A single-cylinder engine, sometimes called a thumper, is a piston engine with one cylinder. This engine is often used for

motorcycle A motorcycle (motorbike, bike; uni (if one-wheeled); trike (if three-wheeled); quad (if four-wheeled)) is a lightweight private 1-to-2 passenger personal motor vehicle Steering, steered by a Motorcycle handlebar, handlebar from a saddle-style ...

s, motor scooters, motorized bicycles, go-karts,

all-terrain vehicle An all-terrain vehicle (ATV), also known as a light utility vehicle (LUV), a quad bike or quad (if it has four wheels), as defined by the American National Standards Institute (ANSI), is a vehicle that travels on low-pressure tires, has a seat ...

s, radio-controlled vehicles,

power tool A power tool is a tool that is actuator, actuated by an additional engine, power source and mechanism (engineering), mechanism other than the solely manual labour, manual labor used with hand tools. The most common types of power tools use electric ...

s and garden machinery (such as chainsaws,

lawn mower A lawn mower (also known as a grass cutter or simply mower, also often spelled lawnmower) is a device utilizing one or more revolving blades (or a reel) to cut a lawn, grass surface to an even height. The height of the cut grass may be fixed by ...

s, cultivators, and string trimmers). Single-cylinder engines are made both as 4-strokes 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 of the piston, one up and one down, in one revolution of the crankshaft in contrast to a four-stroke engine which ...

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 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 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 shafts than multi-cylinder engines, as well as more extreme methods such as a dummy connecting rod (for example the Ducati Supermono). 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 (North American English) or petrol ( Commonwealth English) is a petrochemical product characterized as a transparent, yellowish, and flammable liquid normally used as a fuel for spark-ignited internal combustion engines. When formul ...

(and use a four-stroke cycle), however diesel 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

automobile A car, or an automobile, is a motor vehicle with wheels. Most definitions of cars state that they run primarily on roads, Car seat, seat one to eight people, have four wheels, and mainly transport private transport#Personal transport, peopl ...

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 scooters, go-karts,

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 other terms in various countries, including three-wheeler, Adaidaita Sahu, Keke-napep, Maruwa, auto, ...

s, and radio-controlled models. From 1921 to 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 motor scooters 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 sports motorcycle, sports bike, or sport 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 single cylinder engines since the class replaced two-strokes in

2012 2012 was designated as: *International Year of Cooperatives *International Year of Sustainable Energy for All Events January *January 4 – The Cicada 3301 internet hunt begins. * January 12 – Peaceful protests begin in the R ...

Other single-cylinder engines

Engines of other sorts, like the beam engine and certain types of

Stirling engine A Stirling engine is a heat engine that is operated by the cyclic expansion and contraction of air or other gas (the ''working fluid'') by exposing it to different temperatures, resulting in a net conversion of heat energy to mechanical Work (ph ...

, operate using one cylinder and thus can also be considered single-cylinder engines.

References

{{Authority control Motorcycle engines Engines by cylinder layout