Single-cylinder engine
{{Short description|Piston engine with one cylinder}}
File:2007-05-20 3 DKW RT 250 in Mendig (kl).JPG 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, motorized bicycles, go-karts, all-terrain vehicles, radio-controlled vehicles, power tools and garden machinery (such as chainsaws, lawn mowers, cultivators, and string trimmers). Single-cylinder engines are made both as 4-strokes and 2-strokes.
Characteristics
File:Bond minicar engine bay 1959.jpg engine in a 1959 Bond Minicar ]]
Compared with multi-cylinder engines, single-cylinder engines are usually simpler and compact.{{cite web |title=Single Cylinder Engines |url=https://www.thebikemarket.co.uk/advice/single-cylinder-engines | website = TheBikeMarket | archiveurl = https://web.archive.org/web/20191217103057/https://www.thebikemarket.co.uk/advice/single-cylinder-engines | archivedate = 2019-12-17 }} 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.{{cite web |title=How to Balancing a Single Cylinder Engine Crankshaft and Piston/Connecting Rod Assembly and Flywheel to Reduce Dangerous Vibration |url=http://gardentractorpullingtips.com/balance.htm |website=www.gardentractorpullingtips.com |access-date=10 July 2019}} 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,{{cite web |title=Engine Science: The Balancing Act of Single Cylinder Engines |url=https://isavetractors.com/articles-1/engine-science-the-balancing-act-of-single-cylinder-engines/ |website=www.isavetractors.com |access-date=10 July 2019 |language=en}} as well as more extreme methods such as a dummy connecting rod (for example the Ducati Supermono).Methods of Balancing Single Cylinder Engines. Joseph R. Harkness. SAE Transactions. Vol. 77, Section 3: Papers 680436–680591 (1968), pp. 2329-2338[https://www.cycleworld.com/suzukis-supermono-engine-design Suzuki's Supermono Engine Design]. A second con-rod without a piston. Ben Purvis. April 26, 2019 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),{{cite web |title=5 of the funkiest single-cylinder street bikes |url=https://www.motorcyclenews.com/news/first-rides-tests/2009/march/mar0609-5-of-the-best-funky-singles/ |website=www.motorcyclenews.com |access-date=7 July 2019 |language=en |date=5 March 2009}}{{cite web |title=The Single Life: 6 of the best thumpers |url=https://www.bennetts.co.uk/bikesocial/news-and-views/advice/biking-tips/the-single-life-6-of-the-best/ |website=www.bennetts.co.uk |access-date=7 July 2019 |language=en}}{{cite web |title=The 16 Best Retro Motorcycles Make Bikes Great, Again |url=https://www.thecoolist.com/best-retro-motorcycles/ |website=www.thecoolist.com |access-date=7 July 2019 |date=9 August 2016}} 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
File:Detail view of a large single-cylinder air-cooled motorcycle engine.jpg (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.{{cite web |title=How Car Engines Work |url=https://auto.howstuffworks.com/engine2.htm |website=www.howstuffworks.com |access-date=10 July 2019 |language=en |date=5 April 2000}} Single cylinder engines also remain in widespread use in motorcycles, motor scooters, go-karts, auto rickshaws, and radio-controlled models. From 1921 to 1960, the Lanz Bulldog tractor used a large horizontally-mounted single cylinder two-stroke engine.{{cite web |title=The Lanz Bulldog |url=https://www.gasenginemagazine.com/tractors/the-lanz-bulldog |website=www.gasenginemagazine.com |date=December 1988 |access-date=10 July 2019 |language=en}} 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 {{convert|49|cc|cuin|1|abbr=on}} 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.{{cite web |url=http://www.ktm.com/gb/naked-bike/690-duke-ausuk.html |title=690 Duke: The essence of motorcycling |access-date=2012-06-01 |url-status=dead |archive-url=https://web.archive.org/web/20120612135532/http://www.ktm.com/gb/naked-bike/690-duke-ausuk.html |archive-date=2012-06-12 }}{{cite web |author=David Blasco |url=http://www.royalenfields.com/ |title=Royal Enfield Motorcycles |publisher=Royalenfields.com |access-date=2011-12-06 |url-status=live |archive-url=https://web.archive.org/web/20111207025443/http://www.royalenfields.com/ |archive-date=2011-12-07 }}
The Moto3 class in the MotoGP World Championship have used four-stroke {{convert|250|cc|cuin|1|abbr=on}} single cylinder engines since the class replaced {{convert|125|cc|cuin|1|abbr=on}} two-strokes in 2012.
Other single-cylinder engines
Engines of other sorts, like the beam engine and certain types of Stirling engine, operate using one cylinder and thus can also be considered single-cylinder engines.
References
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{{Piston engine configurations|state=expanded}}
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