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

[ubernomad]

I'm a very curious sole. I love to learn about things. One of the things I've been digging into lately is why/how the unique sounding Harley Davidson V-twin engine sounds so much different compared to the sea of Japanese "metric" V-twin engines. Google searches turned up all kinds of info, correct or not, but I stumbled across this discussion which had me thinking about how the 1500/1600 Vulcan engine operates compared to the Harley Davidson engine. Both are single pin cranks. Both are fuel injected. Both a narrow angle V-twins.

So, for those who care to share.....why doesn't the Vulcan V-twin engine sound anything like a similar H-D v-twin?

http://www.justanswer.com/motorcycle/6zlat-sound-hd-music-it-s-not-potato-potato-thing.html


It's not the potato potato thing that makes me curious. That's a simple explanation.

My question is -- and no one has ever been able to provide a really good answer:

The HD V-Twin, while at idle, has a noticeable 'miss' or a 'pause' every few cycles.

We love the idle sound and cadence. We agree it's unique. Other single pin crank V Twin bikes don't have the HD cadence at idle. We don't understand why.

Whatever you want to call it: Skip. Misfire. Pause. Lope. Cadence.
Why does it do it.
And HOW does it do it.

If it is a "designed-in" random idle misfire to get that cadence - how does HD get away with it.

Listen to any Harley at idle. Carb, FI, stock or custom pipes, doesn't matter. At idle, every few rpms, it "skips" a beat, sounds irregular. I'm not talking about the natural uneven firing rythm due to the single throw crank. I'm referring to the "SKIP". The resulting rolling sound is wonderful.

What causes it. I can understand sloppy carbueration on the older models, an occasional 'hiccup' at idle.

Even the modern Harley FI motors, the ones supposedly so carefully computer controlled... how can they have that idle 'skip' or hiccup. To me, seems impossible. Or implausable.
My 2011 103" Street Glide is fuel injected, yet idles like an old carbuerated model. I love it. But with modern fuel injection, just don't understand how it can happen. Properly running fuel injected engines simply don't misfire at idle.

But mine does, and so does every other Harley on the planet.

A designed-in idle misfire? To create the unique rolling idle sound with the occasional skip?
Just can't see any way an idle misfire could sneak past EPA. The HC ('unburned') emissions would blow off the scale.

I grow weary of tired old explanations like "it's the pushrods" or "the unique HD valve angle", it's all a bunch of nonsense. Those things by themselves don't make an engine occasionally miss a beat at idle. It has to be something associated with fuel and or ignition delivery at IDLE, maybe combined with some weird cam overlap profiles, to produce the irregular sound. Something is causing the engine to skp a beat, to produce the Harley stutter step idle quality. So, what is it.

Answer according to the "expert":

the cause of the miss at idle....and occasionally when riding....is the result of the way the entire engine is designed, not just the common crank pin.

the problem comes from the "siamesed" intake system. this does two things. first, it causes the front cylinder to run leaner than the rear and occasionally results in an upset of the air flow to the rear cylinder, resulting in a lean mis-fire.

it causes the front cylinder to run leaner than the rear due to a combination of the valve timing. it was designed this way to account for the front cylinder receiving fresh cooling airflow and the rear cylinder receiving warmer airflow off the font cylinder. most people mistakenly assume the rear cylinder runs hotter than the front on a Harley. it does not. it was designed to run cooler.
the issue exists in fuel injected bikes, but is controlled by the ability of the fuel injection to offer a different air/fuel mixture to each cylinder.

the lean mis-fire will always exist in 4 degree V twin Harleys. even fuel injection cannot compensate for the occasional air flow disturbance to the rear cylinder.
basically....the air is drawn into the common intake and then must either go right or left, in uneven intervals and, during valve overlap there is another airflow component which is exhaust from front to rear or rear to front. occasionally, the airflow to the rear cylinder stalls.
the fuel injection can only provide a fuel injector pulse for the anticipated air flow when the intake valve opens, but it cannot compensate when the airflow gets disturbed at that moment and only for a fraction of a second.
this effect is more evident on older models with points triggered ignitions idling at about 600 rpm. an added affect in that system is that when the cylinders fire, the crank is accelerated and the advance flyweights open up and advance the ignition, then the flywheels coast down to the next power pulse and the flyweights pull in, retarding the spark.
the issue, although still prevalent with electronic ignitions, is less noticeable due to a constant advance input at idle and by setting the idle rpm to 1,000 rpm.


I'm trying to wrap my head around how these engines operate from a engineering/design standpoint.

[Sparks500]

I still think Harley engines started out as scrap air compressors........

[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]

Harley-Davidson has used various ignition systems throughout its history – be it the early points and condenser system, (Big Twin up to 1978 and Sportsters up to 1978), magneto ignition system used on some 1958 to 1969 Sportsters, early electronic with centrifugal mechanical advance weights, (all models 1978 and a half to 1979), or the late electronic with transistorized ignition control module, more familiarly known as the black box or the brain, (all models 1980 to present).

Starting in 1995, the company introduced Electronic Fuel Injection (EFI) as an option for the 30th anniversary edition Electra Glide.[103] EFI became standard on all Harley-Davidson motorcycles, including Sportsters, upon the introduction of the 2007 product line.[104]

In 1991, Harley-Davidson began to participate in the Sound Quality Working Group, founded by Orfield Labs, Bruel and Kjaer, TEAC, Yamaha, Sennheiser, SMS and Cortex. This was the nation's first group to share research on psychological acoustics. Later that year, Harley-Davidson participated in a series of sound quality studies at Orfield Labs, based on recordings taken at the Talladega Superspeedway, with the objective to lower the sound level for EU standards while analytically capturing the "Harley Sound."[citation needed] This research resulted in the bikes that were introduced in compliance with EU standards for 1998.

On February 1, 1994, the company filed a sound trademark application for the distinctive sound of the Harley-Davidson motorcycle engine: "The mark consists of the exhaust sound of applicant's motorcycles, produced by V-twin, common crankpin motorcycle engines when the goods are in use". Nine of Harley-Davidson's competitors filed comments opposing the application, arguing that cruiser-style motorcycles of various brands use a single-crankpin V-twin engine which produce a similar sound.[105] These objections were followed by litigation. In June 2000, the company dropped efforts to federally register its trademark.[106][107]

[glwilson]

I still think Harley engines started out as scrap air compressors........

No they let the Metrics do that...:lmao::cheers:

[ubernomad]

I still think Harley engines started out as scrap air compressors........

:D

My Vulcan 1600 sounds a lot like my v-twin 23 HP riding lawn mower.


It's weird because my father just bought a 2014 HD Dyna Low Rider. He was over yesterday and we were comparing how my bike and his bike sound soooo much different. You definitely notice the "bang-bang...pause...bang-bang...pause" sound of his engine. The VN1600 has a much more even sounding bang-bang-bang-bang sound at idle (when it does idle). Very even firing order. The HD engine has a very pronounced "miss" as everyone puts it.

Does anyone have any technical info on the engine dynamics for the Kawasaki engine?

[HwyRider]

52 degree v-twin

[ubernomad]

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.

[hayes]

The original hd was made from a 10 cylinder plane engine. You get that sound because the crank is still based of ten cylinders. You get fire on 1 then 2 but then you have 8 missing fires. That's the "hesitation" you're hearing.

I was told that by a Harley historian and it made sense. I have no idea if it's true, but I believe it...

[ubernomad]

52 degree v-twin

Wikipedia says the 1600 engine is 50 degree V-twin. 1700 and 2000 series are 52 degree.


So, would that slight difference in V angle cause the firing order to be more "even" considering it is still a single pin crankshaft?

[dabull]

seems to me its the aftermarket pipes that make it sound like a HD.... most stock HDs sound nothing like the potato potaatoo .....

[ubernomad]

The original hd was made from a 10 cylinder plane engine. You get that sound because the crank is still based of ten cylinders. You get fire on 1 then 2 but then you have 8 missing fires. That's the "hesitation" you're hearing.

I was told that by a Harley historian and it made sense. I have no idea if it's true, but I believe it...

That makes no sense to me. It's a 4-stroke engine. You wouldn't have 8 missing firings unless they purposely skip power strokes by disabling spark or fuel.

[ubernomad]

seems to me its the aftermarket pipes that make it sound like a HD.... most stock HDs sound nothing like the potato potaatoo .....

I've got VH baggers on my Nomad and it sound NOTHING like a Harley v-twin regardless of speed. Mine has a very even pop-pop-pop-pop sound while his Dyna Low Rider has a more uneven sound. It does sound like it is designed to miss a power stroke firing where the Vulcan engine fires on ever power stroke.

[glwilson]

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.

[hayes]

That makes no sense to me. It's a 4-stroke engine. You wouldn't have 8 missing firings unless they purposely skip power strokes by disabling spark or fuel.


It's easier to explain if I can show you with my hands. It's not actually missing but there is a longer distance between cylinder 2 and 1 then there is between 1 and 2 (in order of fire). You can make that happen with a 4 stroke. It's not actually missing.

Like I said. Could be hogwash. Makes sense to me though.

[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.

[jlreeves]

I've always thought my 1600 motor with V&H duals/UB sounded just like the 327 Chevy Camaro motor I used to have. Others have said the same thing. The Harley guys actually call me V8 when I ride with them.

[Loafer]

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.


http://i1080.photobucket.com/albums/j323/glmjgm/cool%20bro.jpg (http://s1080.photobucket.com/user/glmjgm/media/cool%20bro.jpg.html)

[cnc]

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.

[hayes]

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.


Good to know. I wish I could remember where I heard that. Oh well. No skin off my back. And people believe it, even the Harley riders. 😉

[blowndodge]

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]

Harley-Davidson has used various ignition systems throughout its history – be it the early points and condenser system, (Big Twin up to 1978 and Sportsters up to 1978), magneto ignition system used on some 1958 to 1969 Sportsters, early electronic with centrifugal mechanical advance weights, (all models 1978 and a half to 1979), or the late electronic with transistorized ignition control module, more familiarly known as the black box or the brain, (all models 1980 to present).

Starting in 1995, the company introduced Electronic Fuel Injection (EFI) as an option for the 30th anniversary edition Electra Glide.[103] EFI became standard on all Harley-Davidson motorcycles, including Sportsters, upon the introduction of the 2007 product line.[104]

In 1991, Harley-Davidson began to participate in the Sound Quality Working Group, founded by Orfield Labs, Bruel and Kjaer, TEAC, Yamaha, Sennheiser, SMS and Cortex. This was the nation's first group to share research on psychological acoustics. Later that year, Harley-Davidson participated in a series of sound quality studies at Orfield Labs, based on recordings taken at the Talladega Superspeedway, with the objective to lower the sound level for EU standards while analytically capturing the "Harley Sound."[citation needed] This research resulted in the bikes that were introduced in compliance with EU standards for 1998.

On February 1, 1994, the company filed a sound trademark application for the distinctive sound of the Harley-Davidson motorcycle engine: "The mark consists of the exhaust sound of applicant's motorcycles, produced by V-twin, common crankpin motorcycle engines when the goods are in use". Nine of Harley-Davidson's competitors filed comments opposing the application, arguing that cruiser-style motorcycles of various brands use a single-crankpin V-twin engine which produce a similar sound.[105] These objections were followed by litigation. In June 2000, the company dropped efforts to federally register its trademark.[106][107]

This is 100% correct. My concern was both rods sharing a common crank pin. One rod passes through the other. Seems to me like a lot of stress on that one crank pin. Obviously it works. Triumph Thunderbird as two pins but is staggered like Harley and sounds almost identical at idle.

It was foolish to try to trademark it's sound.

[cactusjack]

If you want a bike that sounds like a Harley, you could do as many of us have and go buy yourself a Harley. :D

[cnc]

Good to know. I wish I could remember where I heard that. Oh well. No skin off my back. And people believe it, even the Harley riders. 😉

Yeah sounds plausible till you do a little geometry. I could not find any reference to the story even as an urban legend.

[ubernomad]

If you want a bike that sounds like a Harley, you could do as many of us have and go buy yourself a Harley. :D

This isn't about "wanting" a Harley. I don't. I'm just curious why the metric V-twin engines sound nothing like a H-D engine.....from an engineering/design standpoint.

[macmac]

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]

Harley-Davidson has used various ignition systems throughout its history – be it the early points and condenser system, (Big Twin up to 1978 and Sportsters up to 1978), magneto ignition system used on some 1958 to 1969 Sportsters, early electronic with centrifugal mechanical advance weights, (all models 1978 and a half to 1979), or the late electronic with transistorized ignition control module, more familiarly known as the black box or the brain, (all models 1980 to present).

Starting in 1995, the company introduced Electronic Fuel Injection (EFI) as an option for the 30th anniversary edition Electra Glide.[103] EFI became standard on all Harley-Davidson motorcycles, including Sportsters, upon the introduction of the 2007 product line.[104]

In 1991, Harley-Davidson began to participate in the Sound Quality Working Group, founded by Orfield Labs, Bruel and Kjaer, TEAC, Yamaha, Sennheiser, SMS and Cortex. This was the nation's first group to share research on psychological acoustics. Later that year, Harley-Davidson participated in a series of sound quality studies at Orfield Labs, based on recordings taken at the Talladega Superspeedway, with the objective to lower the sound level for EU standards while analytically capturing the "Harley Sound."[citation needed] This research resulted in the bikes that were introduced in compliance with EU standards for 1998.

On February 1, 1994, the company filed a sound trademark application for the distinctive sound of the Harley-Davidson motorcycle engine: "The mark consists of the exhaust sound of applicant's motorcycles, produced by V-twin, common crankpin motorcycle engines when the goods are in use". Nine of Harley-Davidson's competitors filed comments opposing the application, arguing that cruiser-style motorcycles of various brands use a single-crankpin V-twin engine which produce a similar sound.[105] These objections were followed by litigation. In June 2000, the company dropped efforts to federally register its trademark.[106][107]

I didn't respond since this covers 99%. Dead spark the firing order which is strange on the HD, the cams, the push rods versus over head cams. HD cams are totally different for the over heads, and i really doubt the jug angles make a bit of difference.

I also didn't know that HD were based off radial engines, and so were missing 8 clys. I see some have confused that to think time is spaced missing 8 clys.. it's not missing them in time, they just are not there but then the cams are not made for the 8 missing clys either.

Last I knew the HD connecting rod was one piece and carried 2 pistons.

And don't confuse rotary engines with radial. A vintage rotary engine has a fixed crank shaft, and the jugs all whirl about the fixed crank.

https://www.youtube.com/watch?v=atMn9s6m-j4

[macmac]

Radial not rototary. These turned OFF look similar but are nothing alike really.

https://www.youtube.com/watch?v=HGKXdYCksAQ

[macmac]

So 'IF' the HD engines are take offs of radial engines they are missing some JUGS, but are camed for 2 jugs, but I do not 'KNOW' that as fact.

[OldSchool]

The original hd was made from a 10 cylinder plane engine. You get that sound because the crank is still based of ten cylinders. You get fire on 1 then 2 but then you have 8 missing fires. That's the "hesitation" you're hearing.

I was told that by a Harley historian and it made sense. I have no idea if it's true, but I believe it...

V Twins were around way before airplanes ever flew.

http://en.wikipedia.org/wiki/V-twin_engine

[Sparks500]

I'm no mechanic, but, a few years back I read an article about this same thing. They did mention the simultaneous firing plugs and the fact that most, if not all, metric v-twins have 4 valves per cylinder compared to Harley's 2.
Harley's do have a nice sound, I'm just leery of an engine without an oil sump.

[a340driver]

Interesting ...

[macmac]

I'm no mechanic, but, a few years back I read an article about this same thing. They did mention the simultaneous firing plugs and the fact that most, if not all, metric v-twins have 4 valves per cylinder compared to Harley's 2.
Harley's do have a nice sound, I'm just leery of an engine without an oil sump.

Dry sump works upside down, and so is no problem at all. This may have come to be in WW-1 for air planes but I don't know that is the reason. Porsche 911's had that system and maybe still do.

[ubernomad]

I'm no mechanic, but, a few years back I read an article about this same thing. They did mention the simultaneous firing plugs and the fact that most, if not all, metric v-twins have 4 valves per cylinder compared to Harley's 2.
Harley's do have a nice sound, I'm just leery of an engine without an oil sump.

The newer 2014 model year Twin Cam 103 motor in my father's Dyna LR is not a wasted spark design....it has dual (2) coils for true 1-2 firing just like the Vulcan engine. One coil for front cylinder and one for the rear cylinder. But it still sounds like a Harley should, which leads me to believe the ignition system (aka wasted spark) does not contribute to the HD sound. According to what I've read HD has moved away from the wasted spark design due mostly to emissions control and the fact that modern day electronic ignition systems are pretty darn reliable. The only reason they used the wasted spark design was to simply production, reduce cost, and provide a more "reliable" ignition system by having only one coil and no distributor.

[ponch]

This is 100% correct. My concern was both rods sharing a common crank pin. One rod passes through the other. Seems to me like a lot of stress on that one crank pin. Obviously it works. Triumph Thunderbird as two pins but is staggered like Harley and sounds almost identical at idle.

It was foolish to try to trademark it's sound.

The flywheels are pressed on the crank too. If revved to vigorously, I've read that they become other than perpendicular to the stub shafts creating runout. They could really improve the drivetrain with a unitized block and a one piece crankshaft.

[ponch]

So 'IF' the HD engines are take offs of radial engines they are missing some JUGS, but are camed for 2 jugs, but I do not 'KNOW' that as fact.

There's been a three cylinder too: http://www.motorcyclecruiser.com/make-mine-triple-feuling-w3

[macmac]

There's been a three cylinder too: http://www.motorcyclecruiser.com/make-mine-triple-feuling-w3

That's cool...:D

[Jllm02199]

That makes no sense to me. It's a 4-stroke engine. You wouldn't have 8 missing firings unless they purposely skip power strokes by disabling spark or fuel.

On Harley both cylinders fire on the same cycle. 45 degrees apart.

[Navigator]

Very interesting thread. Historically the "potato-potato" sound described the panhead/shovelhead. My 78 FLH shovel had a distinctively different sound than my 1988 Evo Electra Glide and my present 2002 Dyna Twin Cam 88. All have that common "hesitation" and all sound great. An old Harley guy can recognize the sound of a shovel starting up and idling without seeing it. The Evo and TC not so much. And unlike the Evo or Twin Cams, the shovel can idle at a lower RPM without the possibility of engine damage which somewhat contributes to the difference.

I am curious about the firing sequence discussion. I installed a Crane Hi-4E single fire coil on my Evo and expected it to change how it idled and sounded. It did not. Now I'm curious.

As an aside, the 2-1 Thunderheader for my Dyna Super Glide arrives Thursday and I'm looking forward to see how it sounds and performs.

[smokey]

funny but when I called Cobra to complain about the poor fit and backfiring I was getting with the tri ovals, their smart ass answer was that a lot of people want that Harley sound, my smart response was that if I wanted that Harley sound I would have got a Harley. Personally I find Harleys are too cramped for me, which is why I chose the Voyager.

[macmac]

Wise ass ? HD engine are not like Vulcan engines ..... Sort of like a chevy V8 350 isn't like a Toyota Tundra V8.

[ponch]

funny but when I called Cobra to complain about the poor fit and backfiring I was getting with the tri ovals, their smart ass answer was that a lot of people want that Harley sound, my smart response was that if I wanted that Harley sound I would have got a Harley. Personally I find Harleys are too cramped for me, which is why I chose the Voyager.

I haven't found them that much different. The pillion has more room on a HD, the rider slightly less, but with the HD, the tourpak can be moved back and there are a lot of options to change the ergonomics.

[KURT44]

I also found the Voyager to have more room to stretch out than the Ultra. I have seen reports where they say just the opposite. The bars might be wider on the Voyager. To each his own I guess. Also love the heal toe shifter on my 900 and Voyager. You can actually use them.

[ponch]

I also found the Voyager to have more room to stretch out than the Ultra. I have seen reports where they say just the opposite. The bars might be wider on the Voyager. To each his own I guess. Also love the heal toe shifter on my 900 and Voyager. You can actually use them.

It depends on your ergonomic requirements. Both bikes are more cramped for me than a 1600 Nomad. It that sense, it was a step backwards.

[andyvh1959]

On Harley both cylinders fire on the same cycle. 45 degrees apart. Yes, but, no. The cylinders are 45 degrees apart, and on a "dual spark or wasted spark" ignition system both plugs fire together but not 45 degrees apart. The combustion stroke of a 4-cycle v-twin with dual/wasted spark ignition, and a shared air/fuel intake system is what creates the sound. Some say the valve system has influence on the sound. Nope. 2-valve or 4-valve heads, pushrod valves or overhead cam valves heads have no impact on the sound.

Its the odd firing order of a Harley; 1st cylinder combusts the air/fuel mix and 315 degrees of engine rotation later the 2nd cylinder combusts the air/fuel mix. In between is the partial combustion we can hear during the wasted spark in the cyclinder with the exhaust valve slightly open. That also creates a sound pulse in the intake. So we can hear each specific combustion event out the exhaust. That, and the fact that many Harleys get that air/fuel mix into the cylinders through one shared intake system, whether that's one carb or one fuel injector. On a 45 degree v-twin it is tough to package two carbs, two intake runners, or two FI throttle bodies between the cylinders. Spread the cylinders out a bit, 50 degree VN1600 or 52 degree VN1700 and there is more room for dual intake systems. Also, water cooled v-twins don't have the required large diameter cooling fins. Vulcans have fins on the cylinders (mostly for looks), but the diameter is much smaller, allowing room for carbs or throttle bodies.

But a Harley, 45 degree v-twin, with two carbs, nothing else changed sounds unique to the same 45 degree v-twin with one carb. The sound of a twin air intake 45 degree Harley is much closer to the sound of a VN1600:

Here is an easy way to compare the sound difference:
1st, stock Harley one carb: https://www.youtube.com/watch?v=rsTmt3pUV9w
2nd, piped Harley XR1200: https://www.youtube.com/watch?v=i7yXKbYyKNM
3rd, Harley XR1000 two carbs: https://www.youtube.com/watch?v=FwlYp_X6yUg
https://www.youtube.com/watch?v=wRcpdy9ziVA

Now, compare that 3rd one with a VN1600: https://www.youtube.com/watch?v=CLnFQX_q4fc

Takes a bit of audio discernment, but I hear a similar sound pulse from the dual carbbed XR1000 and the VN1600. Also, doesn't matter that I used a Sportster to compare with the 1600. The larger Harleys and the Sportster both have 45 degree v-twin engines and single air intake systems. There are some twin carb conversions for Shovelheads, but no sound tracks that I've found.

[ponch]

I think Twin cam and later use single fire as do later sportsters.

[DragonLady58]

Yea, been sitting here on the fence, having a good laugh....
For anyone thats interested, theres a documentry about H-D on Prime....shows where the first engines were made, little more than glorified bicycles.
Also, the first Harley singles. After a few years, H-D and Indian were fighting on the tracks....
There were just a couple of parts that were in common with the radial aircraft engines, like the forked con-rods, and the lifter blocks....they were just a common design thing....
As far as sound, its a combo. of things....gotta remember these things were of old early 19th century design. Harleys sound is protected, they filed a lawsuit against a metric mfg'er for copying their sound. All they did was idle the bike up a few hundred rpms, and they got around that....they also changed their mufflers to also back away from that protected sound....
At that time Harley-Davidson had the not so big of a engine, so, the metrics (displacement wise) were bigger than the H-D's, also were water cooled....
The big kawa's, yama's, honda's, suzu's could run all day, everyday at interstate speeds, pulling 2 up, loaded to the hilt with travel gear, pulling a trailer, even up mountains....Harleys engines were being left in the dust, so-to-speak.
After taking big hits in sales bigtime, they went with the bigger engines, that led to rubber mounts, and all the modern stuff to try and get their sales back....
Its all been well documented....but Harleys big down fall with the metrics was reliability.

How many Harleys were bought with 50-85,000k on the clock, just cleaned up, tuned up, once checked out, folks touring the country with trips of 5,000k, not needing anything other than gas and oil.
Modern metric cruisers were of the 1400/1500/1600 sizes....totally reliable....Harley had to evolve, or die.
They've been carried by all the old timers like me, and their American Legend statis....Your buying the Harley-Davidson name....

https://www.rideapart.com/news/272616/honda-shadow-ace-harley-davidson-lawsuit/
https://www.thedrive.com/article/11345/remember-when-harley-davidson-sued-honda-for-being-too-harley
https://auto.howstuffworks.com/question325.htm
https://www.amazon.com/Harley-Davidsons-Season-1/dp/B01L7X2XE4


This should cover most everything....

[Brock]

The reason for harley sound https://www.cycleworld.com/story/blogs/ask-kevin/con-rod-confidential/

[Brock]

https://www.cycleworld.com/resizer/_gBiVw2XSqk6GemvmKUMWpzd1z0=/616x0/smart/cloudfront-us-east-1.images.arcpublishing.com/octane/VBIVDRWN4NESPC33GSNBVSQN3I.jpg

[andyvh1959]

Actually, that picture of a knife/fork connecting rod is where the Vulcan and the Harley engines are the MOST similar, and the most different at the same time. In a Harley, both connecting rods share one crank journal on the same centerline. In a Vulcan 1500, 1600 or 1700, both connecting rods share one crank journal, but the cylinders are offset by the width of the connecting rod big end. In a Vulcan big V-twin the cylinders are not in line to each other like they are in the Harley big V-twin.

But the Vulcan and the Harley do not have the same firing order. In fact they can't just because of the difference in V-angle; 45 degrees for the Harley, and 50 or 52 degrees for the Vulcan and that both the Harley and Vulcans share a common crank pin. A Harley fires at 315 and 405 degrees. A 1500/1600 Vulcan fires at 310 and 410 degrees. The Vulcan 1700, at 52 degrees V-angle fires at 308 and 412 degrees.

https://thunderpress.net/editorial/columnists/motorhead-memo-v-twin-vibe-angles/2014/11/15.htm