Harleydavidson Engine Performance

Most Harley-Davidson motorcycles are powered by a V-twin engine.

Harley-Davidson motorcycles are generally designed as open road cruisers with massive two-cylinder V-twin engines. Harley-Davidson uses old-school engineering. The company equips its bikes with engines featuring a crankshaft with a single pin, and then has the two pistons connected to the pin via each piston’s connecting rods. This gives the bike its signature uneven throaty sound at idle that develops into a roar when the throttle is opened.


The look, sound and performance of the Harley-Davidson has remained consistent since the Milwaukee, Wisc.-based company’s infancy. It was a major supplier of military motorcycles during world wars I and II. Harley-Davidson stumbled badly when it attempted to compete with the lighter Japanese motorcycles in the 1970s, according to Powerpassion.nl. It fared worse when the company was sold to American Machinery and Foundry (AMF), which streamlined production, but also made inferior motorcycles compared to the Japanese imports. The company rebounded; it was sold in 1981 to a group of investors and the grandson of the company’s co-founder.

Engine Evolution

Harley-Davidson relied on the same engineering concept between 1936 and 2003 with the basic 45-degree, V-twin air-cooled motor. There are two engines that are relatively recent additions to the Harley-Davidson line. The Evolution made its debut in 1984 as a 1340cc model and continued as of 2010 with 883cc and 1200cc displacements. The Revolution engine was launched in 2001 and powers the Harley VSRC. The Revolution is a rare Harley 1130cc engine that is liquid-cooled instead of air-cooled. The 1584cc engine remains the standard cruiser engine.

Softail Performance

The 2010 Heritage Softail Classic pays homage to is roots with retro styling, but electronic sequential port fuel injection to deliver fuel to a counter-balanced twin cam V-twin 1584cc engine. Power is transmitted via a six-speed transmission. Wielding 92 foot-pounds of torque, the twisting force generated to give the bike its acceleration, the Heritage Softail achieves 35 mpg in city riding and 54 on the highway. It can comfortably hit 110 mph on the open road without much effort.

Comfort is Everything

The 2010 Road King FLHR also features a V-twin 1584cc engine to reach 110 mph, although it takes more effort than the Softail. Its fuel efficiency is virtually identical to the Softail’s, but offers just a tad more torque at 93 foot-pounds. The Road King‘s wheelbase is an inch shorter than the Softail at 63.5 inches, but weighs a hefty 775 lbs. compared with the Softail’s 730-lb. weight. The Road King‘s strength is that it can reach 70 mph on the highway effortlessly thanks to the six-speed transmission. But the Road King’s weight is its enemy because it labors at higher speeds.

Aggressive Sportster

The 2010 Harley-Davidson XR 1200 Sportster can trace its roots to dirt bike racing, but still sound like vintage Harley. The engine is a fuel-injected air-cooled 1200cc Evolution V-twin with torque rated at 74 foot-pounds. It obtains 38 mpg in city riding and 53 on the highway. Top speed is 125 mph, but it’s difficult to safely navigate that kind of speed on a relatively short bike with a 59.8-inch wheelbase and weighing in at only 562 lbs. Although it serves well as a cruiser, its dirt bike roots make it a better commuter.