V-Twins Motorcycle Engine - Exhaust Notes

Meet The Flockers

Cruiser riders like to think of themselves as independent, unique thinkers, but apparently that doesn't apply to their engine choices. When it comes to engine design, we are clearly stuck in a rut. Of the 105 bikes included in our Buyer's Guide, only five had more than two cylinders. Take away the two singles and you have 98 twins, 86 of them V-twins.

Those popular narrow-angle, tandem V-twins are a natural fit for motorcycles. Their triangular shape seems molded to the available space between the front wheel and the transmission and swingarm. They don't hang out the sides the way an across-the-frame multi might. This is why V-twins were favored in early motorcycles and why they became the classic motorcycle engine, especially in America. The V-twin's appearance and sound grew to be what people, or at least Americans, came to think of as "real" motorcycle engines.

However, as ingenuity and technology were brought to bear, tandem V-twins' functional success in motorcycles was matched and exceeded by other engine configurations. The potential advantages of twins-narrow cross-section, simplicity, lightness -are rarely exploited in cruisers. Many cruiser V-twins have wider cases than some inline-fours. Although a 90-degree V-twin is quite smooth, only Moto Guzzi uses one in its cruisers-and Guzzi turns it sideways in an arrangement that's functional but far from American tradition. Hidebound cruiser buyers have, of course, stayed away in droves.

The potential for simplicity has been somewhat lost as designers sought to overcome some of the V-twin's shortcomings. To overcome the vibration inherent in narrow-angle V-twins, cruiser builders have come up with a variety of technologies. Counterbalancers, involving additional drives and shafts in the crankcase, are most popular. Some engines use offset crankpins to get the smoothness of a 90-degree configuration with a narrower angle. But those don't sound like a single-crankpin design with the same angle and haven't been as successful. Yamaha has managed to smooth out the Road Star by using a heavy crankshaft.

V-twins are presumed to be torquier, with wider powerbands than other designs. Honda's Valkyrie, which uses six cylinders instead of two to make 1500cc, reveals that is a myth. The Valkyrie is the only cruiser I've ridden that will pull willingly and smoothly from below 20 mph in top gear. It has a top-gear speed range spanning about 120 mph. V-twins with comparable displacement typically have a much smaller speed range in top gear. Even if you're feeling shiftless, a V-twin isn't necessarily the remedy.

Obviously, we Americans think narrow-angle tandem V-twins look great in motorcycles, though parallel twins and V4s dress the engine bay just as neatly and are actually a bit simpler to manufacture. Triumph continues to enjoy success with its Bonneville vertical twins, and the design follows British tradition. But its sales are modest by V-twin standards. BMW's opposed-twin (think of it as a 180-degree V-twin if you like) is smooth, but few American cruiser buyers cared. After an initial surge of sales to early adopters, BMW sales tapered off. American buyers once regarded Honda's V4-powered Magna as one of the sweetest cruisers out there (as evidenced by sales), but a few years ago, something soured. Maybe it was the fact that Honda hadn't changed anything except color for a decade, but it's no longer in the line despite the fact that it outperformed every V-twin except Harley's V-Rod. Yamaha shows the range that multis can span, with its tractable Royal Star tourers and butt-kicking V-Max, all built on the same basic V4 design. The formula for the Royal Star touring machines works quite nicely, and the new Tour Deluxe is a traveling bike I'd enjoy owning. However, V-twin-flockers may keep it from being the hit it should be.

If you are married to the style or sound of a narrow-angle V-twin, you severely limit the range of motorcycles-and their capabilities-you are likely to buy. Personally, I like the sounds of other bikes, especially those with an out-of-the-ordinary cadence, like triples, V4s and sixes. Unfortunately, the lemming-like march to V-twins means some of the best motorcycles in cruising have been dropped and manufacturers will probably be reluctant to devote resources to developing motorcycles with other, nontraditional engine configurations. Unless cruiser buyers step out of the V-twin box, our choices are likely to continue to narrow. Your next bike-and my next test bike-is likely to be another variation on the same old thing.-Art Friedman

Send e-mail to Friedman at ArtoftheMotorcycle@hotmail.com.