Classic Motorcycle Build

Ironhead Sportster Projects

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.

classic motorcycle build

Flexibility of the compact V-twin and basic frame are nearly limitless.

A classic custom motorcycle is never out of date

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.

Ironhead Sportster Project

Many Sportster enthusiasts rate the 1965 XLCH as one of the best. 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)


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.

Ironhead transmission remove and install

Read: Sportster 4-Speed Transmission

Read: Sportster Transmission Remove and Install


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 install clutch

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.


Harley Sportster bendix drive

To replace a Bendix starter gear, read Replace Sportster Bendix Gear.


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).

1972 Harley Sportster ad

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.

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 slightly stronger than the earlier models.

Also in 1973, the Sportster's original 33.4mm front forks were replaced with 35mm forks.

replace fork seals Harley Sportster

Read: Replace Sportster Fork Seals


Disc Brakes

The Sportster front brake drum was upgraded to a single disc in 1973. Sportsters from 1973 through mid-1977 have the "pie-slice" brake caliper.

Ironhead Sportster caliper rebuild

Read: Rebuild 1973-1977 Sportster Caliper

Later models (1978-1983) have dual-disc front brakes.

1977 Harley Cafe Racer with dual disc brakes

Read: Rebuild Harley Dual Disc Calipers

rebuild Sportster brake master cylinder

Read: Rebuild Harley Master Cylinder


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.

1976 Sportster project

Read: 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. One of the harder parts to find are the rear foot controls.


Ironhead Carburetor Links

Linkert DC Carb Rebuild
Bendix Carburetor Rebuild
Install Mikuni Carb on Sportster
Tuning The S&S Super B
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 points ignition were replaced with a breakerless electronic type.

Eighties Ironheads

The 1980 through 1985 models were the most produced Ironhead Sportsters, so they are easiest to find and least expensive to buy. They also have a lot of nice upgrades from earlier models.

Read: Sportster History 1980-1985


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


Generator Charging Problems

A generator 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.

Read: Harley Generator - Repair or Replace?

Ironhead charging problems

Read: Install Cycle Electric Generator

If you're having charging problems with your Sportster's generator system, the least expensive solution is a generator to alternator swap. As an added bonus, your bike will lose several pounds of weight in the conversion.

Read: Ironhead Alternator Swap


Related Articles:

Electric Start Ironheads
Electrical Wiring for Motorcycles
AGM Motorcycle Battery Review
Basic Motorcycle Wiring
Convert Harley To Points Ignition


Ironhead Engine Articles

Ironhead Engine Build
Engine Case Prep
Ironhead Flywheel Rebuild
Ironhead Sportster Cylinders
Ironhead Top End Rebuild
Ironhead Rocker Box Assembly
Primary Chain Remove and Install
Remove/Install Sportster Cam Bushings
Install Sportster Cams
How To Adjust Ironhead Valves
Ironhead Bottom End Rebuild (1957-1976)
Ironhead Engine Assembly (1977-1985)
Replace Sportster Bendix Gear
Ironhead Special Tools

Along with more displacement, stroking an Ironhead engine will you get more power, along with lots of minor installation problems.

Read: Ironhead Stroker Build