V-Twin Motorized Bicycles - Unleash the Beast

V Twin motorized bikes - Crazy Horses

What is a V-Twin engine?

A V-Twin engine is a two-cylinder piston engine, arranged in a V configuration, that shares a common crankshaft.


V twin engines have been utilized in industrial machinery, generators, and compact vehicles, but they are most commonly recognized as a popular power-plant for motorcycles.

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Why Do V-Twins Sound So Good?

Several features combine to make V-Twins sound so good.

  1. Twin V’s have a relatively long piston stroke, resulting in a lower revving power train. 
  2. The large displacement bores require a larger diameter exhaust for efficiency. Large pipes, like an organ, reverberate the engine note.
  3. Performance engines use a high compression ratio which produces a louder “bang”
  4. The firing order of the two cylinders, most often set at 45-degrees or 90-degrees, creates a distinctive off-set rhythm that is immediately recognizable.

The combination of all four factors produces the distinctive deep bass throb.

V-Twin bicycle motor
V-Twin bicycle motor kits. 650cc monster engines

Advantages of V-Twin Engines

Power and Torque

Compared to more common inline 4’s which have four pistons arranged parallel to each other, the v twin has two relatively large pistons firing at different points in the crankshaft rotation. 

The enhanced functionality of two offset cylinders develop more torque through the rev range compared to four cylinder engines with similar piston displacement.

Slimline Profile

V twin’s have a narrow, compact architecture that perfectly matches the contours of a traditional bicycle frame.


The combination of muscle and shape makes the v twin engine ideal for motorized bicycles and tricycles. The slim profile allows clearance for pedals, while the bike benefits from the traction provided by the smooth torque delivery. V twin engines are very enjoyable to ride.


The low weight of the v twin bicycle motor bestows agility and aerodynamics on the vehicle, and the low RPM torque is well suited to carrying heavy loads.


V-Twin motor skull

The relatively long piston stroke, and high compression ratio, results in a lower revving motor. The combination results in a more fuel-efficient engine compared to other configurations.


With a v twin engine kit, a motorized bicycle rider can travel greater distances without stopping to refuel.

Sound and Feel

V-twin engines are renowned for their unique sound and sensation. The firing order of the two cylinders creates a distinctive rhythm that is immediately recognizable producing a distinctive deep bass throb that has become synonymous with Harley-Davidson motorcycles. 


The vibrations created by the engine add to the sensation of muscle, filling the rider with confidence, and machismo.

Predator 670 V-Twin bicycle engine
The electric start Predator 670 is a popular v twin bicycle engine. Shown here in a bicycle frame with gas tank and cowlings removed.

V-Twin Motorized Bicycle Engines

With their combination of braun, efficiency, slim profile, and distinctive sound and feel, a V-twin engine kit is a popular choice to construct a motorized bicycle.


V-Twin bicycle engine kits offer an affordable and iconic option for motorized bicycles. They are relatively easy to install and can effortlessly propel your ride to a top speed well of over 50 miles per hour without cycling. Note that most states allow a maximum speed limit of only 20 MPH.

Popular V-Twin Bicycle Motors

There are two very popular v-twin motors which are frequently used to motorize cycles, the Honda GX630, and the Predator 670. The numbers on both of these brands refer to their cubic capacity.


The Honda V-Twin catalog features a higher compression ratio than most engines in its class. The Honda GX630 has a compression ratio of 9.3:1 and features an overhead valve (OHV) and Hemi Head design. The architecture works together to create a highly fuel-efficient engine.


The most popular choice for v twin motorized bike is the Predator 670 engine. The Predator 670 features an 8.2:1 compression ratio and can be purchased for under $900. This is a hugely attractive proposition for budget conscious motor bike conversion projects.


Both of these 22-horsepower motors can be fitted with after-market transmission kits that can easily convert them for use in a motorized bicycle. 


It is worth noting that these large capacity motors require a valid drivers license (moped licence is not sufficient). These engines are too large to be considered a moped or a motorized scooter. The provide personalization but they do not comply with motorized bicycle laws for public road use.

Brief History of V-Twin Engines

Board track race replica with oversized engine
Large engines look cool although engines over 100cc can be complicated to fit to a bicycle frame.

Early Development

V-twin engines first emerged in the late 1800s. The original design for a stationary engine was pioneered by Gottlieb Daimler in 1889. Later, the new product was adapted to motorize vehicles, and was used in the Daimler Stahlradwagen (Daimler’s second automobile).


Double V engines fit easily into the frame of regular bicycles, and engineers soon saw their potential to motorize bicycles. 

The engines were quickly revered among motorized bike enthusiasts for their torque and distinctive sound. Manufacturers began experimenting with alternative layouts and designs as V-twin manufacturing boomed. The Fusion quickly became one of the most popular motorized bicycle configurations.


The early 1900’s focused on developing these internal combustion power-plants for racing. The Big V proved perfect for performance-oriented motorized bicycles and Board Track Racers.


V-twin engines were prominent across the motor vehicle industry during the early twentieth century. The Indian Motorcycle Company was a key pioneer in the United States, having started producing motorcycles with twin v engines in 1907.


In 1909, Harley-Davidson launched their first v twin racing internal combustion engine, drawing inspiration from the racing achievements of Indian V-Twin bikes. The cylinders of these motors were set at a 45-degree angle and produced twice the power of previous single-cylinder Harleys.


During World War II, v twin engines were widely used in military motorcycles, boats, and industrial machines. Their reliability and endurance played a crucial role in the success of numerous military operations.


The V-twin gasoline engine remains popular in the motor driven cycle community today. V-twin engines can push a bicycle to speeds of 60 miles per hour, while affordable V-Twin motorized bicycle kits are popular to recreate vintage Board Track Race replica motorized bikes.

V twin motorcycle
V-Twin bicycle engines look cool although they can be complicated to fit to a bicycle frame.

Harley-Davidson Dominance

Harley-Davidson is THE symbolic manufacturer of American V-twin engines.


Producing V-twin engines since the early 1900s, the name has become synonymous with the configuration. Harley-Davidson engines are renowned for their distinctive sound and are an icon of American motorcycle industry.

In 1907, William Harley and the Davidson brothers began developing a 45-degree V-twin engine, which had double the power at the rear wheel (compared to their single-cylinder bikes), and a maximum speed of 60 MPH.


The earliest production Harley-Davidson V-twin engine, the 45-degree F-Head, was introduced in 1911. 


In 1929, the F-Head engine was replaced by the more advanced Flathead engine.


Over the years, the Indian Motorcycle Company and Harley-Davidson brands became synonymous with the V-Twin. Both companies became iconic American motorcycle manufacturers. 


Harley-Davidson engines especially, are renowned as a cultural emblem of American motorcycle culture. 


The company has continued to innovate and improve its V-twin engines over the years, introducing several innovative designs.


Harley-Davidson continues to improve its V-twin engines. The most recent design was released in 2016. The Milwaukee-Eight, features four valves per cylinder to improve performance and efficiency.


The compact design, force, and fuel efficiency of V-twin engines make them ideal for use in motorized bicycles. The unique sound and iconic image add to the overall riding experience.

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Build the ultimate motorized bicycle with a V-Twin motorized bike engine. We investigate what makes twin V engines great
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