Harley-Davidson Fat Boy 1340 Evolution (FLSTF Evo Big Twin) — OEM Fluid, Tire Pressure & Maintenance Specs
1,338cc Air-Cooled 45° V-Twin Single-Cam Pushrod OHV Evolution 80 · Source: Harley-Davidson Fat Boy 1340 Evolution (FLSTF Evo Big Twin) (1990–1999) Official Owner’s Manual Maintenance Specifications
According to the Harley-Davidson Fat Boy 1340 Evolution (FLSTF Evo Big Twin) (1990–1999) Official Owner’s Manual Maintenance Specifications, the 1990–1999 Harley-Davidson Fat Boy 1340 Evolution (FLSTF Evo Big Twin) (chassis FLSTF (Evo 80)/FLSTC (Evo 80)) 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 63796-77A / HF170C (Evo 30-Micron Filter!)). Standard solo cold tire pressure is 248 kPa / 2.48 bar / 36 PSI front (MT90B16 72H) and 248 kPa / 2.48 bar / 36 PSI rear (MT90B16 74H), paired with 2× HD 5R6A / NGK BPR5ES spark plug(s) and a YTX20L-BS / HD 65989-97 battery.
Drain only: 2.6 L (2.75 US qt)
R 248 kPa (2.48 bar)
Est. Range: ~278 km (173 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 63796-77A / HF170C (Evo 30-Micron Filter!) |
| 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 | 946 ml (0.95 L) — H-D Formula+ Primary Fluid (1,120 ml / 38 oz) |
| Separate Transmission / Gearbox Oil | 710 ml (0.71 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: MT90B16 72H · Rear: MT90B16 74H (Tubeless) |
|---|---|
| Cold Tire Pressure — Solo Riding |
Front: 248 kPa / 2.48 bar / 36 PSI Rear: 248 kPa / 2.48 bar / 36 PSI |
| Cold Tire Pressure — 2-Up / Loaded Touring |
Front: 248 kPa / 2.48 bar / 36 PSI Rear: 276 kPa / 2.76 bar / 40 PSI |
| OEM Spark Plug & Quantity | HD 5R6A / NGK BPR5ES × 2 (Gap: 0.97–1.09 mm) |
| OEM Battery Code & Rating | YTX20L-BS / HD 65989-97 (12V 18.0Ah AGM) |
| Final Drive Maintenance | Carbon/Aramid Reinforced Secondary Belt — Inspect belt deflection and pulley debris |
| Brake Fluid & Coolant | DOT 5 (Silicone) · Air/Oil-Cooled Engine (No liquid coolant) |
3. Ergonomics, Range & Scheduled Service Intervals
| Displacement · Max Power · Peak Torque | 1338 cc · 56 hp @ 5,000 rpm · 98 N·m (72.3 lb-ft) @ 3,000 rpm |
|---|---|
| Seat Height & Wet Curb Weight | 685 mm (27.0 in) · 309 kg (681 lbs) |
| Fuel Tank & Est. Real-World Range | 15.9 L (4.2 US gal) · ~17.5 km/L → ~278 km (173 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
Immortalized in Terminator 2 from 1990 to 1999, the 80 cu-in (1,338cc) Evolution Big Twin FLSTF pairs an unbalanced single-cam V-twin, Keihin CV40 carburetor, 5-speed box, and DOT 5 Silicone brakes.
Oil & Clutch Mechanical Engineering Note
Because Evo Big Twins filter oil on the low-pressure return line, fit ONLY low-restriction 30-micron Evo filter 63796-77A / HF170 (never 5-micron TC/M8 HF171) and use DOT 5 Silicone brake fluid.