Classic Motorcycle Build

Ironhead Sportster Projects

Article by Mark Trotta

Over the last 60 years, Ironhead Sportsters have been the basis for choppers, bobbers, cafe racers, drag bikes, flat trackers, scramblers, hill-climbers, fully-faired track bikes, and even trikes. Flexibility of the compact V-twin and basic frame are nearly limitless.

A classic custom motorcycle is never out of date

My first motorcycle was a 1972 Sportster, which I bought wrecked in 1981. It was the only way I could afford the bike I wanted, but six months and $500 later, I was riding. I rode this bike for 13 years.

Best Year Ironhead Sportster

No model years are really better than others for a project bike, but certain year Sportsters may be more desirable for one reason or another. The 900cc Ironheads from the late fifties and early sixties were certainly the coolest looking in stock trim. These early Sportsters are much harder to come by, simply because less where made (ie, less than 2,000 total in 1962).

Early Sportsters equipped with magneto ignitions, 6-volt electrics, and solid-mount engines are not for everyone, but when left factory original or restored correctly, are worth quite a bit more than later models.

1965 Sportster Project

Many classic bike enthusiasts believe that the 1965 XLCH is the ultimate Sportster. It was the first year of 12-volt electrics, and had the wider front drum that came out the year before. It was also the last year for the DC Linkert carb and the "horseshoe" oil tank.

From 1957 to 1966, all Sportster models had the same frame and engine cases. To accommodate a bigger battery box and electric starter, the 1967 XLH received a new frame and redesigned engine cases. This was the first Sportster with electric start.

Last Real XLCH

Up through 1969, the XLCH Sportster had the early, shorter frame, so 1969 is considered the last "real" XLCH. All Sportster models from 1970 through 1977 would use same, longer frame.

In 1970, Harley-Davidson started stamping corresponding VIN numbers into both engines and frames. Before this, only the engines had VIN numbers, making early engines easy to swap in and out of whatever frame you choose.

1971 Sportster

The last year of the 900cc Ironhead engine was 1971, and it was the first year of new engine cases. The external distributor was moved from the top of the right-side engine case to inside the engine 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 final year.

Read: Sportster History (1967-1979)

Sportsters from 1973 through 1977 have the "pie-slice" brake caliper, later models have better-stopping dual-disc front brakes.

Sportster caliper rebuild

Dry-Clutch vs Wet-Clutch

A dry clutch is not spinning in engine oil, which causes less drag and robs less power than a wet clutch does. Wet clutches are quieter, but a harder pull at the clutch lever.

Ironhead Sportster with clutch assembly reinstalled

Read: Sportster Clutch Remove and Install (1971-1984)

Sportsters were converted to a wet clutch setup in 1971. As its name implies, the wet clutch sits in oil, the earlier dry clutch (1957-1970) does not.

Unit Transmission

Unlike Harley Big-Twins, you can't ignore the transmission when doing bottom end work on a Sportster engine. The transmission is housed inside the engine cases, so at a minimum you'll at least need to know how to remove and install it.

ironhead-transmission remove and install

Read: Sportster 4-Speed Transmission

1000cc Sportster

To keep up with the litre-bikes that Japan was offering, a bump in motor size was seen in 1972. Boring the cylinders 3/16" brought displacement from 883cc to 997.3cc (advertised as 1000cc).

The increase from 900cc to 1000cc also gave a more optimum bore-to-stroke ratio, resulting in a slightly 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 was easily gained.

1972 XLCH Sportster image

In 1973, the speedometer drive was moved from the bottom of the engine case to the front wheel. This allowed Harley to put some extra meat in the right side of the transmission area where the drive used to be. Because of this, 1973-up Sportster engine cases are stronger than the earlier models.

Also in 1973, a change from front brake drum to front disc was seen. In 1974, the 1000cc cylinders were stronger, and was also the last year for the shifter on the right side.

Right-Side to Left-Side Shift

The two years that Sportsters had the crossover shaft to make them left-side shift (1975-1976) makes them harder to find parts for. I've read that some riders had issues with these bikes, but I had no problems at all shifting or braking my 1976 Sportster.

Read: 1976 Sportster Project

1976 Sportster project

Sportster Cafe Racer

Produced for two years only (1977-1978), the XLCR Cafe Racer sported a new frame, front bikini fairing, four-gallon gas tank, and fiberglass rear tail section. Foot controls were mounted further back, and low handlebars allowed the rider lean forward into a "racer tuck".

1977 Harley-Davidson XLCR Cafe Racer

The Sportster Cafe Racer was offered in black only, with wrinkle-black engine paint and black Siamesed exhaust pipes which exited left and right. The exhaust was a departure from past Sportster models, but added a solid five-horsepower gain in performance. Unlike earlier Sportster frames, the XLCR frames have room for improvement, particularly when front and rear shocks are upgraded.

Cafe Racer Build

If you want to build an XLCR replica, the best bike to start with is a 1979-1980-1981 Sportster. These frames are basically the same as the factory Cafe Racer, as is the 1000cc motor.

Specific XLCR parts such as the seat, exhaust, headlight mount, and fairing are available either used or reproduction. The hardest part to find will be rear foot controls.

best carb for Ironhead

Read: Best Carburetor For Ironhead Sportster

1979 Sportster

In 1979, all Sportster models were upgraded to a new, stronger frame and swing-arm, derived from the XLCR. Some feel that the new frame took away the classic Sportster look, but it was lighter and made for a better handling bike. Also for 1979, the mechanical rear drum brake was replaced with a hydraulic disc brake, and the breaker-points ignition were replaced with a Prestolite breakerless electronic type.

The 1980-1985 models are the most common Ironhead Sportsters; they are easiest to find and least expensive to buy.

Read: Sportster History 1980-1985

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.

Ironhead charging problems

Read: Harley Generator - Repair or Replace?

Early Sportster models (1957-1966) were kickstart only. From 1967 until production's end in 1985, Ironhead Sportsters saw three types of electric starter motors; Prestolite, Hitachi, and Nippodenso.

Sportster Hitachi starter

Read: Electric Start Ironheads

Hardtail Sportster Build

Originally, all motorcycles were hardtails, and since there are no rear suspension components, a hardtail frame is much lighter than a conventional swing-arm frame. They are also easier and cheaper to construct, due to their simplicity. Many purists believe that with the absence of rear suspension, road vibrations become part of the experience, and the rider truly becomes part of the road.

Hardtail Sportster build

Building an Ironhead chopper is pretty simple. Unlike Big-Twin Harleys, there is no separate transmission that needs to be aligned. However, the rear-wheel chain sprocket needs to be lined up with the engine sprocket. The only way to do this is the trial and error method of adding/removing axle spacers on either side of the rear wheel.

Read: Hardtail Ironhead Build

An essential part of building any sort of chopper, bobber, or cafe racer, is getting rid of unnecessary items. This includes trimming down electrical parts, such as signals, gauges, relays and switches.

Read: Custom Bike Electrical and Wiring

Replacement Parts For Ironheads

Beware of imported low quality parts. The market is saturated with cheap Chinese and Taiwan-made parts, which are of low quality. Several Japanese manufacturers offer parts which are a better quality. U.S. companies like S&S offer quality parts, but not for all year Sportsters.

An Ironhead Sportster project may not be right for you. But if you don't mind working on your own bike and enjoy a challenge, it's a good choice for a classic motorcycle build.

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Ironhead Sportster project

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