Harley-Davidson Fat Boy 117 (FLFB 2025 / Gray Ghost) — OEM Fluid, Tire Pressure & Maintenance Specs
1,923cc Air/Oil-Cooled 45° V-Twin Milwaukee-Eight 117 Custom · Source: Harley-Davidson Fat Boy 117 (FLFB 2025 / Gray Ghost) (2025–Present) Official Owner’s Manual Maintenance Specifications
According to the Harley-Davidson Fat Boy 117 (FLFB 2025 / Gray Ghost) (2025–Present) Official Owner’s Manual Maintenance Specifications, the 2025–Present Harley-Davidson Fat Boy 117 (FLFB 2025 / Gray Ghost) (chassis FLFB (117)/FLFBSE (Gray Ghost)) requires 4.3 L (4.54 US qt) of SAE 20W-50 (JASO MA2, Screamin’ Eagle SYN3 20W-50 / H-D 360 20W-50) engine oil for a drain-only change and 4.7 L (4.97 US qt) with filter service (HD 62700296 / 62700297 (HF171C)). Standard solo cold tire pressure is 250 kPa / 2.50 bar / 36 PSI front (160/60R18 70V) and 290 kPa / 2.90 bar / 42 PSI rear (240/40R18 79V), paired with 4× HD 6R10 (31600012 Dual-Plug M8) spark plug(s) and a YTX20HL-BS / HD 65989-97E battery.
Drain only: 4.3 L (4.54 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 · Screamin’ Eagle SYN3 20W-50 / H-D 360 20W-50 |
| Oil Volume (Drain / With Filter / Overhaul) |
• Drain only: 4.3 L (4.54 US qt) • With filter/strainer: 4.7 L (4.97 US qt) • Complete dry overhaul: 5.2 L (5.49 US qt) |
| OEM Oil Filter Code & Type | HD 62700296 / 62700297 (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 | 1065 ml (1.06 L) — H-D Formula+ Primary & Clutch Fluid (900–1,065 ml wet refill) |
| Separate Transmission / Gearbox Oil | 828 ml (0.83 L) — H-D Formula+ or Heavy Synthetic Gear Oil 80W-140 (828 ml / 28 oz) |
2. Cold Tire Pressures, Wheels, Ignition & Drivetrain
| Front / Rear OEM Tire Sizes | Front: 160/60R18 70V · Rear: 240/40R18 79V (Tubeless) |
|---|---|
| Cold Tire Pressure — Solo Riding |
Front: 250 kPa / 2.50 bar / 36 PSI Rear: 290 kPa / 2.90 bar / 42 PSI |
| Cold Tire Pressure — 2-Up / Loaded Touring |
Front: 250 kPa / 2.50 bar / 36 PSI Rear: 290 kPa / 2.90 bar / 42 PSI |
| OEM Spark Plug & Quantity | HD 6R10 (31600012 Dual-Plug M8) × 4 (Gap: 0.8–0.9 mm) |
| OEM Battery Code & Rating | YTX20HL-BS / HD 65989-97E (12V 18.0Ah 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 | 1923 cc · 103 hp @ 4,800 rpm · 168 N·m (123.9 lb-ft) @ 3,000 rpm |
|---|---|
| Seat Height & Wet Curb Weight | 675 mm (26.6 in) · 315 kg (694 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 / 48,000 km • Valve Clearance Check: 48,000 km |
4. Generation Cutoffs & Real-World Wrenching Gotchas
Model-Year & Chassis Generation Notes
Celebrating 35 years of Fat Boy in 2025 (alongside the PVD-finished Gray Ghost Icons edition), the FLFB steps up to the M8 117 Custom engine with standard cornering rider aids and ride modes.
Oil & Clutch Mechanical Engineering Note
Featuring refined cylinder-head oil cooling routing in the M8 117 Custom, the 2025 Fat Boy maintains 3-Hole separation with 4.7 L of SAE 20W-50 engine oil, Formula+ primary, and 6-speed gear oil.
Garage Wrenching Gotchas
- Massive 160 mm front and 240 mm rear Lakester solid-disc wheels mask gradual pressure loss until turn-in turns sluggish; verify 36 PSI front and 42 PSI rear cold with a digital gauge.
- Never rub abrasive metal/chrome polish onto the Gray Ghost edition PVD mirror finish; clean exclusively with non-abrasive microfiber towels and mild wash solution.
5. Frequently Asked Questions (FAQ)
How are engine and separate drivetrain fluid capacities split on the Harley-Davidson Fat Boy 117 (FLFB 2025 / Gray Ghost)?
The engine sump takes 4.3 L drain-only and 4.7 L (4.97 US qt) with filter (HD 62700296 / 62700297 (HF171C)) of SAE 20W-50 (JASO MA2), while isolated drivetrain cavities (primary chaincase 1065 ml, separate gearbox 828 ml) require dedicated gear/chaincase fluid.
How do you accurately check the oil level on the Fat Boy 117 (FLFB 2025 / Gray Ghost), and what are its service intervals?
Bring the engine to full operating temperature and check the Full Hot mark with the motorcycle resting on its sidestand (Jiffy Stand) on level pavement—measuring upright leads to crankcase overfill and breather blow-by. Torque the drain plug to 24 N·m with a new crush washer. Factory oil change intervals are every 8,000 km, with valve clearance inspection every 48,000 km.
What are the cold tire pressures, puncture repair type, seat height, and range of the Fat Boy 117 (FLFB 2025 / Gray Ghost)?
Fitted with 160/60R18 70V front and 240/40R18 79V rear tubeless rims (compatible with roadside plug kits), set cold tire pressures to 36 / 42 PSI (250/290 kPa) solo or 36 / 42 PSI loaded. Seat height is 675 mm (26.6 in) at 315 kg wet weight, delivering ~336 km per 18.9 L tank.