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

[ubernomad]

Originally Posted by 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.

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]

Originally Posted by blowndodge

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]

Originally Posted by 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.

There's been a three cylinder too: http://www.motorcyclecruiser.com/mak...ple-feuling-w3

[macmac]

Originally Posted by ponch

There's been a three cylinder too: http://www.motorcyclecruiser.com/mak...ple-feuling-w3

That's cool...

[Jllm02199]

Originally Posted by ubernomad

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]

Originally Posted by 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.

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]

Originally Posted by 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.

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]

Originally Posted by Jllm02199

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:
2nd, piped Harley XR1200:
3rd, Harley XR1000 two carbs:


Now, compare that 3rd one with a VN1600:

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/27261...idson-lawsuit/
https://www.thedrive.com/article/113...ing-too-harley
https://auto.howstuffworks.com/question325.htm
https://www.amazon.com/Harley-Davids.../dp/B01L7X2XE4


This should cover most everything....

[Brock]

The reason for harley sound https://www.cycleworld.com/story/blo...-confidential/