The seven main reasons why Harley-Davidson motorcycles have low horsepower figures are as follows:
- Harleys are built for cruising
- Harleys are tuned for torque rather than HP
- Traditional V-twin engine architecture
- Air-cooled and carbureted engines
- Low engine RPMs
- EPA regulations
- Room for modifications
Let’s get down to the nitty-gritty and talk about these in detail!
Do Harleys Have Less Horsepower Compared to Other Bikes?
Let’s face it, Harley-Davidson motorcycles have much lower HP figures than other motorcycles. Most modern Harleys have 90-131” engines rated at 70-121 HP, which equals to 0.8-0.9 HP/ci. In contrast, average big motorcycles have 30-80” engines rated at 65-160 HP, which translates to about 2-2.5 HP/ci.
Based on that, it’s safe to say that Harleys offer less than half the horsepower as other big motorcycles.
Are you wondering what the reasons for this are?
Keep reading!
6 Reasons Why Harleys Have Low Horsepower Figures
1. Harleys are Built for Cruising
The first and main reason why Harley-Davidsons have less horsepower than other motorcycles is that they are built for cruising rather than riding at very high speeds.
Cruiser motorcycles offer a relaxing riding position, comfortable suspensions, and a unique appearance, and Harleys are no exception.
They are great for long rides at slower speeds, allowing you to enjoy the landscape without getting tired early.
Owning a Harley-Davidson is often part of an entire lifestyle, much more so than any other brand.
2. Harley Engines Are Tuned for Torque
It’s safe to say that the engines of Harley-Davidsons are tuned for torque rather than high HP.
And the riding experience is not only about horsepower since the torque also plays a big role here!
Harley engines are known for their massive low-end torque, which ensures fun even at lower speeds. For example, the latest Milwaukee-8 engine family delivers a remarkable torque of 101-131 ft-lb.
3. V-twin Engine Configuration
Another reason for the poor HP ratings of Harley engines is their 2-cylinder, V-twin configuration.
When it comes to internal combustion engines, the more cylinders the bike has the more power it can generate. This is the why 4-cylinder motorcycle engines are much more powerful than their single and twin brothers.
4. Air Cooling
It’s also good to know that Harley-Davidsons are still powered by carbureted and air-cooled engines that produce less HP than their liquid-cooled and fuel-injected relatives.
Also, they are louder, use more fuel, and run hotter than liquid-cooled engines.
On the other hand, they have fewer parts and look cool!
5. Low RPM
The long-stroke/small bore cylinder architecture of Harley engines results in much lower peak RPMs.
If you take a closer look at a Harley cylinder, you can see that it has a much longer stroke than a typical big-bore sport motorcycle. In other words, the cylinder walls of Harley are shaped like long-drink glasses while the sport bikes’ cylinders look more like old-fashioned whiskey glasses.
On top of that, since they only feature two cylinders, Harley engines have very big heavy pistons and rods.
Since these heavy pistons have to travel a greater distance due to the long stroke, they generate a lower RMP, which converts to less HP.
As a result, Harley’s massive engine internals can tolerate lots of low-end torque in the long run, but they can’t beat the performance of high-revving big-bore engines.
6. EPA Regulations
Don’t forget that the EPA’s regulations are getting tougher and tougher, limiting the performance of Harley engines.
As an example, today’s Harleys have to be equipped with EPA-regulated airbox and exhaust system, which are very restrictive for their engines.
7. Room for Modifications
Thanks to their heavy-duty, overbuilt construction, Harley engines tolerate performance modifications very well. Many riders say that Harley engines are expressly designed with customization in mind!
This is a huge advantage for Harley owners since they like to tailor their motorcycles based on their needs.
On the other hand, it’s great for the manufacturer since it makes it possible to sell a wide range of performance parts under the brand name Screamin’ Eagle.
Besides these factory performance kits, you can choose from virtually countless aftermarket Harley performance parts from various manufacturers.
Do All Harleys Have Low Horsepower?
Contrary to popular belief, not all Harleys come with low-horsepower engines. A lesser-known Harley-Davidson engine family was the Revolution series that included five different models.
These high-performance power mills packed many advanced features including dual overhead camshafts, fuel injection, and a liquid-cooling system.
The performance of the Revolution V-Rod engines started at 115 HP and went up to a whopping 165 HP, converting to 1.65-2.2 HP/ci ratios.
Conclusion
Harley-Davidson motorcycles offer less HP than many other motorcycles, but with good reason.
These motorcycles are built for cruising, so they are tuned for torque rather than high HP figures.
Hence, they are powered by traditional V-twin engines utilizing long-stroke cylinders, carburetors, and air-cooling. These engines deliver a lot of low-end torque along with excellent durability but produce less peak power than other engine configurations.
The hidden advantage of these overbuilt engines is that they tolerate many aftermarket modifications with ease.
This ensures a lot of fun for owners and a great income for aftermarket manufacturers!
