Classic Motorcycle Build

Harley FX Models

Article by Mark Trotta

Designed by Willie G. Davidson (grandson of company co-founder William A. Davidson), the Harley FX Super-Glide combined the lighter, thinner front-end of the Sportster with a Big-Twin frame and motor. At 560 pounds, it was 150 pounds lighter than an FL model, and 60 pounds heavier than a Sportster. The 1971 Super-Glide was the first of the Harley FX models.

Harley FX models

The first-year Super-Glide featured a fiberglass boat-tail seat/fender combo that survived only one year. The 1972 model looked much cleaner, with a banana seat and Sportster-style rear fender, combined with "Fat-Bob" gas tanks and dash unit from the FL. Although not a big seller at the time, the Super Glide is considered to be the first factory custom motorcycle.

Early Super Glide Forks

Super Glide fork tubes where shared with early Sportsters, which were taken from the Harley K-model. The 33.4mm diameter tubes looked pretty spindly attached to a Big-Twin frame. In 1973, disc brakes became standard, and the fork tube diameters were increased to 35mm, manufactured first by Kayaba and then Showa (both Japanese companies).

Early 35mm forks have the single "pie-slice" brake caliper, later models have dual-disc calipers.

Harley FX caliper rebuild

Read: 1974-1977 Harley FX Caliper Rebuild

1974 Super Glide

In it's third year of production, the FX was given a smaller, one-piece three-gallon gas tank instead of the larger FL Fat-Bob tanks. This made the bike narrower and a little easier to ride aggressively. The Super-Glide FX was joined by the FXE, an electric-start version. Both models had the one-piece gas tank

Harley FX models

The year 1974 saw FL Touring models switching from a Bendix carburetor to a Keihin, while the Harley FX models continued using the Bendix carb. The FXE began outselling the FX, then out-selling the FLH touring bike, becoming the most popular Harley Big-Twin model.

Read: Bendix Carburetor Rebuild

Harley Big-Twin bikes came equipped with Bendix carbs from 1971 through 1975. In 1974, Harley FL Touring models switched from Bendix carburetors to Keihin, while the FX models continued using the Bendix carb.

Harley-Davidson Low Rider

In 1977, the FXS Low Rider was introduced, featuring a low 26-inch seat height, shorter rear shocks, alloy wheels front and rear, twin disc-brakes in front, and extended forks with a 32-degree rake. The Fat-Bob tanks returned, but with a new dashboard containing a speedometer and tachometer.

Harley FX Shovelhead history

Unlike the Super Glide, the Low Rider was an instant hit, outselling other Harley Big Twins in it's first full year of production. All three FX models now sported Fat-Bob tanks, with their own center divider.

74ci vs 80ci Shovelhead

From 1966 to 1977, the Shovelhead motor displaced 1200cc. The cylinders carried a 3.44" bore with a rod-stroke of 3.97", making 74 cubic-inches. During production of the 1978 model year, engine size was increased to 1340cc (80 cubic-inches) and was available optionally with Harley's FL Big-Twin bikes. The larger engine was offered on Harley FX models in 1979.

Harley-Davidson Shovelhead history

Whereas the 74ci motor was designed to run on premium leaded fuel, the 80ci motor was designed to run on premium unleaded. Externally, the only difference between the two big-twins was the 80ci had one less fin on the cylinder.

Shovelhead Cylinder Heads

A cylinder head change was seen in mid-1978. Early Shovelhead motors had a small-lip o-ring to seal the intake manifold to the cylinder head. Starting in mid-1978, the o-ring was replaced with a flat band with no lip.

1979 Harley-Davidson FX Models

The kickstart-only FX was discontinued in 1979. In that same year, the FXEF Fat Bob was introduced, offered with either cast or spoked wheels, and with either the 74 or 80ci motor.

Harley Wide Glide

Based on the Low Rider, the Harley FXWG Wide Glide first appeared in 1980. Wide Glide models featured wide chrome front forks with a 21" front tire, disc front brakes, and a flame pattern painted on the gas tank. In addition to the FXWG models, Wide Glide front ends also came on 1980-1983 FWDG Dyna series.

Harley FX model history

Read: Wide Glide Front-End Conversion

1980-1982 Harley FXB Sturgis

Painted black with red trim, the short-lived Sturgis FXB featured a king/queen seat, belt-drive, and thick-spoked wheels. The fuel tank featured a speedometer, tachometer, and matching filler caps. A two-inch fork extension gave it a mild "chopper" look.

Harley FX Shovelhead history

The Harley Sturgis was named after the annual motorcycle rally held in South Dakota. Originally produced only two years, the Sturgis would re-appear in 1991.

Harley FXR (1982-1994)

Introduced in 1982, the Super Glide II (FXR) differed from the existing FX models in many ways. Where other FX models had solid engine mounting and a four-speed transmission, the FXR shared the rubber-mounted engine and new five-speed transmission with FLT Tour Glide. The easiest way to recognize an FXR from other FX models is by the triangle-shaped side cover.

air-powered motorcycle lift stand

Read: Best Motorcycle Lift Stand For Home Garage

Only two model year FXR's (1982-1983) were equipped with the Shovelhead engine, subsequent models (1984-1994) were powered by the Evolution motor. The FXR handled well and was fast. It also had less mechanical problems than previous FX models, which helped the bad reputation all Harley-Davidsons suffered during the seventies.

Chain-Drive to Belt-Drive

In 1983, the Low Rider was converted from chain-drive to belt-drive and given the designation FXSB. Introduced this year was the FXDG Disc Glide, featuring a disc-type rear wheel instead of the wire-spoked wheel of the Super Glide or the solid-spoked wheel of the Low Rider. The FXB model was discontinued.

Harley FX Models

Harley FX Models history

Harley Shovelhead VIN Numbers

From 1966 to 1969, the only VIN is on the engine number located on left case. There were no frame numbers until the 1970 model year. The first two numbers are the year and the letters (up to four) are the model code, example, FL or FH. The last numbers are the production number.

Up until 1969, engine VIN numbers usually started at 1000 each new year. Harley-Davidson didn't necessarily assemble machines in exact numerical (serial number) order. Sometimes engines were held back due to one reason or another, so it's possible that an engine with a numerically lower VIN number may have reached the final assembly line after engines which had a numerically higher VIN number.

Harley-Davidson FX Shovelhead history

From 1970 to 1980, matching VIN numbers appear on both frame and engine. All Harley FX models should have matching frame and engine numbers if the bike is all original.

In an attempt to curtail theft, the Motor Company used different frame and engine numbers on some 1979 models. The frame numbers didn't match the number stamped on the engines. The first two digits remained the model code.

From 1981 to 1983, a 17-digit VIN appears on the frame, and the engine had a partial VIN.

Harley FX Models history


DIY Harley Engine Stand

Here's an engine stand I welded up - it makes working on the motor a lot easier. It will accept Harley 45" Flatheads and Big-Twins 1936 to 1999 (Knucklehead, Panhead, Shovelhead, and aftermarket engines). Sportster engines are different and won't fit.

Harley engine stand

Read: DIY Harley Engine Stand


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