Interesting debate how a Vulcan V-twin is different than a HD V-twin

[ubernomad]

Originally Posted by glwilson

This is directly from Wikipedia; and is as an accurate description of why the sound is produced as one can explain. It is all here...
The classic Harley-Davidson engines are V-twin engines, each with a 45° angle between the cylinders. The crankshaft has a single pin, and both pistons are connected to this pin through their connecting rods.[9]

This 45° angle is covered under several United States patents and is an engineering tradeoff that allows a large, high-torque engine in a relatively small space. It causes the cylinders to fire at uneven intervals and produces the choppy "potato-potato" sound so strongly linked to the Harley-Davidson brand.

To simplify the engine and reduce costs, the V-twin ignition was designed to operate with a single set of points and no distributor. This is known as a dual fire ignition system, causing both spark plugs to fire regardless of which cylinder was on its compression stroke, with the other spark plug firing on its cylinder's exhaust stroke, effectively "wasting a spark". The exhaust note is basically a throaty growling sound with some popping. The 45° design of the engine thus creates a plug firing sequencing as such: The first cylinder fires, the second (rear) cylinder fires 315° later, then there is a 405° gap until the first cylinder fires again, giving the engine its unique sound.[102]

But correct me if I'm wrong isn't the Vulcan V-twin basically the same engine configuration? Single pin crankshaft. "Wasted" spark system. very close to 45 degree V angle (I think the Vulcan engine is something like 46 degrees??). Seems to me the Vulcan engine would have the same plug firing sequence with a slight difference due to the angle "V" being a little more than HD.

[glwilson]

Originally Posted by ubernomad

But correct me if I'm wrong isn't the Vulcan V-twin basically the same engine configuration? Single pin crankshaft. "Wasted" spark system. very close to 45 degree V angle (I think the Vulcan engine is something like 46 degrees??). Seems to me the Vulcan engine would have the same plug firing sequence with a slight difference due to the angle "V" being a little more than HD.

No.. Re-read all that's there. HD has a patent on their firing-sequence/timing of their engines. (This is not to be confused with their feeble attempt to patent the sound of their engines. This refers to the firing sequence. It is mentioned in the material on Wikipedia.)

Kaw is not the same despite it being a V-Twin. The V-Twin is just about all that is comparable between the two.

There are issues such as HD's 405 degree firing-gap occurring on the stroke cycle causing some of what you are referring to; along with a few other factors -- but the most noticeable is the firing-sequence with their engines is what you are hearing.

Older carbed engines are more often adjusted to a low-idle where you hear the stutter-step of the timing more so than the fuel-injected models. My previous and current FI HDs only slightly provide that sound when at idle. They simple do not idle slow enough for it to be noticeable.

Too bad Mac doesn't respond to this. He would be someone who could tell you what the Kaw V-Twin does in comparison.

[glwilson]

This 45° angle is covered under several United States patents and is an engineering tradeoff that allows a large, high-torque engine in a relatively small space. It causes the cylinders to fire at uneven intervals and produces the choppy "potato-potato" sound so strongly linked to the Harley-Davidson brand.

To simplify the engine and reduce costs, the V-twin ignition was designed to operate with a single set of points and no distributor. This is known as a dual fire ignition system, causing both spark plugs to fire regardless of which cylinder was on its compression stroke, with the other spark plug firing on its cylinder's exhaust stroke, effectively "wasting a spark". The exhaust note is basically a throaty growling sound with some popping. The 45° design of the engine thus creates a plug firing sequencing as such: The first cylinder fires, the second (rear) cylinder fires 315° later, then there is a 405° gap until the first cylinder fires again, giving the engine its unique sound.

[Loafer]

Originally Posted by glwilson

No.. Re-read all that's there. HD has a patent on their firing-sequence/timing of their engines. (This is not to be confused with their feeble attempt to patent the sound of their engines. This refers to the firing sequence. It is mentioned in the material on Wikipedia.)

Kaw is not the same despite it being a V-Twin. The V-Twin is just about all that is comparable between the two.

There are issues such as HD's 405 degree firing-gap occurring on the stroke cycle causing some of what you are referring to; along with a few other factors -- but the most noticeable is the firing-sequence with their engines is what you are hearing.

Older carbed engines are more often adjusted to a low-idle where you hear the stutter-step of the timing more so than the fuel-injected models. My previous and current FI HDs only slightly provide that sound when at idle. They simple do not idle slow enough for it to be noticeable.

Too bad Mac doesn't respond to this. He would be someone who could tell you what the Kaw V-Twin does in comparison.

[cnc]

Originally Posted by ubernomad

But correct me if I'm wrong isn't the Vulcan V-twin basically the same engine configuration? Single pin crankshaft. "Wasted" spark system. very close to 45 degree V angle (I think the Vulcan engine is something like 46 degrees??). Seems to me the Vulcan engine would have the same plug firing sequence with a slight difference due to the angle "V" being a little more than HD.

Good story but I doubt it is true. They may have looked at the design of one in building the 45 degree twin but certainly not modify one into a 2 cylinder. Radial aircraft engines are based on a odd number of cylinders around in a circle to get an even firing sequence. They could be 3,5,7 cylinders radiating around the circle and single or multiple rows. A 10 cylinder configuration would be 2 rows of five cylinders which would be 72 degrees apart. Also a radial aircraft engine is not a single pin crank, it has a master connecting rod that all the other connecting rods are attached to.