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A '''parallel twin''',<ref>Fundamentals of automotive engine balance. W. Thomson. Mechanical Engineering Publications, 1978 </ref><ref>The design and tuning of competition engines. Philip Hubert Smith, David N. Wenner. R. Bentley, 1977 - Technology & Engineering </ref> (aka '''straight''', '''inline''', '''transverse''' or '''vertical twin''', or '''straight-two engine''' {{fact|date=June 2012}}) is a two-cylinder [[Reciprocating engine|piston engine]] which has its cylinders arranged side by side. |
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There are three crankshaft configurations for this engine: 360°, 180°, and the new 270°: |
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There are three crankshaft configurations for this engine: 360°, 180°, <ref>American bicyclist and motorcyclist, Volume 6. Cycling Press, 1911</ref> and the new 270°: <ref>How Your Motorcycle Works: Your Guide to the Components & Systems of Modern Motorcycles. Peter Henshaw. Veloce Publishing Ltd, 15 Sep 2012</ref><ref name="feel">American Motorcyclist Dec 2001. P.18</ref> |
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* In a 360° engine, both pistons rise and fall together. The dynamic balance is identical to that of a single-cylinder engine, but with twice the number of ignition pulses. |
* In a 360° engine, both pistons rise and fall together. The dynamic balance is identical to that of a single-cylinder engine, but with twice the number of ignition pulses. |
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* In a 180° engine, one piston rises as the other falls. This gives good primary balance, albeit with a rocking couple; but results in irregular ignition pulses. |
* In a 180° engine, one piston rises as the other falls. This gives good primary balance, albeit with a rocking couple; but results in irregular ignition pulses. |
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* In a 270° engine, one piston follows a quarter of a turn behind the other. This is a compromise between the first two types, yielding results similar to a [[V-twin engine|V-twin]]. |
* In a 270° engine, one piston follows a quarter of a turn behind the other. This is a compromise between the first two types, yielding results similar to a [[V-twin engine|V-twin]]. |
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Unlike [[V-twin]]s, straight-twin engines do not use a common crank pin for both [[connecting rod]]s |
Unlike [[V-twin]]s, straight or parallel-twin engines do not use a common crank pin for both [[connecting rod]]s, each cylinder has its own crank pin. Most vintage British parallel-twin motorcycle engines,<ref>Let's Ride: Sonny Barger's Guide to Motorcycling. Sonny Barger, Darwin Holmstrom. HarperCollins, 8 Jun 2010</ref> such as Triumph, BSA, Norton and Royal Enfield, had two main bearings, the exception being AJS/Machless, which used a third, center main bearing. |
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Honda parallel-twin engines, which began appearing in the late 1950s,<ref>Honda Motorcycles: Everything You Need to Know About Every Honda Motorcycle Ever Built. Doug Mitchel. Krause Publications, 18 Oct 2005</ref><ref>Honda Motorcycles. Aaron Frank. MotorBooks International, 12 Jul 2003 </ref> had four main [[bearings]]. Subsequent engines had four or occasionally three main bearings, <ref>Pictorial History of Japanese Motorcycles. Cornelis Vandenheuvel. MBI Publishing Company, 18 Jul 1997 </ref> ball bearings being better than shell bearings for this engine configuration.<ref name="balls" /> Some engines have been built using a more obscure 76° crankshaft for the sake of performance benefits, as proposed by [[Phil Irving]].<ref>Classic Bike, April 1994</ref><ref>Phil Irving, 1962, as reprinted in Classic Motor Cycle, February 1992</ref> |
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Honda straight-twin engines, which began appearing in the late 1950s, had four main bearings. Subsequent straight-twin engines have four, or occasionally three, main bearings. |
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==Automobile use== |
==Automobile use== |
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[[File:Heckmotor NSU Prinz 4L.jpg|thumb| |
[[File:Heckmotor NSU Prinz 4L.jpg|thumb|Parallel-twin engine at the rear of a [[NSU Prinz#NSU Prinz 4|NSU Prinz 4L]]<ref>The design and tuning of competition engines. Philip Hubert Smith. R. Bentley, 1963 </ref>]] |
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In the past, |
In the past, parallel-twin engines have been used in very small cars (e.g. [[Microcars]], [[Kei cars|"light" cars]], and [[city car]]s such as the [[Fiat 500]] <ref>The complete handbook of automotive power trains. Jan P. Norbye. Tab Books, 1981</ref> and [[Fiat 126|126]], <ref>Popular Science Feb 1975</ref> NSU, <ref>The light car: a technical history of cars with engines of less than 1600 c.c. capacity. Cyril Francis Caunter, Science Museum (Great Britain). H.M.S.O., 1970 </ref><ref>NSU Prim. The Motor, Volume 165. Temple Press Limited, 1983</ref> and [[Mitsubishi Minica]]) and in farm equipment, notably by [[Deere & Company|John Deere]] <ref>The Art of the John Deere Tractor: Featuring Tractors from the Walter and Bruce Keller Collection. Lee Klancher. Voyageur Press, 13 May 2011</ref> whose large two-cylinder engines were used in their line of farm [[tractor]]s up until 1960. |
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From 1967 to 1972, Honda produced the [[Honda N360|N360]] and its successors N400 and N600 with straight-twin engines in 360 cc, 400 cc, and 600 cc sizes. The [[Honda Z600|Z600]] was produced from 1970 to 1972. From 1958 to 1971, Subaru produced the [[Subaru 360|360]] with a rear-mounted, rear-drive 358 cc air-cooled engine. |
From 1967 to 1972, Honda produced the [[Honda N360|N360]] and its successors N400 and N600 with straight-twin engines in 360 cc, 400 cc, and 600 cc sizes. The [[Honda Z600|Z600]] was produced from 1970 to 1972. From 1958 to 1971, Subaru produced the [[Subaru 360|360]] with a rear-mounted, rear-drive 358 cc air-cooled engine. |
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Current production cars that use an inline twin engine include the [[Tata Nano]], which has a 623 cc engine |
Current production cars that use an inline twin engine include the [[Tata Nano]], <ref>World's cheapest car launched: Tata Nano, Autocar, [http://www.autocar.co.uk/car-news/new-cars/worlds-cheapest-car-launched-tata-nano]</ref>which has a 623 cc engine, the [[Fiat 500 (2007)|Fiat 500]] TwinAir, which has a [[Turbocharger|turbocharged]] 875 cc engine,<ref>{{cite web |
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| url = http://green.autoblog.com/2010/07/13/fiats-twin air-2-cylinder-engine-makes-the-500-pure-fun/ |title=Fiat's TwinAir 2-cylinder engine makes the 500 pure fun |publisher=autoblog.com | |
| url = http://green.autoblog.com/2010/07/13/fiats-twin air-2-cylinder-engine-makes-the-500-pure-fun/ |title=Fiat's TwinAir 2-cylinder engine makes the 500 pure fun |publisher=autoblog.com | |
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| accessdate = 2010-08-01 |
| accessdate = 2010-08-01 |
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}}</ref> and the VW Up, which uses a parallel-twin turbodiesel. <ref>Volkswagen reveals four new Up city cars, The Telegraph, 03 Feb 2012 [http://www.telegraph.co.uk/motoring/news/9059612/Volkswagen-reveals-four-new-Up-city-cars.html]</ref> |
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}}</ref> |
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[[Ferrari]] briefly tested a two-cylinder engine for [[Formula One]] use in the 1950s, designed by [[Aurelio Lampredi]]. {{fact|date=June 2012}} |
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[[Ferrari]] briefly considered creating an inline two-cylinder engine for [[Formula One]] use in the 1950s. [[Aurelio Lampredi]] worked with [[Enzo Ferrari|Enzo]] and [[Alfredino Ferrari|Dino Ferrari]] on [[Ferrari Lampredi engine|this design]] but abandoned the development after some tests of the engine in the F1-racer of that time. They hoped that the good low-end torque would make good for the lesser maximum power on twisting street-courses, but the fast escalating maximum power of the multi-cylinder-engines and the growing number of high-speed-courses killed the project.<ref>"Schnelle Motoren" (Author = Helmut Hütten)</ref> |
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==Motorcycle use== |
==Motorcycle use== |
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[[File:YamahaTRX.jpg|thumb|upright|[[Yamaha TRX850]], a dohc 270° parallel-twin]] |
[[File:YamahaTRX.jpg|thumb|upright|[[Yamaha TRX850]], a dohc 270° parallel-twin]] |
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The motorcycle world generally refers to these engines as "parallel twins" or "vertical twins", and the term "straight-two" is obsolete. "Parallel twin" refers to an engine mounted transversely across the frame; and the term "inline twin" refers to exclusively to an engine mounted inline with the frame, such as the [[Sunbeam S7]]. In four-stroke designs, the parallel twin is usually vertical or near vertical. |
The motorcycle world generally refers to these engines as "parallel twins" <ref>American Motorcyclist, Jul 1965</ref><ref>Modern Motorcycle Technology: How Every Part of Your Motorcycle Works. Massimo Clarke. MotorBooks International, 17 Apr 2010</ref><ref>The Art of BMW: 85 Years of Motorcycling Excellence. Peter Gantriis, Henry Von Wartenberg. MotorBooks International, 15 Sep 2008</ref><ref>Pictorial History of Japanese Motorcycles. Cornelis Vandenheuvel. MBI Publishing Company, 18 Jul 1997</ref><ref>Modern Motorcycle Technology. Edward Abdo. Cengage Learning, 3 Jan 2012</ref><ref>American Motorcyclist, Dec 2004</ref><ref>The Illustrated Directory of Motorcycles. Mirco De Cet. MotorBooks International, 13 Feb 2003</ref> or "vertical twins", and the term "straight-two" is obsolete. "Parallel twin" refers to an engine which has its crankshaft mounted transversely across the frame; and the term "inline twin" refers to exclusively to an engine with its crankshaft mounted inline with the frame, such as the [[Sunbeam S7]]. <ref>The BSA Bantam Bible: All Models 1948 to 1971. Peter Henshaw. Veloce Publishing Ltd, 15 Jun 2008</ref> In four-stroke designs, the parallel twin is usually vertical or near vertical. One exception is the only parallel-twin to win a 500cc Grand Prix, the [[supercharger|supercharged]] AJS E-90 Porcupine <ref name="parallel-twin"> 365 Motorcycles You Must Ride, Dain Gingerelli, Charles Everitt, James Manning Michels. MBI Publishing Company, 10 Jan 2011</ref> which featured nearly horizontal cylinders. |
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[[Edward Turner]]'s 1937 [[Triumph Speed Twin]] started a trend, and up to the mid-1970s [[four-stroke engine|four-stroke]] parallel |
[[Edward Turner]]'s 1937 [[Triumph Speed Twin]] started a trend, <ref>Triumph: A Century of Passion and Power. Lindsay Brooke. MotorBooks International, 5 Jan 2003 </ref> and up to the mid-1970s [[four-stroke engine|four-stroke]] parallel-twins were the most common type of British motorcycles, being produced by Triumph, BSA, Norton, Ariel, Matchless and AJS. Italian, German <ref>Parallel Universe. American Motorcyclist Dec 2004. P.13</ref> and USA manufacturers have also made parallel-twins. BMW <ref>Modern Motorcycle Technology: How Every Part of Your Motorcycle Works. Massimo Clarke. MotorBooks International, 17 Apr 2010</ref> and Japanese manufacturers still make them, particularly for middleweight bikes. American made parallel-twins included the 1949 440 cc Indian Scout <ref name="parallel-twin" /> and the 1950 500 cc Indian Warrior.<ref>Walneck's Classic Cycle Trader, February 1987</ref> |
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Although the rise in popularity of the large V-twin motorcycle has seen the parallel twin fall out of favour, the latter retains these advantages over the former:<ref>''Fast Bike'' magazine August 1995 page 21</ref> |
Although the rise in popularity of the large V-twin motorcycle has seen the parallel twin fall out of favour, the latter retains these advantages over the former:<ref>''Fast Bike'' magazine August 1995 page 21</ref> |
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* Provided a 270° crank is used, a parallel twin can simulate the "feel" of a V-twin. |
* Provided a 270° crank is used, a parallel twin can simulate the "feel" of a V-twin. |
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==Other uses== |
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===Crank angle (360° and 180°)=== |
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Parallel-twins engines are commonly used by the American ATV, <ref>American Motorcyclist Feb 2003</ref> jet ski <ref>Popular Mechanics May 2003. P.116</ref> and snowmobiles <ref>Field & Stream Oct 1972. P. 10</ref> manufacturer Polaris and Japanese manufacturers, large [[Scooter_(motorcycle)|scooter]]s such as the [[Yamaha TMAX]]<ref>Motor Cycle News [http://www.motorcyclenews.com/MCN/bikereviews/searchresults/Bike-Reviews/Yamaha/Yamaha-YP500-T-Max-2001-current/ Yamaha T-Max (2001-2011)]</ref> and in motorcross sidecar racing. <ref>Off-Road Giants!: Heroes of 1960s Motorcycle Sport. Andy Westlake. Veloce Publishing Ltd, 15 Nov 2008</ref> |
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⚫ | |||
==360° and 180° Crankshaft angle== |
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⚫ | From the 1930s, following the work of [[Val Page]], most British four-stroke parallel twin motorcycles used a [[Piston motion equations#Definitions|crank angle]] of 360°, <ref>JAE: the journal of automotive engineering, Volume 2. Institution of Mechanical Engineers (Great Britain). Automobile Division. Automobile Division, Institution of Mechanical Engineers., 1971</ref> which allowed the use of a single carburettor because 180° and 270° twins need twin carburettors, as did an early [[Meguro motorcycles|Meguro]] was a copy of the 360° British [[BSA A7]]. However, in the 1960s Japanese manufacturers favoured the 180° whose smoothness allowed higher rpm and thus more power. For example, the 1966 Honda 450 cc dohc 180° parallel-twin “Black Bomber" could challenge contemporary British 650 cc 360° twins.<ref>World's Fastest Motorcycles. John Cutts, Michael Scott. Book Sales, 1 Aug 1991</ref><ref>Edward Turner: The Man Behind the Motorcycles. Jeff Clew. Veloce Publishing Ltd, 1 Feb 2007 </ref><ref>Classic superbikes from around the world. Mac McDiarmid. Parragon, 1 Jan 1995 </ref> |
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Many small motorcycles of less than 250 cc use a 360° crankshaft as the vibration issue was less significant; examples includes Honda's CB92, CB160, CA72, CA77s, and CM185. Larger twins over 500 cc, such as the Yamaha's XS650 and TX750, have used 360° crankshafts, but such parallel twins tend to feature balance shafts. The Honda CB-series in the 250 to 500 cc range used 180° crankshafts. Both the 1973 Yamaha TX500 and the 1977 Suzuki GS400 featured a 180° crankshaft and a balance shaft, while the 1974 Kawasaki KZ400 used a 360° crankshaft and a balance shaft. |
Many small motorcycles of less than 250 cc use a 360° crankshaft as the vibration issue was less significant; examples includes Honda's CB92, CB160, CA72, CA77s, and CM185. Larger twins over 500 cc, such as the Yamaha's XS650 and TX750, have used 360° crankshafts, but such parallel twins tend to feature balance shafts.<ref name="balls">Pictorial History of Japanese Motorcycles. Cornelis Vandenheuvel. MBI Publishing Company, 18 Jul 1997</ref> The Honda CB-series in the 250 to 500 cc range used 180° crankshafts. Both the 1973 Yamaha TX500 and the 1977 Suzuki GS400 featured a 180° crankshaft and a balance shaft, while the 1974 Kawasaki KZ400 used a 360° crankshaft and a balance shaft. |
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A 180° crankshaft engine suffers fewer pumping losses than a 360° twin, as displacement in the crankcase stays roughly constant. However, a 180° engine requires a separate ignition system, points or otherwise, for each cylinder. The 360° twins can have a single ignition system for both cylinders, with a [[wasted spark]] on each cylinder's exhaust stroke. The [[BMW GS parallel-twin|BMW F800]] parallel twin motorcycle is a 360° design. Inherent vibration in the BMW F800 means its engine is limited to 9,000 rpm. BMW reduced the vibration using a third "vestigial" connecting rod to act as a counterbalance. |
A 180° crankshaft engine suffers fewer pumping losses than a 360° twin, as displacement in the crankcase stays roughly constant. However, a 180° engine requires a separate ignition system, points or otherwise, for each cylinder. The 360° twins can have a single ignition system for both cylinders, with a [[wasted spark]] on each cylinder's exhaust stroke. The [[BMW GS parallel-twin|BMW F800]] parallel twin motorcycle is a 360° design. Inherent vibration in the BMW F800 means its engine is limited to 9,000 rpm. BMW reduced the vibration using a third "vestigial" connecting rod to act as a counterbalance.<ref>BMW Motorcycles. Darwin Holmstrom, Brian J. Nelson. MotorBooks International, 4 Dec 2009 </ref> |
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In [[two-stroke engine]]s, the crank angle is generally 180° with a working cycle every 180°. Such an engine will produce fewer vibrations. An exception is the [[Yankee (motorcycle)|Yankee]], which featured a 360° crankshaft. The Yankee's configuration, which featured separate combustion chambers for the two cylinders, should not be confused with that of a [[split-single]]. |
In [[two-stroke engine]]s, the crank angle is generally 180° with a working cycle every 180°. Such an engine will produce fewer vibrations. An exception is the [[Yankee (motorcycle)|Yankee]], which featured a 360° crankshaft. The Yankee's configuration, which featured separate combustion chambers for the two cylinders, should not be confused with that of a [[split-single]]. |
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== |
==270° Crankshaft angle== |
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A modern development is the 270° crank, |
A modern development of the parallel-twin engine is the 270° crank, <ref>Cycle world, Volume 46. CBS Publications, 2007</ref><ref>How Your Motorcycle Works: Your Guide to the Components & Systems of Modern Motorcycles. Peter Henshaw. Veloce Publishing Ltd, 15 Sep 2012 </ref> which imitates the sound and feel of a 90° V-twin <ref name="feel" /> but requires a balance shaft to reduce vibration. Effectively, the 270° crank is a compromise which allows a more regular firing pattern than a 180° crank and less vibration than a 360° crank. Just like a 90° V-twin, both pistons in 270° engine are never stationary thereby aiding crankshaft [[momentum]]. |
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==References== |
==References== |
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{{Reflist}} |
{{Reflist|2}} |
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==External links== |
==External links== |
Revision as of 11:11, 29 June 2012
A parallel twin,[1][2] (aka straight, inline, transverse or vertical twin, or straight-two engine [citation needed]) is a two-cylinder piston engine which has its cylinders arranged side by side.
There are three crankshaft configurations for this engine: 360°, 180°, [3] and the new 270°: [4][5]
- In a 360° engine, both pistons rise and fall together. The dynamic balance is identical to that of a single-cylinder engine, but with twice the number of ignition pulses.
- In a 180° engine, one piston rises as the other falls. This gives good primary balance, albeit with a rocking couple; but results in irregular ignition pulses.
- In a 270° engine, one piston follows a quarter of a turn behind the other. This is a compromise between the first two types, yielding results similar to a V-twin.
Unlike V-twins, straight or parallel-twin engines do not use a common crank pin for both connecting rods, each cylinder has its own crank pin. Most vintage British parallel-twin motorcycle engines,[6] such as Triumph, BSA, Norton and Royal Enfield, had two main bearings, the exception being AJS/Machless, which used a third, center main bearing.
Honda parallel-twin engines, which began appearing in the late 1950s,[7][8] had four main bearings. Subsequent engines had four or occasionally three main bearings, [9] ball bearings being better than shell bearings for this engine configuration.[10] Some engines have been built using a more obscure 76° crankshaft for the sake of performance benefits, as proposed by Phil Irving.[11][12]
Automobile use
![](https://upload.wikimedia.org/wikipedia/commons/thumb/6/61/Heckmotor_NSU_Prinz_4L.jpg/220px-Heckmotor_NSU_Prinz_4L.jpg)
In the past, parallel-twin engines have been used in very small cars (e.g. Microcars, "light" cars, and city cars such as the Fiat 500 [14] and 126, [15] NSU, [16][17] and Mitsubishi Minica) and in farm equipment, notably by John Deere [18] whose large two-cylinder engines were used in their line of farm tractors up until 1960.
From 1967 to 1972, Honda produced the N360 and its successors N400 and N600 with straight-twin engines in 360 cc, 400 cc, and 600 cc sizes. The Z600 was produced from 1970 to 1972. From 1958 to 1971, Subaru produced the 360 with a rear-mounted, rear-drive 358 cc air-cooled engine.
Current production cars that use an inline twin engine include the Tata Nano, [19]which has a 623 cc engine, the Fiat 500 TwinAir, which has a turbocharged 875 cc engine,[20] and the VW Up, which uses a parallel-twin turbodiesel. [21]
Ferrari briefly tested a two-cylinder engine for Formula One use in the 1950s, designed by Aurelio Lampredi. [citation needed]
Motorcycle use
![](https://upload.wikimedia.org/wikipedia/commons/thumb/1/11/W800_K%C3%B6nigswelle.jpg/170px-W800_K%C3%B6nigswelle.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/e/ee/NortonCommandoMKIIA.jpg/220px-NortonCommandoMKIIA.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/d/d4/1974_Honda_CB450_K7.jpg/220px-1974_Honda_CB450_K7.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/d/db/YamahaTRX.jpg/170px-YamahaTRX.jpg)
The motorcycle world generally refers to these engines as "parallel twins" [22][23][24][25][26][27][28] or "vertical twins", and the term "straight-two" is obsolete. "Parallel twin" refers to an engine which has its crankshaft mounted transversely across the frame; and the term "inline twin" refers to exclusively to an engine with its crankshaft mounted inline with the frame, such as the Sunbeam S7. [29] In four-stroke designs, the parallel twin is usually vertical or near vertical. One exception is the only parallel-twin to win a 500cc Grand Prix, the supercharged AJS E-90 Porcupine [30] which featured nearly horizontal cylinders.
Edward Turner's 1937 Triumph Speed Twin started a trend, [31] and up to the mid-1970s four-stroke parallel-twins were the most common type of British motorcycles, being produced by Triumph, BSA, Norton, Ariel, Matchless and AJS. Italian, German [32] and USA manufacturers have also made parallel-twins. BMW [33] and Japanese manufacturers still make them, particularly for middleweight bikes. American made parallel-twins included the 1949 440 cc Indian Scout [30] and the 1950 500 cc Indian Warrior.[34]
Although the rise in popularity of the large V-twin motorcycle has seen the parallel twin fall out of favour, the latter retains these advantages over the former:[35]
- A parallel twin is cheaper to make, having only one cylinder block and one cylinder head.
- Both cylinders can have the exhaust pipe exiting at the front, in the cool air stream.
- Siting of ancillaries (air-filter, carburetters, ignition etc.) is simpler.
- This simpler layout can potentially make maintenance access easier.
- The parallel twin is both lighter and shorter, allowing a lighter frame and shorter wheelbase.
- The motorcycle's centre of gravity can be sited optimally, i.e. lower and further forward.
- Provided a 270° crank is used, a parallel twin can simulate the "feel" of a V-twin.
Other uses
Parallel-twins engines are commonly used by the American ATV, [36] jet ski [37] and snowmobiles [38] manufacturer Polaris and Japanese manufacturers, large scooters such as the Yamaha TMAX[39] and in motorcross sidecar racing. [40]
360° and 180° Crankshaft angle
From the 1930s, following the work of Val Page, most British four-stroke parallel twin motorcycles used a crank angle of 360°, [41] which allowed the use of a single carburettor because 180° and 270° twins need twin carburettors, as did an early Meguro was a copy of the 360° British BSA A7. However, in the 1960s Japanese manufacturers favoured the 180° whose smoothness allowed higher rpm and thus more power. For example, the 1966 Honda 450 cc dohc 180° parallel-twin “Black Bomber" could challenge contemporary British 650 cc 360° twins.[42][43][44]
Many small motorcycles of less than 250 cc use a 360° crankshaft as the vibration issue was less significant; examples includes Honda's CB92, CB160, CA72, CA77s, and CM185. Larger twins over 500 cc, such as the Yamaha's XS650 and TX750, have used 360° crankshafts, but such parallel twins tend to feature balance shafts.[10] The Honda CB-series in the 250 to 500 cc range used 180° crankshafts. Both the 1973 Yamaha TX500 and the 1977 Suzuki GS400 featured a 180° crankshaft and a balance shaft, while the 1974 Kawasaki KZ400 used a 360° crankshaft and a balance shaft.
A 180° crankshaft engine suffers fewer pumping losses than a 360° twin, as displacement in the crankcase stays roughly constant. However, a 180° engine requires a separate ignition system, points or otherwise, for each cylinder. The 360° twins can have a single ignition system for both cylinders, with a wasted spark on each cylinder's exhaust stroke. The BMW F800 parallel twin motorcycle is a 360° design. Inherent vibration in the BMW F800 means its engine is limited to 9,000 rpm. BMW reduced the vibration using a third "vestigial" connecting rod to act as a counterbalance.[45]
In two-stroke engines, the crank angle is generally 180° with a working cycle every 180°. Such an engine will produce fewer vibrations. An exception is the Yankee, which featured a 360° crankshaft. The Yankee's configuration, which featured separate combustion chambers for the two cylinders, should not be confused with that of a split-single.
270° Crankshaft angle
A modern development of the parallel-twin engine is the 270° crank, [46][47] which imitates the sound and feel of a 90° V-twin [5] but requires a balance shaft to reduce vibration. Effectively, the 270° crank is a compromise which allows a more regular firing pattern than a 180° crank and less vibration than a 360° crank. Just like a 90° V-twin, both pistons in 270° engine are never stationary thereby aiding crankshaft momentum.
References
- ^ Fundamentals of automotive engine balance. W. Thomson. Mechanical Engineering Publications, 1978
- ^ The design and tuning of competition engines. Philip Hubert Smith, David N. Wenner. R. Bentley, 1977 - Technology & Engineering
- ^ American bicyclist and motorcyclist, Volume 6. Cycling Press, 1911
- ^ How Your Motorcycle Works: Your Guide to the Components & Systems of Modern Motorcycles. Peter Henshaw. Veloce Publishing Ltd, 15 Sep 2012
- ^ a b American Motorcyclist Dec 2001. P.18
- ^ Let's Ride: Sonny Barger's Guide to Motorcycling. Sonny Barger, Darwin Holmstrom. HarperCollins, 8 Jun 2010
- ^ Honda Motorcycles: Everything You Need to Know About Every Honda Motorcycle Ever Built. Doug Mitchel. Krause Publications, 18 Oct 2005
- ^ Honda Motorcycles. Aaron Frank. MotorBooks International, 12 Jul 2003
- ^ Pictorial History of Japanese Motorcycles. Cornelis Vandenheuvel. MBI Publishing Company, 18 Jul 1997
- ^ a b Pictorial History of Japanese Motorcycles. Cornelis Vandenheuvel. MBI Publishing Company, 18 Jul 1997
- ^ Classic Bike, April 1994
- ^ Phil Irving, 1962, as reprinted in Classic Motor Cycle, February 1992
- ^ The design and tuning of competition engines. Philip Hubert Smith. R. Bentley, 1963
- ^ The complete handbook of automotive power trains. Jan P. Norbye. Tab Books, 1981
- ^ Popular Science Feb 1975
- ^ The light car: a technical history of cars with engines of less than 1600 c.c. capacity. Cyril Francis Caunter, Science Museum (Great Britain). H.M.S.O., 1970
- ^ NSU Prim. The Motor, Volume 165. Temple Press Limited, 1983
- ^ The Art of the John Deere Tractor: Featuring Tractors from the Walter and Bruce Keller Collection. Lee Klancher. Voyageur Press, 13 May 2011
- ^ World's cheapest car launched: Tata Nano, Autocar, [1]
- ^ air-2-cylinder-engine-makes-the-500-pure-fun/ "Fiat's TwinAir 2-cylinder engine makes the 500 pure fun". autoblog.com. Retrieved 2010-08-01.
{{cite web}}
: Check|url=
value (help); Cite has empty unknown parameter:|1=
(help) - ^ Volkswagen reveals four new Up city cars, The Telegraph, 03 Feb 2012 [2]
- ^ American Motorcyclist, Jul 1965
- ^ Modern Motorcycle Technology: How Every Part of Your Motorcycle Works. Massimo Clarke. MotorBooks International, 17 Apr 2010
- ^ The Art of BMW: 85 Years of Motorcycling Excellence. Peter Gantriis, Henry Von Wartenberg. MotorBooks International, 15 Sep 2008
- ^ Pictorial History of Japanese Motorcycles. Cornelis Vandenheuvel. MBI Publishing Company, 18 Jul 1997
- ^ Modern Motorcycle Technology. Edward Abdo. Cengage Learning, 3 Jan 2012
- ^ American Motorcyclist, Dec 2004
- ^ The Illustrated Directory of Motorcycles. Mirco De Cet. MotorBooks International, 13 Feb 2003
- ^ The BSA Bantam Bible: All Models 1948 to 1971. Peter Henshaw. Veloce Publishing Ltd, 15 Jun 2008
- ^ a b 365 Motorcycles You Must Ride, Dain Gingerelli, Charles Everitt, James Manning Michels. MBI Publishing Company, 10 Jan 2011
- ^ Triumph: A Century of Passion and Power. Lindsay Brooke. MotorBooks International, 5 Jan 2003
- ^ Parallel Universe. American Motorcyclist Dec 2004. P.13
- ^ Modern Motorcycle Technology: How Every Part of Your Motorcycle Works. Massimo Clarke. MotorBooks International, 17 Apr 2010
- ^ Walneck's Classic Cycle Trader, February 1987
- ^ Fast Bike magazine August 1995 page 21
- ^ American Motorcyclist Feb 2003
- ^ Popular Mechanics May 2003. P.116
- ^ Field & Stream Oct 1972. P. 10
- ^ Motor Cycle News Yamaha T-Max (2001-2011)
- ^ Off-Road Giants!: Heroes of 1960s Motorcycle Sport. Andy Westlake. Veloce Publishing Ltd, 15 Nov 2008
- ^ JAE: the journal of automotive engineering, Volume 2. Institution of Mechanical Engineers (Great Britain). Automobile Division. Automobile Division, Institution of Mechanical Engineers., 1971
- ^ World's Fastest Motorcycles. John Cutts, Michael Scott. Book Sales, 1 Aug 1991
- ^ Edward Turner: The Man Behind the Motorcycles. Jeff Clew. Veloce Publishing Ltd, 1 Feb 2007
- ^ Classic superbikes from around the world. Mac McDiarmid. Parragon, 1 Jan 1995
- ^ BMW Motorcycles. Darwin Holmstrom, Brian J. Nelson. MotorBooks International, 4 Dec 2009
- ^ Cycle world, Volume 46. CBS Publications, 2007
- ^ How Your Motorcycle Works: Your Guide to the Components & Systems of Modern Motorcycles. Peter Henshaw. Veloce Publishing Ltd, 15 Sep 2012
External links
- A detailed analysis of the effect of different crankshaft offset angles on the engine balance of a straight twin engine.