A single-cylinder engine, sometimes called a thumper, is a

piston engine A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common feat ...

with one

cylinder A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an ...

. This engine is often used for motorcycles, motor scooters, go-karts, all-terrain vehicles, radio-controlled vehicles, portable tools and garden machinery (such as lawnmowers, cultivators, and string trimmers). Single-cylinder engines are made both as

4-stroke A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directio ...

s and

2-stroke A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being completed in one revolution of t ...

Characteristics

Compared with multi-cylinder engines, single-cylinder engines are usually simpler and compact. Due to the greater potential for airflow around all sides of the cylinder,

air cooling Air cooling is a method of dissipating heat. It works by expanding the surface area or increasing the flow of air over the object to be cooled, or both. An example of the former is to add cooling fins to the surface of the object, either by maki ...

is often more effective for single cylinder engines than multi-cylinder engines. This reduces the weight and complexity of air-cooled single-cylinder engines, compared with liquid-cooled engines. Drawbacks of single-cylinder engines include a more pulsating power delivery through each cycle and higher levels of vibration. The uneven power delivery means that often a single-cylinder engine requires a heavier

flywheel A flywheel is a mechanical device which uses the conservation of angular momentum to store rotational energy; a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, as ...

than a comparable multi-cylinder engine, resulting in relatively slower changes in engine speed. To reduce the vibration level, they often make greater use of

balance shaft Balance shafts are used in piston engines to reduce vibration by cancelling out unbalanced dynamic forces. The counter balance shafts have eccentric weights and rotate in opposite direction to each other, which generates a net vertical force. T ...

s than multi-cylinder engines, as well as more extreme methods such as a dummy connecting rod (for example the

Ducati Supermono The Ducati Supermono is a lightweight, single-cylinder racing motorcycle made by Ducati and named after the Supermono racing class. 65 Supermonos were built by Ducati between 1993 and 1995. Technology This lightweight, compact racer was built wi ...

). These balancing devices can reduce the benefits of single-cylinder engines regarding lower weight and complexity. Most single-cylinder engines used in motor vehicles are fueled by

petrol Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic c ...

(and use a

four-stroke cycle A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directi ...

), however

diesel Diesel may refer to: * Diesel engine, an internal combustion engine where ignition is caused by compression * Diesel fuel, a liquid fuel used in diesel engines * Diesel locomotive, a railway locomotive in which the prime mover is a diesel engi ...

single-cylinder engines are also used in stationary applications (such as the Lombardini 3LD and 15LD). A variation known as the split-single makes use of two pistons which share a single combustion chamber.

Uses

Detail view of a large single-cylinder air-cooled motorcycle engine

Early

motorcycle A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle Steering, steered by a Motorcycle handlebar, handlebar. Motorcycle design varies greatly to suit a range of different purposes: Long-distance ...

automobile A car or automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods. The year 1886 is regarded ...

s and other applications such as marine engines all tended to be single-cylinder. The configuration is almost exclusively used in portable tools, along with garden machinery such as lawn mowers. Single cylinder engines also remain in widespread use in motorcycles,

motor scooter A scooter (motor scooter) is a motorcycle with an underbone or step-through frame, a seat, and a platform for the rider's feet, emphasizing comfort and fuel economy. Elements of scooter design were present in some of the earliest motorcycle ...

go-kart A go-kart, also written as go-cart (often referred to as simply a kart), is a type of sports car, close wheeled car, open-wheel car or quadracycle. Go-karts come in all shapes and forms, from non-motorised models to high-performance racing ...

auto rickshaw An auto rickshaw is a motorized version of the pulled rickshaw or cycle rickshaw. Most have three wheels and do not tilt. They are known by many terms in various countries including auto, auto rickshaw, baby taxi, mototaxi, pigeon, jonnybee, bajaj ...

s, and

radio-controlled model A radio-controlled model (or RC model) is a model that is steerable with the use of radio control. All types of model vehicles have had RC systems installed in them, including ground vehicles, boats, planes, helicopters and even submarines and ...

s. From 1921-1960, the Lanz Bulldog tractor used a large horizontally-mounted single cylinder two-stroke engine. However they are rarely used in modern automobiles and tractors, due to developments in engine technology. Single cylinder engines remain the most common engine layout in

s and low-powered

s. The Honda Super Cub (the motor vehicle with the highest overall sales since its introduction in 1958) uses a four-stroke single-cylinder engine. There are also several single-cylinder

sportbike A sport bike (sports motorcycle, or sports bike) is a motorcycle designed and optimized for speed, acceleration, braking, and cornering on asphalt concrete race tracks and roads. They are mainly designed for performance at the expense of comfo ...

s (such as the KTM 690 Duke R), dual-sport motorcycles (such as the BMW G650GS) and the classic-styled Royal Enfield 500 Bullet. The Moto3 class in the MotoGP World Championship have used four-stroke 250cc (15.2 cu in) single cylinder engines since the class replaced 125cc two-strokes in

2012 File:2012 Events Collage V3.png, From left, clockwise: The passenger cruise ship Costa Concordia lies capsized after the Costa Concordia disaster; Damage to Casino Pier in Seaside Heights, New Jersey as a result of Hurricane Sandy; People gat ...

References

{{Authority control Motorcycle engines Engines by cylinder layout

Characteristics

Uses

See also

References