Parallel Twin

[V4]

What is the difference in a 'parallel twin' and a 'vertical twin' engine.  I thought I knew but after a recent conversation with a Harley mechanic I am now not so sure.  

[BEAMA]

A vertical twin has vertical barrels. ie the triumph 5ta etc
they are also parallel. ie barrels alongside each other.
A parallel twin can have barrels at any angle as long as the two cylinders are alongside each other. ie the 125 cc moto rumi twin.

[vfactory]

V4 what did the HD mech say anyways??

[V4]

A vertical twin has vertical barrels. ie the triumph 5ta etc
they are also parallel. ie barrels alongside each other.
A parallel twin can have barrels at any angle as long as the two cylinders are alongside each other. ie the 125 cc moto rumi twin.

Bema, Thanks for this, finally someone has made it absolutely clear as the definitions have somehow seemed to become one, that is a parallel twin being a vertical twin.  

[V4]

V4 what did the HD mech say anyways??

vfactory,
At the moment I am in a remote area of Northern Ontario Canada with a very slow Internet connection.  Will reply in detail when I return to civilization!!

[V4]

vfactory,
At the moment I am in a remote area of Northern Ontario Canada with a very slow Internet connection.  Will reply in detail when I return to civilization!!

Bema has already made it clear the difference between  parallel and vertical twins.  My querry came after reading a report in a magazine of how the Japanese have virtually eliminated "rocking couple" in their twins be it parallel or vertical, a symptom that supposedly plagued the early British twins.  I have a 1983 Honda CM 250C that Nigel has posted in the photo gallery under photos by manufacturer-Honda.  It is a parallel twin with a 360 degree crankshaft.  I visited a local Harley shop and asked the mechanic the difference between a parallel and vertical twin-he had no idea.  I live in Oshawa Canada east of Toronto and deeply embedded into Harley territory.  Further dialogue on the subject revealed that "rocking couple" is agravatted by rod spacing and crankshaft length leading to twisting of the crank and the cases and is typically more associated with 180 degree crankshafts.