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1957 Sportster

Note: Click on the words lit up in blue on this page to link to more specific information in the Sportsterpedia.

The Sportster XL was introduced as “a modern, up-to-date power plant.” www.motorcycleclassics.com_media_images_mcc_editorial_articles_magazine_articles_2011_05-01_1957_harley-davidson_sportster_xl_sportster-1.jpg

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)

Model Production Numbers

  • XL - Number Produced: 1,983

Colors

  • Skyline Blue with Birch White tank panels. 2)
  • Pepper Red with Black tank panels. 3)
  • Birch White with Black tank panels. 4)
  • Black with Pepper Red tank panels. 5)
  • Options (no charge): 6)
    • Fenders to match tank panel when panel is a standard color.
    • Birch White - (indicate either solid or with black panels).
    • Any standard color without tank panels.
  • Options (extra charge): 7)
    • Metallic Midnight Blue with Birch White tank panels.
    • Spring Special: Nugget Gold.

Vehicle Identification

Frame Numbers

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.

Engine Serial Numbers

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)
57XL (example)
12345
Example: (57XL 12345) indicates a 1957 XL model and is stamped on the Left Engine Case Between the Cylinders 8)
Example Serial Number on Engine Reads: 57XL12345
57 XL 12345

Illustrations

The following illustrations are displayed for historic and period specific parts identification only. Refer to the original OEM documents for additional information. 9)
Click on any illustration below to enlarge.

1957_xl883_illust_engine.jpg

Specifications

Model Designation

  • XL

Dimensions

  • Wheelbase: 56.5 in / 143.51 cm 10)
  • Overall Length: 87 in / 221 cm
  • Overall Width: 34 in / 86.36 cm
  • Overall Height: 40.5 in
  • Saddle height 26-7/8 in to 29 in / 68.26 cm to 73.66 cm
  • Road Clearance: 2.5 in to 4-5/8 in / 6.35 cm to 11.74 cm

Engine

  • Engine type: 4 cycle Overhead Valves, 45 degree V2 11)
  • Displacement: 53.9 ci / 883 cc (900 cc advertised)
  • Compression Ratio: 7.5:1
  • Bore: 3 in / 76.2 mm
  • Stroke: 3.8125 in / 96.8 mm
  • Horsepower: 42 @ 5,500 rpm
  • Taxable Horsepower: 7.2
  • Torque: 48 ft/lb @ 3.600 RPM
  • Weight: 204 lbs.
  • 4 Cams
  • Gear driven type oil pump.
    Oil pump pressure (gauge mounted in place of oil pressure switch):
    • Idle, with spark retarded (Min: 3-7 psi)
    • Normal riding conditions: 10-14 psi (6 psi at 20 mph)
  • Ignition: Battery Ignition (circuit breaker/points/timer/distributor)
  • Spark Plugs
    • #4 for everyday use.
    • #5 for hard service.
  • Fuel System: Linkert DC carburetor.

Capacities

  • Fuel capacity: 4.1 gal / 15.52 l12)
  • Oil Capacity: 3 qts. / 2.83 l
  • Transmission Capacity: 1.5 pints / .71 l

Clutch

  • Multi-Disc dry clutch-pack with alternate steel and fiber friction plates.13)

Drivetrain

  • Constant Mesh - right side foot shift 14)
  • Speeds - 4 Forward
  • Number of Sprocket Teeth
    • Engine: 34
    • Clutch: 59
    • Transmission: 21
    • Rear Wheel: 51
  • Standard Gear Ratios
    • 1st: 10.63:1
    • 2nd: 7.69:1
    • 3rd: 5.82:1
    • 4th: 4.21:1

Tires

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 15) but not exceeding manuf max tire pressure.

  • XL:
    • Front: 3.50 x 18 (tire pressure: 14 psi / .96 bar)
    • Rear: 3.50 x 18 (tire pressure: 18 psi / 1.24 bar)

External Links

8)
1953-1963 HD Parts Catalog backside of front cover
9)
illustrations from various academic journals
10) , 11)
Harley-Davidson 1957 - 1969 Service Manual
12)
Harley-Davidson 1960 Sportster Service Manual
13)
1957-1969 HD FSM pg 4A-3
14)
1957-1969 HD FSM pg 1A-3
15)
1959-1964 HD FSM pg 1A-3
16)
http://www.harleykmodel.com/literature/spare-parts-catalogs/documents/99451-57/99451-57.pdf
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