Harley FX Models
Designed by Willie G. Davidson (grandson of 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 an XL model. The 1971 Super-Glide was the first of the 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 an FL 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).
Read: Replace Fork Seals
Early 35mm forks have the single "pie-slice" brake caliper, later models have dual-disc calipers.
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, which made the machine narrower and slightly 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 instead of the larger FL Fat-Bob tanks.
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 out-selling the FX, then out-selling the FLH touring bike, becoming the most popular Harley Big-Twin.
Harley Big-Twin models 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.
Read: Bendix Carburetor Rebuild
Harley-Davidson Low Rider
In 1977, the FXS Low Rider was introduced, sporting short rear shocks, alloy wheels front and rear, twin disc-brakes in front, extended forks with a 32-degree rake, and a low 26-inch seat height. The Fat-Bob tanks returned, but with a new dashboard containing a speedometer and tachometer.
Unlike the Super Glide, the Low Rider was an instant hit, outselling other Harley-Davidson models in it's first full year of production. All three FX models now had Fat-Bob tanks, with their own center divider.
Read: Remove and Install Harley Bendix Gear
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.
Whereas the 74ci motor was designed to run on premium leaded fuel, the 80ci motor was designed to run on premium unleaded. The 74" and 80" would use the same cylinders, but the 80" would be bored out to the larger size. 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 base, 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. A 1979 Low Rider in metalflake silver with black trim was a sharp-looking bike.
Harley Wide Glide
The Harley FXWG Wide Glide, based on the Low Rider, 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.
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, dual primary and secondary belts, and thick-spoked wheels. The fuel tank featured a speedometer, tachometer, and matching filler caps. A two-inch extension of the front forks gave it a "chopper" look.
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.
Read: Best Motorcycle Lift Stand For Home Garage
Only two model year FXR's (1982-1983) were equipped with the Shovelhead engine, models from 1984 through 1994 had the Evolution motor. The FXR handled well and was fast. It also had less mechanical problems than previous FX models, which helped repair the bad reputation all Harley-Davidsons suffered from 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
- FXSB Low Rider
- FXE Super Glide
- FXR Super Glide
- FXRS Super Glide
- FXRT Tour Glide
- FXWG Wide Glide
- FXDG Disc Glide
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.
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.
A large percentage of classic Harleys have been "customized" through the decades. Many good-intentioned riders built choppers through the seventies, cutting and raking necks and removing/throwing away good factory parts. This is why, when you stumble across an old bike that's original or not that far off, the best thing to do is restore it right or consider selling it to someone who will.