What is this “aftermarket” we hear so much about? To state the obvious, the “market” is the Harley dealer and all the accessories the Milwaukee folk can dream of, and the “after” consists of hundreds, if not thousands, of companies that build stuff for Harleys that Harley owners can buy. Or, in other words, the trinkets you can spend your money on after you have bought your Harley-Davidson.
If you stacked all the aftermarket catalogues for 2008 in a pile, it would probably stand over 5 feet tall. Some are skinny, some are huge, running way over a thousand pages. What the Sears & Roebuck catalogue was to the rural citizen 80 years ago, these fat books are to the present-day Harley buff.
I’m not going to talk about the bling factor in the aftermarket, the pretty stuff, but the purported performance items, which cover everything from programmable black boxes to 131-cubic-inch engines. Wowzer, 131 inches! That may be stretching practicality a tad too much, but think of the fun you could have on your daily commute. It took 40 years for Harley to enlarge that 74-inch engine to 80 inches, and now, 30 years later, we have the Milwaukee-built 110-incher, but the aftermarket makes them bigger and bigger and bigger.
These engines, whether made by Custom Chrome or Zipper’s, are all clones of the Evo and Twin Cam motors, and before the cloners start sending me hate mail, let me say there is nothing wrong with cloning, as it only means the aftermarket engine is based on the same design as a Harley motor.
How did this Harley aftermarket become so strong? Probably because the hardcore of the Harley market is based on an appeal to old-fashioned technology, and your stock Hog is pretty much of a porker when it comes to power. It has been noted more than once that Harley consciously produces rather low-powered engines that The Company would like to hot up for you—for a price. And the aftermarket will happily take that even further—for a price. But most riders are advised to do their homework before spending a lot of money on performance products; after all, it ain’t as easy as it looks.
All this relates to the fact that the basic engine, an OHV, air-cooled, 45-degree V-twin, has been on the market since 1936, and it is both popular and slow. You want modern, get a V-Rod. You want a 96-cubic-inch engine that puts out some 60-plus horsepower at the rear wheel (and close to 80 pounds-feet of torque, the really useful power), think Big Twin.
Nothing wrong with those figures, as most riders rarely need more than 60 horses unless they’re two-up and overtaking a double semi on a steep grade in the mountains. In truth, much of the hop-up business is for bragging rights, and dyno ratings, with mobile dynos appearing at most rallies. While there is a lot of honestly good go-fast equipment in the aftermarket, there is also a lot of junk. Plus, a ham-handed home mechanic can make even good stuff worthless.
The most common aftermarket purchase is an exhaust system. It’s relatively inexpensive, easy to put on (perhaps), and you like to think this will set your Twin Cam apart from several hundred thousand others. A few (most?) are too damned loud and should be illegal, but most are in there for the styling, not the noise. Many claim to increase horsepower; just make sure that your black box, fuel-injection system and air cleaner are all in sync with your new pipes. A manufacturer likes to be part of the header/muffler act because the profit margin is pretty good, which is why so many are involved, from Arlen Ness to Vance & Hines, and probably another 50 or 60 companies making pipes.
My local aftermarket shop in Atascadero, California, Two Wheels, is very genteel, with a table and umbrella set up outside, where owner Greg likes to hold court. When the brown truck arrives, the UPS driver often hauls out a really big box, which looks as though it will weigh half a ton. Except it doesn’t, because all it has inside is an exhaust system. As Greg likes to say, “There are a lot of bikers out there who like to think they’re going faster when they make a lot of noise; they don’t like it when I tell them they’re not.”
All this go-fast equipment can get real complicated real quick. Order up an exhaust system for a carbureted Twin Cam and if you want to get the best out of it you’ll need to be futzing with carb settings and air cleaners. Fuel injection? You can buy a dynamometer (very expensive!), or rent time on one (much cheaper), and acquire the extensive computer skills to reprogram your black box, or more likely get a Power Commander that takes a bit of the brainstrain out of the equation. In truth, that is a really complicated equation, balancing what goes into the engine with what comes out, and it is way more than I want to deal with. If I really want my motor to put out more power, I’ll let an expert do the work. That’s money well spent.
In between the intake and exhaust are the cylinders and heads. Put in some 11:1 pistons and a pair of hemi four-valve heads, and what do you have? Well, 11:1 is not too reliable for street use, as the temperature inside those combustion chambers can easily arrive at meltdown status. Four-valve heads are very tricky, used as far back as 1916 on Harley’s race bikes. Quad valves are most often used with high-revving engines like the V-Rod’s, but a Big Twin is not designed to be a revver. On the other hand, while RPM’s four-valve heads are a bit pricey they are good for boasting rights, especially when talking to the ignorant.
What may be the most absurd hop-up gizmo—by my modest reckoning—is a $3,400 kit that includes a pair of twin-throat Weber carburetors, one coming out of each side of the engine. That’s like water-boarding the engine, and I can imagine pools of gas forming on the cylinder tops.
More horsepower at the crank means you may want to rethink the primary and clutch. An open-belt primary always provokes a lot of conversation; just make sure the curious children stay away. There is nothing really romantic about a clutch, but a stock clutch won’t last long if there is a substantial power increase, so the aftermarket catalogues offer many alternatives.
Which leads to the transmission. Harley six-speeds are pretty good, but on the Big Twin the problem for the stylish customizer is being able to move the final belt drive to allow the use of a fat tire, like a 4.00. You can buy offset kits to allow you to continue using the left-side belt, but they only go so far, and then you have the tedious process of moving the engine itself to the side. Which often prompts a Harley to lay down on its left side. Which is why right-side-drive trannies are getting so popular.
Few riders who are entranced by aftermarket hype actually sit down to figure out how much each extra horsepower is costing them; that would take the fun out of it. As for me, I’ll rely on our own Joe Minton to give me directions, because he’s done all his homework.
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