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1957 Sportster

Vehicle Identification Number (VIN)

  • The serial number is stamped on the left side of the engine case. The first 5 or 6 digits represent the year and model 1)

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 2)

Number produced: 19833)

Original Price: $1103

Specifications

1957-sportster-engine.jpg

  • Model Designation: XL

Engine

  • Engine type: 4 cycle Overhead Valves, 45 degree V2 4)
  • Displacement: 55 ci / 900 cc
  • Compression: 7.5:1
  • Hemi-spherical style heads
  • Bore: 3 in5)
  • Stroke: 3 13/16 in6)
  • 90 Degree Valve Angle
  • Horsepower: 42 @ 5,500rpm 7)
  • Torque: 48 ft-lb @ 3600 RPM
  • Fuel System: Linkert DC carburetor 8)

Capacities

  • Fuel capacity: 4 gal / 15.14 l9)
  • Oil Capacity: 3 qts. / 2.83 l 10)
  • Transmission Capacity: 1.5 pints / .71 l 11)
  • MPG: 50mpg (est.)12)

Dimensions

  • Weight: 495 lb / 225 kg13)
  • Wheelbase: 56.5 in / 143.51 cm 14)
  • Overall Length: 87 in / 221 cm 15)
  • Overall Width: 34 in / 86.36 cm 16)
  • Overall Height: 40.5“ 17)
  • Road Clearance: 2.5 in minimum / 6.35 c minimum
  • Saddle height 26-7/8“ to 29”

Drivetrain

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

Tires

  • 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. 18)but not exceeding max tire pressure.
    • Front: 14 psi / .96 bar
    • Rear: 18 psi / 1.24 bar

Models

  • XL

Colors

  • Pepper Red / Black Tank Panels19)
  • Skyline Blue / Birch White Tank Panels20)
  • Birch White / Black Tank Panels21)
  • Black / Pepper Red Tank Panels22)

1957 Parts Manual23)

Back to Sportster History Index The Sportster XL was introduced as “a modern, up-to-date power plant” and weighing in at 204 lbs and making 42 Horsepower at 5,500 RPMs. 2)

Road Clearance 2-1/2“ to 4-5/8” 3)

55cid 7.5:1 Compression, hemi-spherical style heads, 90 degree valve angle, OHV V-twin, 4 cams 4)5)

48 ft-lbs of torque at 3600 RPMs.

1-11/16“ Dia. intake valves 6)

3”x3.8“ bore and stroke

Piston Displacement (883cc) 53.9 cu. in.

Kickstart only

18” wheels standard

Speedometer designed into the sheet metal of the fork shroud.

Telescoping front forks

Fuel tank capacity 4.4 gallons.

Oil tank (3 quarts) located under the seat on the right side using a recirculating oiling system

Two brush generator w two-unit voltage regulator powering a six volt system

Coil-over shocks

'Jubilee' trumpet horn mounted on the right side of the engine, power pack on the left side

Paint color, 'HD 100' enamel

Standard solo seat

Options included

Windshield

Saddlebags

Dual seat

Front drum brakes (operated by a lever on the left handlebar)

Rear drum brakes (operated by a foot pedal on the left side)

Rear swingarm with Timken bearings at pivots.

Short-barrel Linkert Carburetor

Engine ID numbers on a pad located on the left side between the cylinders

Straight retained bearings on gear shaft

Roller valve lifters were called (High Speed Racing Tappets)

Spark plugs were air cooled and could be dis-assembled

Cams ramped on both closing and opening side

Stellite-faced exhaust valves

Aluminum alloy pushrods extend up through the covers to reach the rocker

Cam-ground aluminum pistons w/ chrome plated top ring, non plated center ring and u-flex lower oil ring

Aluminum rocker boxes enclose valves and rockers

Cast iron barrels and heads

Single-unit construction of engine and transmission

Four speed transmission with a foot shifter on the right side

Seven plate clutch (operated by a lever on the left handlebar)

Primary chain and transmission are lubed by an oil bath separate from engine oil.

Double tapered Timken roller bearings on sprocket shaft

Only Year:

Woodruff keys for camshaft gears

6 splines on drive gear/ second gear shaft

Choke control operated by a left side lever

Tank emblem: Round plastic disc with 2 silver and red quadrants with Red Harley-Davidson name over it, press riveted to the tank.

1)
HD Parts Catalog XLH/XLCH-1000 #(99451-78)
3)
[[http://www.caimag.com/forum/showthread.php?5757-Help-with-1957-xl-sportster/page2|http://www.caimag.com/forum/showthread.php?5757-Help-with-1957-xl-sportster/page2]]
4) , 7) , 9) , 10) , 11) , 14) , 15) , 16)
Harley-Davidson 1957 - 1969 Service Manual
17) , 18)
1959-1964 HD FSM pg 1A-3
19) , 20)
http://xlforum.net/vbportal/forums/showpost.php?p=696133&postcount=6
21) , 22)
http://xlforum.net/vbportal/forums/showpost.php?p=696133&postcount=6
23)
http://www.harleykmodel.com/literature/spare-parts-catalogs/documents/99451-57/99451-57.pdf
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