The Sportster XL was introduced as “a modern, up-to-date power plant.”

In 1952, the W models were replaced with the revered 45-cubic inch side-valve K series. The new K-models included an integrated four-cam engine and four-speed transmission design, along with foot shift, swingarm rear suspension, and telescopic front forks to compete with smaller, sportier motorcycles coming mainly from Great Britain. Essentially, the new XL motor was an updated K-model engine with larger displacement, overhead valves and higher compression. - Harley-Davidson Archives Copyright H-D ¹⁾

Number produced: 1983²⁾

Original Price: $1103

There was no frame identification for purpose of ownership on 1957-1969 model Sportsters.
However, there were stampings on the different parts of the frame combined with certain features that can be used to date the frame.
Click Here to view Ironhead Frame Identification in the Sportsterpedia.

The only numbers for the purpose of identification were on the engine case.

• For 1957-1961 models, the engine serial number is stamped on the left side of the engine case between the two cylinders.
  First 4 or 5 digits are the year and bike model followed by a series of 4 or 5 numbers that established the individual serial number for each bike.
  

Click Here for more specific information on serial numbers and VINs in the Sportsterpedia.

Engine Serial Number for 1957 Sportsters
Model Year (first 2 digits)	Model (next few digits) (up to 4)	Sequential Serial# (remaining digits)
57	XL	(example) 12345
Example: (57XL 12345) indicates a 1957 XL model and is stamped on the Left Engine Case Between the Cylinders 3)
Example Serial Number on Engine Reads: 57XL12345
57	XL	12345

The following illustrations are displayed for historic and period specific parts identification only. Refer to the original OEM documents for additional information. ⁴⁾
Click on any illustration below to enlarge.

• Model Designation: XL

• Engine type: 4 cycle Overhead Valves, 45 degree V2 ⁵⁾
• Kick start only ⁶⁾
• Displacement: 55 ci / 883 cc (900 cc advertised) ⁷⁾
• Compression: 7.5:1 ⁸⁾
• Hemi-spherical style heads
• Bore: 3 in / 76.2 mm ⁹⁾¹⁰⁾
• Stroke: 3.8125 in / 96.8 mm ¹¹⁾¹²⁾
• 90 Degree Valve Angle
• Horsepower: 42 @ 5,500rpm ¹³⁾
• Torque: 48 ft-lb @ 3600 RPM ¹⁴⁾
• 4 Cams
• Oil pump pressure: 6 psi @ 20 MPH ¹⁵⁾
• Fuel System: Linkert DC carburetor ¹⁶⁾
• Ignition: Ignition spark is produced by operation of a circuit breaker, ignition coil and spark plugs.
  The breaking of a single set of breaker points by a double lobe cam on the timer shaft determines the spark timing.
  The narrow lobe times the front cylinder while the wider lobe times the rear. ¹⁷⁾

• Fuel capacity: 4 gal / 15.14 l¹⁸⁾
• Oil Capacity: 3 qts. / 2.83 l ¹⁹⁾
• Transmission Capacity: 1.5 pints / .71 l ²⁰⁾
• MPG: 50mpg (est.)²¹⁾

• Multi-Disc dry clutch-pack with alternate steel and fiber friction plates.²²⁾

• Weight: 495 lb / 225 kg²³⁾
• Wheelbase: 56.5 in / 143.51 cm ²⁴⁾
• Overall Length: 87 in / 221 cm ²⁵⁾
• Overall Width: 34 in / 86.36 cm ²⁶⁾
• Overall Height: 40.5“ ²⁷⁾
• Road Clearance: 2.5 in min / 6.35 c minimum, 4-5/8 in max ²⁸⁾
• Saddle height 26-7/8“ to 29”

• Constant Mesh - Foot shift
• Speeds - 4 Forward
• Number of Sprocket Teeth
  • Engine: 34 ²⁹⁾
  • Clutch: 59 ³⁰⁾
  • Transmission: 21 ³¹⁾
  • Rear Wheel: 51 ³²⁾
• Gear Ratios
  • 1st: 10.63:1 ³³⁾
  • 2nd: 7.69:1 ³⁴⁾
  • 3rd: 5.82:1 ³⁵⁾
  • 4th: 4.21:1 ³⁶⁾

• Front and rear: 3.50 x 18
• Tire pressure (based on a rider weighing app. 150 lbs or more)
• For each 50 lbs of overload, increase rear tire pressure by 2 lbs., front by 1 lb. ³⁷⁾but not exceeding max tire pressure.
  • Front: 14 psi / .96 bar
  • Rear: 18 psi / 1.24 bar

• XL

• Pepper Red / Black Tank Panels³⁸⁾
• Skyline Blue / Birch White Tank Panels³⁹⁾
• Birch White / Black Tank Panels⁴⁰⁾
• Black / Pepper Red Tank Panels⁴¹⁾

1957 Parts Manual⁴²⁾

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