Boy Lo 103 / Fat Boy S 110 (FLSTFB) (2010–2017) Official Owner’s Manual Maintenance Specifications, the 2010–2017 Harley-Davidson Fat Boy Lo 103 / Fat Boy S 110 (FLSTFB) (chassis FLSTFB/FLSTFBS (110 S)) requires 2.6 L (2.75 US qt) of SAE 20W-50 (JASO MA2, H-D 360 SAE 20W-50 / SYN3) engine oil for a drain-only change and 2.8 L (2.96 US qt) with filter service (HD 63798-99A / 63731-99A (HF171C)). Standard solo cold tire pressure is 248 kPa / 2.48 bar / 36 PSI front (140/75R17 67V) and 290 kPa / 2.90 bar / 42 PSI rear (200/55R17 78V), paired with 2× HD 6R12 (32362-04A) spark plug(s) and a YTX20HL-BS / YIX30L-BS battery.
Drain only: 2.6 L (2.75 US qt)
R 290 kPa (2.90 bar)
Est. Range: ~336 km (209 mi)
1. Engine Lubrication, Filter & Clutch Specifications
| Clutch Architecture | Wet Multi-Plate Manual Clutch NEVER use JASO MB |
|---|---|
| Recommended Viscosity & Grade | SAE 20W-50 · JASO MA2 · H-D 360 SAE 20W-50 / SYN3 |
| Oil Volume (Drain / With Filter / Overhaul) |
• Drain only: 2.6 L (2.75 US qt) • With filter/strainer: 2.8 L (2.96 US qt) • Complete dry overhaul: 3.3 L (3.49 US qt) |
| OEM Oil Filter Code & Type | HD 63798-99A / 63731-99A (HF171C) |
| Correct Oil Level Check Method | At full operating temperature resting ON THE SIDESTAND (Jiffy Stand); thread dipstick in to read |
| Oil Drain Bolt Torque | 24 N·m (17.7 lb-ft / 2.45 kgf·m) — Use fresh crush washer |
| Primary Chaincase Fluid | 1120 ml (1.12 L) — H-D Formula+ Primary Fluid (1,120 ml / 38 oz) |
| Separate Transmission / Gearbox Oil | 830 ml (0.83 L) — H-D Formula+ or SAE 80W-140 Gear Oil (830 ml / 28 oz) |
2. Cold Tire Pressures, Wheels, Ignition & Drivetrain
| Front / Rear OEM Tire Sizes | Front: 140/75R17 67V · Rear: 200/55R17 78V (Tubeless) |
|---|---|
| Cold Tire Pressure — Solo Riding |
Front: 248 kPa / 2.48 bar / 36 PSI Rear: 290 kPa / 2.90 bar / 42 PSI |
| Cold Tire Pressure — 2-Up / Loaded Touring |
Front: 248 kPa / 2.48 bar / 36 PSI Rear: 290 kPa / 2.90 bar / 42 PSI |
| OEM Spark Plug & Quantity | HD 6R12 (32362-04A) × 2 (Gap: 0.97–1.09 mm) |
| OEM Battery Code & Rating | YTX20HL-BS / YIX30L-BS (12V 18–28Ah Heavy-Duty AGM) |
| Final Drive Maintenance | Carbon/Aramid Reinforced Secondary Belt — Inspect belt deflection and pulley debris |
| Brake Fluid & Coolant | DOT 4 · Air/Oil-Cooled Engine (No liquid coolant) |
3. Ergonomics, Range & Scheduled Service Intervals
| Displacement · Max Power · Peak Torque | 1690 cc · 77 hp @ 5,010 rpm · 132 N·m (97.4 lb-ft) @ 3,250 rpm |
|---|---|
| Seat Height & Wet Curb Weight | 670 mm (26.4 in) · 331 kg (730 lbs) |
| Fuel Tank & Est. Real-World Range | 18.9 L (5.0 US gal) · ~17.8 km/L → ~336 km (209 mi) |
| OEM Scheduled Maintenance Intervals |
• First Break-In: 1,600 km • Engine Oil / Filter: 8,000 km / 8,000 km • Air Filter / Spark Plug: 24,000 km / 32,000 km • Valve Clearance Check: 48,000 km |
4. Generation Cutoffs & Real-World Wrenching Gotchas
Model-Year & Chassis Generation Notes
Sold globally as the Fat Boy Special with lowered suspension and black/satin-chrome trim, joined in 2016–2017 by the hydraulic-clutch 1,801cc Twin Cam 110B Fat Boy S (FLSTFBS).
Oil & Clutch Mechanical Engineering Note
Uses the counterbalanced Twin Cam B 3-Hole horseshoe-tank dry sump taking 2.8 L of SAE 20W-50 engine oil, 1,120 ml Formula+ primary fluid, and 830 ml gear oil.