Single-cylinder engine

Last updated
DKW RT 250 (1952-1953) motorcycle engine 2007-05-20 3 DKW RT 250 in Mendig (kl).JPG
DKW RT 250 (1952–1953) motorcycle engine

A single-cylinder engine, sometimes called a thumper, is a piston engine with one cylinder. 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-strokes and 2-strokes.



Villiers engine in a 1959 Bond Minicar Bond minicar engine bay 1959.jpg
Villiers engine in a 1959 Bond Minicar

Compared with multi-cylinder engines, single-cylinder engines are usually simpler and compact. [1] 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. [2] 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, [3] as well as more extreme methods such as a dummy connecting rod (for example the Ducati Supermono). [4] [5] 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 (and use a four-stroke cycle), [6] [7] [8] 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.


Yamaha SRX600 (1985-1997) motorcycle engine Detail view of a large single-cylinder air-cooled motorcycle engine.jpg
Yamaha SRX600 (1985–1997) motorcycle engine

Early motorcycles, automobiles 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. [9] Single cylinder engines also remain in widespread use in motorcycles, motor scooters, go-karts, auto rickshaws, and radio-controlled models. From 1921-1960, the Lanz Bulldog tractor used a large horizontally-mounted single cylinder two-stroke engine. [10] 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 motorcycles. The Honda Super Cub (the motor vehicle with the highest overall sales since its introduction in 1958) uses a 49 cc (3.0 cu in) four-stroke single-cylinder engine. There are also several single-cylinder sportbikes (such as the KTM 690 Duke R), dual-sport motorcycles (such as the BMW G650GS) and the classic-styled Royal Enfield 500 Bullet. [11] [12]

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.

See also

Related Research Articles

Reciprocating engine Engine utilising one or more reciprocating pistons

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 features of all types. The main types are: the internal combustion engine, used extensively in motor vehicles; the steam engine, the mainstay of the Industrial Revolution; and the Stirling engine for niche applications. Internal combustion engines are further classified in two ways: either a spark-ignition (SI) engine, where the spark plug initiates the combustion; or a compression-ignition (CI) engine, where the air within the cylinder is compressed, thus heating it, so that the heated air ignites fuel that is injected then or earlier.

V4 engine Piston engine with four cylinders in "V" configuration

A V4 engine is a four-cylinder piston engine where the cylinders share a common crankshaft and are arranged in a V configuration.

Flat-twin engine Piston engine with two cylinders in opposing directions

A flat-twin engine is a two-cylinder internal combustion engine with the cylinders on opposite sides of the crankshaft. The most common type of flat-twin engine is the boxer-twin engine, where both cylinders move inwards and outwards at the same time.

Flat-four engine Horizontally opposed four-cylinder piston engine

A flat-four engine, also known as a horizontally opposed-four engine, is a four-cylinder piston engine with two banks of cylinders lying on opposite sides of a common crankshaft. The most common type of flat-four engine is the boxer-four engine, each pair of opposed pistons moves inwards and outwards at the same time.

Straight-twin engine Inline piston engine with two cylinders

A straight-twin engine, also known as an inline-twin, vertical-twin, or parallel-twin, is a two-cylinder piston engine whose cylinders are arranged in a line along a common crankshaft.

Straight-four engine Inline piston engine with four cylinders

A straight-four engine is a four-cylinder piston engine where cylinders are arranged in a line along a common crankshaft.

<span class="mw-page-title-main">Straight-six engine</span> Internal combustion engine

The straight-six engine is an internal combustion engine, with six cylinders mounted in a straight line along the crankcase with all the pistons driving a common crankshaft.

Straight-three engine Type of engine

A straight-three engine is a three-cylinder piston engine where cylinders are arranged in a line along a common crankshaft.

Yamaha Motor Co., Ltd. is a Japanese multinational manufacturer of motorcycles, marine products such as boats and outboard motors, and other motorized products. The company was established in 1955 upon separation from Yamaha Corporation, and is headquartered in Iwata, Shizuoka, Japan. The company conducts development, production and marketing operations through 109 consolidated subsidiaries as of 2012.

Balance shaft Weights used to balance otherwise unbalanced engine movement

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.

<span class="mw-page-title-main">Maico</span> Former car manufacturer

Maicowerk A.G., known by its trading name Maico is the name of a family company in the Swabian town of Pfäffingen near Tübingen. Founded in 1926 by Ulrich Maisch as Maisch & Co, the company originally manufactured 98 and 123 cc Ilo two-stroke engines. After World War II, they began producing their own unit construction two-stroke engines, selling complete motorcycles. Maico made a brief foray into the automobile business with their own line of microcars in the late 1950s. Maico have also made go kart engines.

Phelon & Moore

Phelon & Moore manufactured motorcycles in Cleckheaton, Yorkshire, England from 1904 to 1967 particularly those under the Panther marque. They became identified with one particular design of motorcycle which had a large sloping 40-degree single-cylinder engine as a stressed member of the frame. This design spanned the entire history of the company, starting with a 500 cc model and ending with a 645 cc model.

Motorcycle engine Engine that powers a motorcycle

A motorcycle engine is an engine that powers a motorcycle. Motorcycle engines are typically two-stroke or four-stroke internal combustion engines, but other engine types, such as Wankels and electric motors, have been used.

Types of motorcycles Types of motorcycles

The six main types of motorcycles are generally recognized as standard, cruiser, touring, sports, off-road, and dual-purpose. Sport touring is sometimes recognized as a seventh category or integrated with the touring category.

Suzuki Boulevard S40 Type of motorcycle

The Suzuki Boulevard S40 is a lightweight cruiser motorcycle manufactured by the Suzuki Motor Corporation for the Japanese domestic market, and exported to New Zealand, North America, as well as to Chile and other countries.

Villiers Engineering Historical motorcycle manufacturer

Villiers Engineering was a manufacturer of motorcycles and cycle parts, and an engineering company based in Villiers Street, Wolverhampton, England.

Motorcycle components and systems for a motorcycle are engineered, manufactured, and assembled in order to produce motorcycle models with the desired performance, aesthetics, and cost. The key components of modern motorcycles are presented below.

Split-single engine Type of two-stroke internal combustion engine

In internal combustion engines, a split-single design is a type of two-stroke where two cylinders share a single combustion chamber.

A big bang engine is an unconventional engine designed so that some of the power strokes occur simultaneously or in close succession. This is achieved by changing the ignition timing, changing or re-timing the camshaft, and sometimes in combination with a change in crankpin angle. The goal is to change the power delivery characteristics of the engine. A regular firing multi-cylinder engine fires at approximately even intervals, giving a smooth-running engine. Because a big-bang engine has uneven power delivery, they tend to run rougher and generate more vibration than an even-firing engine.

MV Agusta 125 Pullman Type of motorcycle

The MV Agusta 125 Pullman was a motorcycle produced by the Italian manufacturer MV Agusta from 1953 to 1956. The model achieved a good sales success, and had the highest production of any machine from MV Agusta. Many brought the bike as the only means of family transport or as a work vehicle. Despite the questionable aesthetics, the Pullman offered a comfortable ride, derived by the driving position, soft suspension and large section tires. This was particularly appreciated by users, so much so that they were imitated by some competitors. 27,000 machines of this model series were produced. The model was also produced under licence in Spain by Avello, where it was marketed as the MV Avello 125 Pullman Turismo.


  1. "Single Cylinder Engines". TheBikeMarket. Archived from the original on 2019-12-17.
  2. "How to Balancing a Single Cylinder Engine Crankshaft and Piston/Connecting Rod Assembly and Flywheel to Reduce Dangerous Vibration". Retrieved 10 July 2019.
  3. "Engine Science: The Balancing Act of Single Cylinder Engines". Retrieved 10 July 2019.
  4. Methods of Balancing Single Cylinder Engines. Joseph R. Harkness. SAE Transactions. Vol. 77, Section 3: Papers 680436–680591 (1968), pp. 2329-2338
  5. Suzuki's Supermono Engine Design. A second con-rod without a piston. Ben Purvis. April 26, 2019
  6. "5 of the funkiest single-cylinder street bikes". 5 March 2009. Retrieved 7 July 2019.
  7. "The Single Life: 6 of the best thumpers". Retrieved 7 July 2019.
  8. "The 16 Best Retro Motorcycles Make Bikes Great, Again". 9 August 2016. Retrieved 7 July 2019.
  9. "How Car Engines Work". 5 April 2000. Retrieved 10 July 2019.
  10. "The Lanz Bulldog". Retrieved 10 July 2019.
  11. "690 Duke: The essence of motorcycling". Archived from the original on 2012-06-12. Retrieved 2012-06-01.
  12. David Blasco. "Royal Enfield Motorcycles". Archived from the original on 2011-12-07. Retrieved 2011-12-06.