Common Tread

Moto 101: Learning your Harley ABCs

Apr 02, 2013

FLHTCUWhat?

Harley-Davidson model names sometimes look like a foreign language. Or code. But there is some rationale behind all that alphabet soup.

Here's a quick and dirty crash course in H-D nomenclature. This is not comprehensive or complete. Factory records are even spotty from some time periods (there was a big fire in the 1950s), and Harley built and did strange stuff over the years. Respected Harley historians aren’t even in agreement on many aspects of things, especially regarding the early bikes. Remember, the original shop in Milwaukee was akin to your modern custom bike shop. It was just a few fellows wrenching away on bikes being built on wooden tables.

Also, there are thousands of common H-D nicknames for stuff. If you don’t know what a mousetrap, ratchet lid, Pan-Shovel, or electric foot are, it’s OK. You’ll get there.

Super-glossed-over early-ish Harley-Davidson history

Harley made some items you might not immediately associate with their brand. Thumpers. Peashooter flat-trackers. A BMW boxer copy. They licensed Aermacchi small-displacement bikes, which were sold as H-D products. They built snowmobiles and golf carts and even fishing boats. Harley even had project in the 1980s with the code name "Nova," which was a liquid-cooled V-4.

Not all of this stuff was bad ideas and psychedelic drugs. A lot of these innovations paved the way in motorcycling. They began using conventional hydraulic front ends on the Hydra-Glide in 1949. Bikes got suspension at both ends in 1958 on the Duo-Glide. The Sportster was the BMW S 1000 RR of its day. It was a performance contender, a hot bike and a research test bed. The 1965 Electra Glide was the first common H-D to receive electric starting. Take a moment to think about that. In 1963, you could buy a premium, top-line touring bike, and you would be kick-starting its cantankerous ass to life.

None of this is particularly important, but you need to know that Harley was making bikes from the very beginning of motorized history, and they were crude and rough, made to last even if they were not too refined. Harleys are infinitely rebuildable right up through the Evo engine, and usually, the value they command makes it worthwhile to do so. The proliferation of Sportster parts alone speaks to the vastness of this demand. If you see an old Shovel on the road, chances are it’s on its third overbore, and probably has had six owners.

Now, a fast breakdown of the stupid letter system must acknowledge how difficult it is to follow things. The first two or three letters in air-cooled Harley letter codes may have referred to the series, size, and compression of the engine. Or maybe the chassis. Or nowadays, maybe something else. So an EL would have been a high-compression (L), 61-inch OHV (E) model. A VLH was an 80-inch (H), high compression (L) side-valve with total-loss oiling (V). Sometimes, there were letters that weren't in the official model code. (An FLS, for instance, was a motorcycle that was equipped with a sidecar from the factory, but the VIN would only indicate it as "FL.") In the 1950s, an XL was the new Sportster (all were high-compression, hence the L), and FL or FLH was a Big Twin 74 ci engine with either high or low compression. Though displacement and valve arrangement has changed, "F" sort of settled in as the Big Twin letter code of choice. And while we're on the topic of confusing things, letters could also describe other parts of the bike, like the chassis. A G, for instance, was a three-wheeled Servi-Car with a 45 ci flathead engine, but that same engine stuck into a two-wheeler chassis was a W.

For instance, in 1971 the Super Glide was rolled out, dubbed the FX. F indicated a Big Twin engine, but the X designated the bike's narrow front end that came from the unitized-engine Sportster (X, remember?).

Still following along? My head hurts. So...

FL (big engine, fat front tire and wider fork) plus XL (Sportster, little unit engine) equals FX (Super Glide — big engine, sporty-handling front end). Those basic designations still survive today, for the most part, with some other suffixes tacked on for good measure.

Another character was sometimes added was one differentiating the frame, as Harley started using different ones. (And sometimes a fourth character, too, depending what frame is used, like the ST designation, used for most Softails, but sometimes they are simply an “S,” like in the FLS Softail Slim... I hate you, Harley.) Prior to the 1980s, the big bikes all used the same frames. But after the FXR, Softail, Touring, Dyna, and other frames were developed, there had to be a way of differentiating a Big Twin engine in one chassis from a Big Twin engine in another.

Touring frames with fork-mounted fairings currently begin with FLHT, and Touring frames with frame-mounted fairings are FLT. Dynas were D frames. Rockers, a crazy wide-tire variation of the Softail, were given the letters FXCW. Rubber-mounted Big Twins with narrow frames became the FXR we previously mentioned. Designed by a young Erik Buell, they are easily picked out by a metric-style “triangle” of frame tubes joining under the saddle. 

The rest of the letters after the first two, three or four represent options, but they are inconsistent. D, for instance, could be "Deuce" or "Dyna." Some common ones are:

  • SS: Springer Softail
  • SC: Springer Classic
  • WG: Wide Glide
  • FB: Fat Boy
  • SE: Screamin’ Eagle
  • B: Belt

Current model names and letters

This section is sort of bleed-over from the previous section. It’s born from the wild proliferation of options as customers began demanding more and more crazy stuff. Blame it on the 1990s.

Harley let the letter thing get out of control. Now they try to just use model names in the showroom, but the letters are still there. Old Harley guys ignore them because they make no sense to normal, breathing humans. Hence, if you can figure out really fast that an FLHTCUTG is an Electra Glide Trike, you’ll look like a genius.

At the time this has been authored, there are five model families within H-D: Touring, Sportster, Dyna, Softail and V-Rod.

Let’s start with the easy one. Sportsters always start with “XL.” There are other letters that can follow, and numbers sometimes indicating displacement, but just remember that an XL is a Sporty. Sporties have unitized motors. To this day, The Sporty has four cams, and that atypical-for-H-D setup means that the pushrod tubes run parallel to one another. You can pick a Sportster engine out a mile away because of it. Done.

Next are the Harley Touring bikes. These bikes all have heavy frames, bags, and either 16-inch or 17-inch wheels on non-CVO models. The really narrow, big diameter tires won't be seen on these bikes.

(A brief aside: CVO is “Custom Vehicle Operations.” It is the performance division of H-D. Usually, bigger engines that will later appear in production bikes are showcased here. Crazy paint is the norm, and hot rod parts and trick wheels are to be found. They are pricey and limited numbers are produced each year. The letter code for these is usually SE.)

There are really only three types of touring bikes: those with batwing fairings (named, duh, because it looks like a bat wing), those with windshields, and those with sharknose fairings. (These look like a, uh, nose. Like, on a shark.) Batwings mount to the forks, sharknoses mount to the frame, and I assume you all know what a Plexiglass windshield looks like. If you wiggle the bars and the headlight moves, it’s a batwing. If you move the bars and the headlight points down the road still, it’s a sharknose and a Road Glide, one and the same. If it is a Touring bike with just a windshield, it’s a Road King (FLHR). Road Glides with the frame-mounted fairing start with model code FLTR, while every other Touring bike is an FLHT.

Moving right along, we now have Softails. They’re easy to spot. They have a hidden rear suspension that attempts to mimic a rigid motorcycle with an unsprung rear, but they really are suspended. Popular ones include the Heritage Softail, the Fat Boy, and the Night Train. They come in two main varieties: FXST Softails with a narrow, large diameter front tire and FLST Softails with a wider, smaller diameter front tire.

Some Softails, like everything in this alphabet soup, buck the trend — the Softail Slim, for instance, is an FLS. Why? Because it’s Harley; they can do whatever they want. FLST was already taken, and to start stacking more letters in was going to be ridiculous. The Blackline is the same way. It’s an FXS. Why? FXST was taken, and to use a different name, they’d have to make alphabet soup. To make matters more confusing, before the ST (Softail) frame existed, an FX-framed bike was a Super Glide! So, if a rookie tells you he has an FXS, it might be a Shovelhead with exposed rear shocks, or it could be a Twin Cam with hidden rear suspension.

Incidentally, if anyone tells you they have a “Springer,” the Softail is the only modern bike Harley put springer front ends on. They will fit on other stuff and riders swap them onto all types of things... but H-D only ever put them on Softies.

There’s one caveat here in the Softail category: Heritage Softails. Man, they look a lot like a Road King. They’re patterned, really, after an old Hydra-Glide, meant to look suspended in front, and rigid in the back. Road Kings are patterned after the old Duo-Glide. They’re not trying to trick you into thinking that they don’t have rear shocks.

Well heck, this is easy, right?

Next up are V-Rods. With liquid-cooled engines, they're unlike any traditional Harleys. The letter code on all of them will go VRSCsomethingsomething.

Finally, we have the Harley Dyna. The cheapest way to get into a Big Twin, this model is easily distinguished by its exposed rear shocks and narrow front ends. They all start with FXD, with the recent exception of the new Switchback, which is an FLD because it has the little front wheel and is the only Dyna to have the wide-ish Touring forks. (It's like a scaled-down Touring bike.)

So you're probably still confused, and you have a right to be. Much like learning English, there are so many exceptions you have to wonder how anyone learns the rules! It does sort of come if you stick with it a bit, but yes, it's a little dizzying.

Harley engine names

As if that wasn't enough of a pain, Harleys are also often referred to by their powerplant. The names are not separate from the bikes, they’re in conjunction with them. Realistically, you could refer to your bike as a Blockhead, a Dyna, a Wide Glide, an FXDWG, a Big Twin, or a Harley, and still be pretty spot on with all of it. Note that these terms are not official Harley ones — but that doesn't change the fact that they're unbelievably common and you might want a lesson on them.

Engines were usually nicknamed due to the shape of their rocker box covers. The practice stuck, even when a bike name would have been more helpful, but people do what people do. Most older Harleys wind up getting cut up into Frankenbikes, so it at least gives people an idea what era the bike came from. Basically, there are two groups: Big Twins, and Everything Else. Big Twins have separate transmission assemblies and left-side final drive. Here are the notable players in the Everything Else category:

  • 45 (Flathead), 1929 to 1973. Found in motorcycles until 1952, and then its use was relegated to the Servi-Car (letter code G), a little run-around trike originally meant for automobile dealers, but later outfitted for all sorts of urban delivery chores. Not usually lumped in with big twins. Also not to be confused with Big Twin flathead. This one’s kind of a freak, don’t worry about seeing one, they’re pretty rare and slower than all bejesus (50 mph on a good day with a downhill stretch and a tailwind). Oddly, they were pretty much unchanged up until the 1970s, so you were really riding history, even back then.
  • Ironhead, 1957-85. Found only in XL models (Sportsters). Motor is different from big twins in a variety of ways: four cams instead of one, and it is unitized (transmission and motor are all in the same casting). It’s easy to pick these out. The pushrod tubes are parallel to each other. Existed in 900 cc and 1000 cc versions.
  • Evo (Evolution) Sportster, 1986-present. Sportster only. Comes in 883 cc and 1200 cc versions.

Here are the notable Big Twins (non-unit motors):

  • Atmospheric engine, 1909-1911. 49 ci.
  • F-head, 1911-1929. Available in 61 ci and 74 ci.
  • Flathead, 1930-48. It was made in 74 cubic inches of displacement and, later, 80 ci.
  • Knucklehead, 1936-47. It was first 61 ci and, later, 74 ci.
  • Panhead, 1948-65. Made in 61 ci and 74 ci variants.
  • Shovelhead, 1966-84. It was 74 ci and, later, 80 ci. A word of note: Shovels from 1966-69 were made with Panhead-like lower ends. They have a flat right side like the earlier Pans and Knuckles, and are commonly called Pan-Shovels or "slabside" Shovels. The later Shovels are "cone" Shovels due to the shape of the ignition "nosecone" on the right side of the engine.
  • Blockhead, 1984-99. All Blockheads are 80 ci. A word of note: Also called Evolution or Evo, this engine is not to be confused with the Sportster Evo. Same name, different engine. Also know the "Blockhead" name never caught on as well as the earlier engines.
  • Twin Cam, 1999-2017. 88 ci, 96 ci, 103 ci, and 110 ci versions, as well as a 120 ci variant sold as a crate engine. Also called the Fathead by a very few folks, this differed from all previous OHV Big Twins by having more than one camshaft in the engine. 
  • Milwaukee-Eight, 2016-present. Produced in 107 ci, 114 ci displacements.