[nicholastanguma]

SS Cycle used to make a 60 degree v-twin crate engine, and Sputhe used to make a 60 degree v-twin crate engine, both without balance shafts and both of single crankpin design. Both companies claimed their engines were noticeably smoother in operation than Harley-Davidson v-twins.

So, then, imagine two Sportster engines of exactly equal bore/stroke, compression, timing, fueling, single crankpin design, absolutely everything...

...except degrees of separation between the cylinders. Imagine one engine was the traditional 45 degrees, and the other was 60 degrees.

Would the 60 degree Sportster mill actually produce less vibration to the point it's an undeniably better engine? You know, less rider fatigue, less mechanical fatigue, more hp potential, etc.

[GlennF]

A 45 degree V twin is not that much different to a parallel twin really.

Note that the Harley Davidson V-Rod was a 60 degree twin.

[Carl Fenn]

I can’t really comment on that only ever owned parallel twins or fours.

[AzCal Retred]

"Ducati - the Thinking Man's Harley..." 

https://www.motorcyclistonline.com/1978-ducati-900-gts-thinking-mans-harley/

[Karl Childers]

Modern Harley V twins are either rubber mounted as in the touring line or the engine is counter balanced and solid mounted for the Softails. Both systems lets them get away with their traditional engine configuration without a lot of vibration reaching the rider

[axman88]

Why stop at 60 degrees, when there are plenty of examples of single pin designs with other angles, up to 180 degrees?

I think that Fabio Taglioni's  90 degree V, or "L Twin, as Ducati preferred to call it, was an outstanding example. https://www.wikiwand.com/en/Ducati_L-twin_engine

But, there's lot lots more to consider, like how engine space requirements will constrain the overall design, intake and exhaust configuration, and manufacturing cost considerations such as whether parts can be shared between front and rear ( left and right for transverse mounted V's ) cylinders.

Maybe a more easily resolved comparison would be to compare single pin designs with dual pin?  45 degree 1100 cc engines were put into Honda Shadows that are comparable in all respects except crank pin count.  https://en.wikipedia.org/wiki/Honda_VT1100

Also, there are lots of parallel twin engine configurations to consider.  https://motorcyclemojo.com/2014/09/crankshafts-and-firing-orders/

One can explore primary vibration of different configurations for themselves using 3D modeling software that allows dynamic simulation.  Solidworks will do this.  I don't know if there is any free software available that does this, but I wouldn't be surprised if there was.

[cyrusb]

I have lived with quite a few Harleys and Ducatis and have found its all about the balance factor. The Ducs were almost always very well balanced right out the factory. I had a 750 that was almost a turbine!
 The Harley Sportsers I had were another thing. Hit or miss balance wise. However I had a super vibrating 77XLH that I had a very expensive dynamic balancing act done on and after it was almost as smooth as a Ducati L twin. I have to add that I got this bike cheap because it vibrated so bad at 40 mph  you developed double vision. Do any of these balance magicians still exist? My guy was a 70 year old cigar chewing Garfield NJ basement shop dweller. Here is a shot of 2 well balanced machines.

[gizzo]

"Ducati - the Thinking Man's Harley..." 

https://www.motorcyclistonline.com/1978-ducati-900-gts-thinking-mans-harley/

I object to that on a couple of levels :that they assume I'm a thinking person, and that they compare my bike of choice with a Harley 😂

[GlennF]

The Guzzi V7's are also a 90 degree V Twin.

I suppose you could call teh old BMW Boxers and the Ural's a 180 degree V Twin whereas the Bonneville would be a 0 degree V twin.

[axman88]

Folks might be interested in reading this article that discusses some of the elements of engine primary balance, cylinder Vee angle, crankpin locations, and more.  The author talks about why Sportsters shake in the way they do, why original Ducatis had a long wheelbase, why some manufacturers choose angles other than 45 or 90 degrees, and much, much more.

https://www.cycleworld.com/2016/02/01/motorcycle-v-twin-and-parallel-twin-and-flat-twin-engine-tech-sound-insights/

I would find it interesting to see a list of machine engines with Vee angle, crankpin angle, and whether or not a balancer shaft is incorporated, but this sort of information can be laborious to compile.  I find myself searching for pictures of replacement cranks to figure out crankpin angle, because that number doesn't generally appear on any spec. sheet.  All of the machines I currently ride use a single crankpin design, including a Honda Shadow 1100 ACE from the mid 90's that, according to the folk history, caught Harley's attention and prompted them to file their "Potato, potato" lawsuit to copywrite the single crankpin, 45 degree engine sound.   Harley's copywrite attempt failed.

What I find remarkable about this Honda 1100 ACE engine, is that, prior to 1995, all Honda 1100 engines had dual crankpins.  When they switched to single crankpin, Honda retained a 3 disc forged crankshaft.  There was no practical design or manufacturing reason for them to make the change, it was 100% marketing driven.  To achieve the american iron styled "loping idle" and "rumbling" sound, Honda gave up 10 horsepower, and 10 ft-lbs of torque, and PAID development money to do this.  Despite the increased vibration, or maybe because of it, USA riders bought these machines, (which were built in Honda's factory in Ohio), by the carload, they were very popular.  Which just goes to prove, better is, as better SELLS!   After around 1998, some models of VT1100s were sold with single crankpin, while others were built with dual crankpin.

[axman88]

A couple more links that might be of interest to folks reading this thread:

The "Tractor and Construction plant Wiki", of all places, includes a list of moto engines with various cylinder angles, 20 different angles included from 26 to 170 degrees.  I see the Honda Vee twins seem underrepresented.    https://tractors.fandom.com/wiki/V-twin_engine

This page shows the shaking force equations and presents animated models of various configurations   http://sense.net//~blaine/twin/twin.html

The models look like Mathcad.  I wonder if that is still around?

[AzCal Retred]

These are all great links, and if "Folks" actually wanted to bootstrap hisself into more knowledge, "Folks" would really study on them. Maybe then "Folks" would start pre-screening some of their questions, perhaps prefacing them with "X and Y say this about topic "Z", but I'm not quite making the full connection yet..." That would denote educational progress, not boredom.
Physics & Chemistry are pretty well sorted out by now. It does however take a small box of mathematical skill to fully benefit from the knowledge. "Apply what you know to figure out what you don't"

Those Honda examples are great, if ever there was a mechanical engineering based company, they're it. In the wayback they were using torsion bars for valve springs on the mass production, venerable old CB450 "Black Bomber". The NS500 was artwork, and of course the multi cylinder GP efforts of the 1960's.

[Karl Childers]

The NS500 was artwork,

Oval pistons if I recall right.

[GlennF]

Way back in the 70's I started an engineering degree (which I dropped out of half way through to pursue a "more interesting lifestyle" for a while and never went back) and we spent a lot of time on (very expensive) analogue computers modelling this sort of stuff using differential equations.  There are no algorithms or code in an analogue computer you patch in modules that are integrators and differentiators and set variables with potentiometers. Not a keyboard to be seen.

This is an analogue computer:

[cyrusb]

So, the answer to the original question is?
 My take is all configurations can be well balanced.
 The quality of the balance is important. Imperical/stactic methods have limits.
 An unbalanced engine will always make less power than a well balanced one.
 The 45 degree angle with Harleys ignition timing approaches the power impulses of a large single. Take a sporty on a dirt road and goose it. It will leave a dotted line. Very helpful in dirt oval competitions, as it allows the tire to rebite.