Editing V-twin



{| align="right"
|-
|[[Image:Harley Davidson.jpg|thumb|[[Harley-Davidson]] [[Harley-Davidson FL#Unfaired Glides - Electra Glide Sport and Road King|Road King]] 45° transversely mounted V-twin.]]
|-
|[[Image:Moto Guzzi V-twin.JPG|right|thumb|[[Moto Guzzi]] Jackal with a longitudinally mounted 90° V-twin.]]
|-
|[[Image:Honda v-twin.jpg|right|thumb|[[List of Honda motorcycles|Honda]] 90° transversely mounted V-twin.]]
|-
|[[Image:DSC09063.sized.jpg|right|thumb|[[Ducati]] 90-degree transversely mounted V-twin.]]
|-
|[[Image:Honda Longitudinal V-twin.JPG|right|thumb|[[Honda GL500|Honda GL500 Silver Wing]] with a longitudinally mounted V-
twin.]]
|-
|[[Image:Sokol 995 cc zijklep v-twin.jpg|right|thumb|[[Sokół motorcycles|Sokół]] transversely mounted V-twin.]]
|}
A '''V-twin engine''', often just '''V-twin''', is a two cylinder [[internal combustion engine]] where the cylinders are arranged in a [[V engine|V]] configuration.

== Configurations ==
=== "True V-twin" vs V-2 ===

There is some ambiguity regarding what defines a V-twin. When the cylinders are arranged in a "V"-shaped pattern, it is generally accepted as being a [[V engine]]. However, some authors differentiate using "V-twin" to mean the classic V design of a shared [[crank pin]] for each pair of cylinders and "V-2" to indicate a crankshaft with a separate crank pin for each cylinder. This convention is not common, and applies only to two cylinder engines. For example, while most V8 engines use shared crank pins for cylinder pairs, they are not referred to as "V-octuplets". 

Most engine manufacturers use the classic shared crank pin design. Some notable exceptions include the
[[Moto Guzzi]] 500cc with 120° V angle and 180° crank pin offset that Stanley Woods rode to win the 1935 [[Isle of Man Tourist Trophy]];<ref> {{cite web
| url = http://www.motorcycle.com/events/i-coulda-had-a-v8-so-i-did-12730.html
| title = I Coulda Had a V-8.... so I Did
| accessdate = 2010-04-18
| quote = By 1934 Guzzi offered a range of 175, 250 and 500cc models including full touring machines. The next year they raised the ante once again, challenging the all-vanquishing Norton at the legendary Isle of Man TT, basically a course the British racer owned lock, stock and single barrel thanks to a phenomenal rider, Scotsman Jim Guthrie. Moto Guzzi went to a Brit for riding skills, one Stanley Woods. They gave him a new racer featuring a 120-degree V-twin with offset cranks firing at 180 degrees with bevel gears and shafts driving the SOHC, good enough for 44 hp at 7500 rpm and 112 mph, on equal standing with the Norton. It had an ace up its sleeve so to speak in that it incorporated a type of pivoted-fork rear suspension while the frontend was a springer, a design that had never won a Senior TT due to its handling deficiencies, or so was thought. Guzzi had done some tweaking in that department as well. It also came equipped with a massive twin-leading shoe front brake, a 4-speed gearbox, and alloy wheels, another innovation to cut down unsprung weight. When the dust had settled and the calculations determined, the wreath of victory went to Woods and Moto Guzzi, leaving Norton as they say, gobsmacked. Not only that, the Guzzi had smashed the track lap record. The next day Moto Guzzi was world famous.}}</ref>
the 1983 [[Honda Shadow]] 750, claimed as being the first V-twin with an offset-dual-pin crankshaft;<ref> {{cite web
| url = http://powersports.honda.com/the_story/heritage/heritage_milestone.asp?Decade=1980&TargetUrl=Milestone/Milestone_Model_0102.asp&PrevPageTitle=TimeLine
| title = Honda: 1983 Shadow 750
| accessdate = 2008-05-20}}</ref> and the
1987 [[Suzuki VX 800]], 45° V angle with 45° crank pin offset in USA and 75° crank pin offset for the rest of the world.<ref>{{Citation 
|title = Suzuki VX800
|journal = Cycle World
|year = 1990
|month = July
|pages = 36-37
|quote = At some point in the motorcycle's development, the company changed the crankpin offset from 45 to 75 degrees in hope of creating a smoother-running motor. But just as production began, American Suzuki engineers decided that the new offset resulted is less mid-range power as well as a too-sanitized exhaust note, one that didn't sound very V-Twin-like. Presto, now the US models come with the 45-degree offset, while the rest of the world gets the 75-degree staggered crankpins.}}</ref>

=== V angles ===

Generally, any two-cylinder motorcycle engine with its two cylinders arranged more than 0° and less than 180° apart is referred to as a V-twin. The V-twin engine is not designated by a specific angle, but is often associated with narrow V angles of 42° to 50° as the classic V-twin configuration. Any narrower could cause unwanted vibration, any wider and the chassis would have to be too long.<ref>{{cite web |title=V-TWIN IMITATION and HISTORY |url=http:, , www.americanrider.com, output.cfm?id=2242657 |journal= American Rider |author= Clement Salvadori |accessdate=19 April 2010}}</ref>

A 90° twin engine, such as the signature [[Ducati]] engine — with the front cylinder approximately horizontal and the rear cylinder approximately vertical — is generally referred to by Ducati as a "L"-twin engine. There is no technical distinction between [[Ducati_V-twin_motorcycles#V-Twin_or_L-Twin| V-twin and L-Twin]] engines. These are merely names used by convention. 

When comparing common shared crank pin designs, the 90° V angle acts as a [[counterweight]] to provide primary [[Engine balance|balance]] to the engine, but the firing is uneven. Smaller angles give poorer mechanical balance, but more even firing for a four-stroke (but, even less even firing for a two-stroke). See external links for Shaking forces of twin engines by Vittore Cossalter.

{| class="wikitable"
|-
! V angle
! Examples
|- 
| 26° 
| [[Matchless]] Silver Arrow
|-
| 42°
| [[Indian (motorcycle)|Indian]] Powerplus, Chief, [[Indian Scout (motorcycle)|Scout]]
|-
| 45°
| [[Crocker Motorcycles]]<br>[[Harley-Davidson]]<br>[[Sokół 1000]]<br>Suzuki [[Suzuki VX 800|VX800]], Boulevard C50, Boulevard C90, Boulevard S50, Boulevard S83
|-
| 47.5°
| Vincent [[Vincent Rapide|Rapide Series A]]
|-
| 48°
| Yamaha [[Yamaha MT-01|MT-01]], [[Yamaha XV1600A|XV1600]], XV1700
|-
| 50°
| AJS [[AJS S3 V-twin|S3]]<br>BSA [[BSA Model E|Model E]], G14, Y13<br>[[Husqvarna Motorcycles]]<br>[[JA Prestwich Industries|J.A.P.]] for Brough Superior [[Brough Superior SS100|SS100]]<br>Kawasaki [[Kawasaki Vulcan 1500 Drifter|Vulcan 1500, 1600]]<br>Matchless [[Matchless Model X|Model X]]<br>[[Victory Motorcycles]]<br>Vincent [[Vincent Rapide|Rapide Series B, C]]
|-
| 52°
| Honda [[Honda Shadow|Shadow]], [[Honda Transalp|Transalp]], [[Honda Deauville|Deauville]]<br>Kawasaki [[Kawasaki Vulcan|Vulcan 1700 & 2000]],[[Honda XRV750|XRV750 Africa Twin]]
|-
| 54°
| Suzuki [[Suzuki Boulevard C109R|Boulevard C109R]], Boulevard M50, Boulevard M90, Boulevard M109R
|-
| 55°
| Kawasaki Vulcan [[Kawasaki Vulcan 800 Drifter|800]], [[Kawasaki Vulcan 900 Classic|900]]
|-
| 56.25°
| [[S&S Cycle|S&S]] X-Wedge Engine
|-
| 60°
| [[Britten V1000]]<br>[[Harley-Davidson VRSC]]<br>[[Rotax]] for Aprilia [[Aprilia RSV Mille|RSV Mille]], [[Aprilia Tuono|Tuono]]<br>Yamaha [[Yamaha XV250|XV250]], [[Yamaha DragStar 250|XVS250]]
|-
| 70°
| Yamaha [[Yamaha DragStar 650|XVS650]]
|-
| 72°
| [[Moto Morini|Moto Morini 350]]<br>[[Rotax]] for Buell [[Buell 1125R|1125R]]
|-
| 75°
| Hyosung [[Hyosung GT250|GT250]], [[Hyosung GV250|GV250]]<br>KTM [[KTM 1190 RC8|1190 RC8]]<br>Yamaha [[Yamaha XV920R|TR1]], [[Yamaha Virago|Virago]], [[Yamaha DragStar 1100|XVS1100]]
|-
| 77°
| [[Aprilia RXV, SXV]]
|-
| 80°
| [[Honda CX series]]
|-
| 87°
| [[Moto Morini|Moto Morini Corsaro 1200]]<ref>{{cite web |title=Motore |url=http:, , www.motomorini.com, web, #?id=motore& |accessdate=28 April 2010}}</ref>
|-
| 90°
| Aprilia [[Aprilia SL 750 Shiver|SL 750 Shiver]], [[Aprilia NA 850 Mana|NA 850 Mana]]<br>Bimota [[Bimota V Due|V Due]]<br>[[Briggs & Stratton]]<br>[[Ducati V-twin motorcycles|Ducati]]<br>Gilera [[Gilera GP 800|GP 800]]<br>Honda [[Honda VTR250|VTR250]], [[Honda VTR1000F|VTR1000]], [[Honda XL1000V Varadero|XL1000V]] & [[Honda XL125V Varadero|XL125V]] Varadero<br>Hyosung [[Hyosung GT650|GT650]], [[Hyosung GV650|GV650]]<br>Kawasaki [[Kawasaki Prairie 650|Prairie 650]], [[Kawasaki v-force|V-Force]]<br>[[Mazda V-twin engine|Mazda]]<br>[[Moto Guzzi]]<br>Suzuki [[Suzuki SV650|SV650]], [[Suzuki SV1000|SV1000]], [[Suzuki TL1000R|TL1000]], [[V-Strom]]
|-
| 120°
| 1934 [[Moto Guzzi]] 500cc
|-
| 170°
| [[Zündapp|Zündapp]] [[:de:Zundapp KS 601|KS 601]]
|}

== Orientations ==
The terms [[longitudinal engine]] and [[transverse engine]] are most often used to refer to the crankshaft orientation,<ref name="Cossalter">{{cite book
| title = Motorcycle Dynamics
| edition = Second Edition
| last = Cossalter
| first = Vittore  
| year = 2006
| publisher = Lulu.com
| isbn = 978-1-4303-0861-4
| pages = 291–294}}</ref><ref name="Foale">{{cite book
| title = Motorcycle Handling and Chassis Design: the art and science 
| edition = Second Edition
| last = Foale
| first = Vittore  
| year = Tony 
| publisher = Tony Foale
| isbn = 978-8493328634 
| pages = 11–6}}</ref>  however, some sources, most prominently [[Moto Guzzi]], use the terminology in the opposite way.  

A Moto Guzzi Technical Services representative tried to explain to LA Times columnist Susan Carpenter that Moto Guzzi engines are "called 'transverse' because the engine is mounted with the crankshaft oriented front to back instead of left to right."<ref>{{
 Citation |last=Carpenter |first=Susan|title=Chaps aren't de rigueur, but a helmet, yes|work=ASK THROTTLE JOCKEY |url=http://www.latimes.com/classified/automotive/highway1/la-hyw-qa25jul25,1,2706840.story |quote=
According to my source at Moto Guzzi Technical Services, "The Guzzi engine is a 90-degree 'L' twin, actually, because the cylinders are oriented at 90 degrees, instead of a typical V twin that has a smaller angle ( 60-degree, 77-degree, etc.). It is called 'transverse' because the engine is mounted with the crankshaft oriented front to back instead of left to right. Because of this you cannot run a chain or belt drive directly to the rear wheel like in most motorcycles. This is why you have a separate gearbox that bolts to the engine and transfers the power to the rear wheel via the drive shaft. This is how it is done on the Moto Guzzi and a BMW.
}}</ref>  In spite of this, it it could be assumed that those who call V-twin motorcycle engines  "transverse" when they are mounted with the crankshaft front-to-back and the cylinders sticking out the sides are saying that to them, the engine's axis is the line passing from one cylinder to the other, at a right angle to the crankshaft, rather than going by the crankshaft's axis.<ref name=Coombs>{{
 Citation |last1=Coombs |first1=Matthew  |last2=Haynes |first2=John |last3=Shoemark |first3=Pete |title=Motorcycle Basics | edition=2nd |publisher=Haynes | year=2002| page=1•31| ISBN 1-85960-515-X, 9781859605158 | url=http://books.google.com/books?id=D0DhHAAACAAJ | quote=The transversely mounted &#91;cylinder&#93; V-twin, as used to good effect for many years by Moto Guzzi, slots easily into the frame, and has excellent cooling as both heads are stuck out into the wind.  It also provides the perfect set-up for using shaft drive. |note=This book uses transverse to mean 'transverse cylinders' without regard to crankshaft orientation. 
}}</ref><ref>{{
 Citation |last=Holmstrom |first=Darwin  | author-link= |title=The Complete Idiot's Guide to Motorcycles |Edition= |year=2001 |publisher=Alpha Books |location= | url=http://books.google.com/books?id=VGrp5Pjsf4UC&pg=PA82 |isbn=0028642589, 9780028642581 | quote=Ducati's engines, which are longitudinal (they are positioned lengthwise in the frame) most obviously display the "L" configuration, but Moto Guzzi's engines, which are transverse (arranged croswise in the frame), are also at 90 degrees.   
}}</ref><ref>{{
 Citation |title=New 2009 Moto Guzzi V7 Classic Honors Historic Roots  | publisher=Moto Guzzi Spa  |url=http://www.motoguzzi-us.com/servonline/news/dettaglio.asp?indice=271   |accessdate=2009-04-29 | quote= Just as importantly, the V7 became an instant technology trendsetter thanks to its innovative transverse, air-cooled V-twin engine with shaft drive.   
}}</ref><ref>{{
 Citation |title=New 2009 Moto Guzzi V7 Classic Honors Historic Roots  | publisher=Moto Guzzi Spa  |url=http://www.motoguzzi-us.com/servonline/news/dettaglio.asp?indice=271   |accessdate=2009-04-29 | quote=We could, of course write a book about Moto Guzzi’s transverse V-Twin.  
}}</ref><ref>{{
 Citation |title=Breva V 1100  | publisher=Moto Guzzi Spa  |url=http://www.motoguzzi-us.com/Nuovi_modelli/breva1100/specifiche4.asp?pagina=spec&modello=breva1100&pag=4   |accessdate=2009-04-29 | quote= Just as importantly, the V7 became an instant technology trendsetter thanks to its innovative transverse, air-cooled V-twin engine with shaft drive.   
}}</ref><ref>{{
 Citation |title=A walk around the Breva V 1100 | publisher=Moto Guzzi Spa  |url=http://www.motoguzzi-us.com/Nuovi_modelli/breva1100/specifiche4.asp?pagina=spec&modello=breva1100&pag=4   |accessdate=2009-04-29 | quote=The transverse 90° V-Twin engine and its shaft drive were chosen not as limitations on the freedom of design, but as the very heart of the design concept. 
}}</ref><ref>{{
 Citation |last=Grubb |first=Jake |title=Easy Riders Grand Touring Motorcycles for '75 url=http://books.google.com/books?id=aeMDAAAAMBAJ&pg=PA82 |page=82 | periodical=Popular Mechanics | publisher=Hearst Magazines |volume=143 |issue=3 |date=March 1975 |accessdate=2009-04-29 |ISSN=0032-4558| quote=Ducati 750 Sport with its clip-on handlebars and racing setup, is for those who want to do their touring stretched out prone!  Engine is a longitudinal V-twin. ..The unique 90∘longitudinal engine produces enormous low and mid-range torque...Moto Guzzi 850T...An 850-cc 90 V-twin engine... 
}}</ref>  Highly technical sources, such as V. Cossleter's <I>Motorcycle Dynamics</I>,<ref name="Cossalter"/> or Gaetaeno Cocco's <I>Motorcycle Design and Technology</I><ref name=Cocco>{{Citation |title=Motorcycle design and technology |first=Gaetano |last=Cocco |]ublisher=MotorBooks/MBI Publishing Company |year=2004 |isbn=0760319901, 9780760319901 |pages=117 ff}}</ref> are careful not simply to use the terms "longitudinal engine" or "transverse engine," but rather to specify that they mark the engine's orientation based on the crankshaft, and so they will say "transverse crankshaft engine" or "longitudinal crankshaft engine."<!-- I would love to keep this reference but it seems to no longer exist.  It is the only known source that says Moto Guzzi and others are making a "mistake." 
A common mistake with V-2 engines is to refer to the cylinder orientation.<ref>{{cite web
| url=http://www.bmwmotorcycles.com/pdfs/history/design_tech.pdf|format=PDF|publisher=BMW Motorcycles
| title=Heritage/History: Design/Technology}}</ref> However referring to the crankshaft gives a correct method to engine orientations as it gives the same orientation for all V-engine types like V-2, V-4 (which would be difficult to describe with cylinder orientation) and V-8. Both two-cylinder V engines are common on [[motorcycle]]s. -->

=== Transverse crankshaft mounting ===
The engine can be mounted in transverse crankshaft position as on [[Harley-Davidson]]s, [[Ducati]]s and many recent Japanese motorcycles. This transverse position gives the motorcycle a reduced frontal area. The main disadvantage of this configuration is that the rear cylinder and the front cylinder will receive different air-flows making air cooling somewhat problematic especially for the rear cylinder.  Cooling problems are somewhat mitigated by having all "four" sides of each cylinder exposed to air flow.  This differs from a parallel-twin cylinder engine which has a distinct front, back, and sides, but the inside of each cylinder is not exposed to airflow as the cylinders are typically joined together with a cam chain running up through the block in-between the cylinders.
<gallery caption="Some cooling strategies of transverse-crankshaft 90° V-twins" widths="180px">
File:Ducati Monster 620 Dark.jpg|This air-cooled Ducati Monster 620 has a transverse crankshaft 90° V-twin with one cylinder laying horizontally, and one vertically, so that the rearward, vertical cylinder's air flow is less obstructed by the one in front.
File:HONDA VTR250 2003 Pearl Shining Yellow.jpg|Honda's VTR250 is similar, but the engine is not leaning forward, thus each cylinder is about 45° from vertical.  The rear cylinder's air flow is blocked, but note this is a water-cooled engine, so what most matters is that the radiator is out in front with good air flow.
File:Ducati Monster S4R Testastretta.jpg|As the Ducati models get larger engines, they gain oil-, and then water-cooling, as in this Monster S4R S. Like the VTR250, the radiators are out in front, but the basic engine orientation retains the cooling advantages of the Monster 620.
</gallery>

=== Longitudinal crankshaft mounting ===
The longitudinal crankshaft two-cylinder V as seen on [[Moto-Guzzi]]s and some [[Honda]]s is less common. This orientation is well suited for [[driveshaft|shaft drive]] by eliminating the need for a 90° [[bevel gear]] at the transmission end of the shaft.  In motorcycles, a longitudinal engine fits well inside the frame, and aids cooling because both heads protrude out into the air. <ref name=Coombs/>  However this approach has the slight disadvantage in motorcycles of causing a torque reaction that tends to lean the motorcycle slightly to one side as the angular rate of the crankshaft increases or decreases. The faster the change, the larger the torque it produces. However, many motorcycle manufacturers have corrected for torque reaction by rotating the transmission input shafts and/or the balance and drive shafts opposite that of the crankshaft so that there is approximately equal mass turning clockwise and counterclockwise at any time, thereby physically canceling the effect.

==See also==
*[[Flat-twin]]
*[[Motorcycle engine]]

==References==
{{reflist}}

==External links==
*[http://www.animatedpiston.com Detailed V Twin Engine Animations]
*[http://www.sense.net/~blaine/twin/twin.html Shaking forces of twin engines by Vittore Cossalter]


[[Category:Motorcycle engines]]
[[Category:Engine configurations]]