Sportster History (1966-1979)
When Harley-Davidson bolted their new overhead-valve motor to the K-Model frame in 1957, the Sportster legend began. The 883cc displacement (advertised as 900cc) was derived from a 3.81" stroke and a 3.00" bore. Both connecting rods shared a common crank pin, referred to as a 'knife and fork' design. Each valve was operated by its own cam, simplifying valve train geometry. One carburetor fed both front and rear cylinders.
read Early Sportster 1957-1965
The bottom end of the XL motor was nearly the same as the Harley K-Series flathead motor. Inside the rear of the engine cases housed a "unit" four-speed transmission.
The new overhead-valve motor, fitting neatly under the gas tank, sported twin cylinder jugs sitting 45 degrees apart, topped off with a pair of cast-iron cylinder heads. It wasn't until the Evolution Sportsters came out in 1986 that the older models were referred to as "Ironheads".
The oval-shaped "ham-can" air cleaner, brought about by federal emission laws, first appeared in 1966. Also this year, the Linkert carburetor was replaced by a Tillotson, which was less sensitive to lean and tilt, and also helped power and driveability. With newly designed "P" cams, the XLCH produced 15% more power than last year.
First Electric Start Sportster
Until the 1967 XLH, all Sportsters were kickstart only. During 1967 and until 1969, the Motor Company made two cases for the Sportster, one for the kick-start XLCH and one for electric-start XLH. Starting in 1970, all Sportster models shared the same engine cases.
Longer XLH Frame
The frame on the XLH was "kicked-back" just above the swing arm pivot to accommodate the new battery box and electric start. The XLH swing arm was lengthened accordingly. The new longer frame had seat post tubes set 1.5 inches towards the rear, so the upper shock mounts, fender rail mounts got moved rearward.
Sportster Front Forks
In 1968, Harley-Davidson changed the front fork internals which gave an additional 1-inch of travel. Sportster fork tubes, from K models up to 1972 models, (and 1971-1972 Superglides) were 33.4mm in diameter. The fork sliders were steel, and set up for drum brakes only. Rubber fork boots ("gators") were seen on 1957 through 1970 Sportsters.
read Motorcycle Lift Stand Comparison
Up through 1969, the XLCH continued using the early, inch-shorter frame and swing arm, so 1969 is considered the last "real" XLCH. Sportster cylinder-heads were redesigned and fitted with larger, 1-15/16" intake valves. Minor changes in the lower end were seen in 1971, the last year of the 900cc Ironhead engine.
In 1970, H-D started stamping corresponding VIN numbers into frames. All model Sportsters from 1970 thru 1978 had the same frame and swing arm.
"Then Came Bronson" Bike
1970 was the second and final season of the American TV show "Then Came Bronson". The show starred wool-capped Michael Parks riding around the country, finding adventure on his red 1969 Sportster XLH. Bud Ekins, the famous Hollywood stunt man, appeared in several episodes. The show and the bike were both popular, prompting Harley-Davidson to offer a "Bronson Red" paint option for several years.
Sportster-Powered Bonneville Record-Holder
The Bonneville Salt Flats in northwestern Utah have long been a mecca for high-speed competition. It was here that a Sportster-powered streamliner motorcycle broke the world speed record in 1970. The streamliner body was a 15-foot-long aluminum tube, with a cross-section of only 23 inches. Inside was a small cockpit and a modified XLR motor, bored and stroked to 1,480cc (89-cubic inches). The engine ran on 70 percent nitro-methane. Owned by Manning/Riley/Riveria, the pilot was famed Harley-Davidson factory rider Cal Rayborn. His recorded speed of 265.492 mph would stand for fifteen years.
A unique year for Sportsters; 1971 was the last year of the 900cc and first year of the new engine cases. The distributor was moved from the right-side engine case to inside the gear-case, now employing an automatic advance mechanism to aid starting. The fiberglass seat and tail section, known as the 'boat-tail' was available for the second and last year.
read Ironhead Special Tools
Sportsters were converted to a wet clutch setup in 1971. As its name implies, a wet clutch sits in oil, a dry clutch does not. Wet clutches are quieter, but are a harder pull at the clutch lever.
By 1971, Harley-Davidson was selling an average of 6,500 Sportsters annually, which was triple the amount from a decade ago. And in that time, the Ironhead's fan-base had widened deeply. On one end were the racers, who loved its tourquey power and the endless ways to squeeze out more. On the other end were the customizers, who embraced the clean, integrated symmetry of the compact V-twin engine.
1000cc Engine Debut
To keep up with the litre-bikes that Japan was offering, the Sportster motor received a bump in size in 1972. Boring the cylinders 3/16ths of an inch brought displacement from 883cc to 997.3cc (advertised as 1000cc). The increase also gave a more optimum bore-to-stroke ratio, resulting in a smoother running motor. Power was also increased, pushing top-speeds past 110 mph. Quarter-mile times dropped into the mid-thirteens, and by removing the stock exhaust baffles, another half-second could be gained.
The Sportster for 1972 saw several other changes. Prone to vapor lock when the engine was hot, the complex Tillotson carburetor was dropped in favor of the simpler Bendix unit. The new carb also sat closer to the motor, causing less of an obstruction to the rider's right knee. The magneto ignition used on the XLCH models was gone, and in its place was the points/coil/battery system from the XLH. Seat padding was reduced. Sales for the 1972 Sportster nearly doubled from the previous year, with just under 18,000 units sold.
read Best Carburetor For Ironhead Sportster
In 1973, the Sportster frame was modified; the steel casting was eliminated and replaced with steel straps which covered the two frame tubes having the open holes. These two holes previously held the supports for the original solo seat.
Generator Charging Problems
Your Ironhead's generator really doesn't charge the battery until engine rpm is considerably higher than idle. Trips that are less than 15-20 miles are typically not enough to recharge the battery's losses from starting. Consider upgrading to a trouble-free aftermarket generator like Cycle-Electric.
The Cycle Electric generator is a complete 12V charging system with a built-in regulator, simple two-wire hookup, higher output, and longer service life. It's the last generator you will have to buy for your bike!
Front Disc Brake
A front disc brake replaced the drum brake in 1973. Fork tube diameters were increased to 35mm, manufactured first by Kayaba and then by Showa. The 35mm forks had a "pie-slice" brake caliper and cloverleaf rotor, and would later be fitted with dual-disc calipers.
Also this year, the frame was modified, with the steel casting eliminated and replaced with steel straps which covered the two upright frame tubes having the open holes. These two holes held the supports for the original solo seat. 1973 was the first year that turn-signals became mandatory on all motorcycles sold in America.
read Remove and Install Sportster Cam Bushings
AMF-produced Harleys began rolling off the York Pennsylvania assembly line, although the AMF logo had been appearing on gas tanks since 1971. Harley-Davidson was now just one of dozens of divisions in a corporation, and quality control was becoming an issue. Production total for all model Sportsters was 19,960 units.
Under the control of AMF, build-quality seemed secondary. To increase profits, the corporation began streamlining production and cutting the workforce. This led to a 101-day strike by union workers. With the influx of quicker and cheaper Japanese bikes, Harley-Davidson's share of the 750cc and larger motorcycle market had fallen to 21 percent.
The Sound is Good for the Soul
Right-Side to Left-Side Shift
In 1975, new federal regulations required all motorcycles sold in America to have left-side shift and right-side brake controls. Many bikes switched from right to left, including the Sportster and the Norton Commando. AMF's remedy was to continue using the existing engine cases and route the gear-shift linkage across the back of the engine, thus avoiding the expense of re-tooling. New cases were eventually fitted in 1977. Approximately 5,300 Sportsters were produced in 1975.
read Replace Sportster Fork Seals
1976 Sportster - Bicentennial Edition
To help celebrate America's 200th Birthday, Harley-Davidson offered special Bicentennial Edition models, with commemorative decals applied to the gas and oil tanks. Later in the year, Sportster models switched from Bendix to Keihin carburetors.
In an effort to re-capture some of its lost market, two new Sportster models were offered in 1977. The first was the XLT, set up in touring style with a thicker seat, touring handlebars, saddlebags, and windshield. It was also geared higher, and carried a larger 3.5 gallon tank. The XLT was not popular with buyers, nor was the other new model, the XLCR Cafe Racer.
Geroter Oil Pump
Redesigned engines cases for 1977 featured a new oil pump, which is not interchangeable with 1957-1976 models. Main bearings were also changed, also not interchangeable with earlier models.
read about Sportster Cafe Racer
Confederate Edition Sportster
In 1977, the Motor Company offered very limited "Confederate Edition" motorcycles. Essentially decals-only in difference from standard models, the "Stars and Bars" flag adorned gas tanks and fender. Production numbers were very low, with reportedly 299 Confederate Sportster XLs, 45 Sportster XLCHs, and 15 Sportster XLT models sold.
The factory brochure proclaimed the 1978 Sportster as the "quickest, most powerful, most agile yet." Electronic ignition and a solid-state voltage regulator first appeared this year, providing easier starting and less maintenance. The XLCR Cafe Racer was in its second and final year of full production.
Other Sportster models now benefited the Cafe Racer's dual-disc front brakes and cast aluminum wheels, as well as having Siamesed exhaust pipes, boosting torque and mid-range horsepower. Longer stroke rear shocks helped increase rider and passenger comfort.
75th Anniversary Edition
To commemorate Harley-Davidson's 75th year in production, a special-edition 1978 Sportster was offered, featuring midnight-black paint highlighted by gold trim, gold cast-aluminum wheels, and limited-edition anniversary graphics. Sales for 1978 topped 17,000 units, the highest in Ironhead Sportster history.
All Sportster models were upgraded to a new, stronger frame and swing-arm, derived from the XLCR. Valve guides were changed to cast-iron to provide better lubrication to the valve stems.
Also for 1979, the mechanical rear drum brake was replaced with a hydraulic disc brake. This would be the last year of the kick-start only Sportster. Only 141 XLCH models were sold.
Using the XLCR's frame, the new XLS model had cast wheels, extended front forks, 2-into-1 exhaust pipes and a 16" rear wheel. With a large, dual rear seat and short sissy bar, the XLS was decidedly un-Sportster like, and curiously named the "Roadster".
Sportster VIN Numbers
The Motor Company used several different VIN codes for XL models. A post-1970 Sportster VIN will start with a 3A or 4A. A Cafe Racer VIN will start with a 7F. An XLS Sportster VIN will start with a 4E.
Looking back over the decade, the Sportster had come a long way. It was still a great looking, powerful street-bike, and more reliable than ever. At 500 pounds and sporting a 59" wheelbase, cornering was not its strong suit, but a low center of gravity made the bike easy to manage, even when cruising slow. The softly sprung suspension gave a firm but comfortable ride at highway speeds.
read 1980-1985 Sportster History
A large percentage of old Harleys have been "customized" through the decades. Many good-intentioned riders built choppers through the seventies and eighties, cutting and raking necks and removing/throwing away good factory parts. This is why, when you find an old bike that's original or not that far off, the best thing to do is restore it correctly or consider selling it to someone who will.