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Discussion Starter · #1 · (Edited)
Just curious if all 90 degree v-twins are going to fire at 270 and 450 crank degrees? Or, are there other configurations for the 90 degree? Or....do have this totally screwed up?
 

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Yeah. Firing pulses alternate between 270 and 450 degrees apart on a 90 degree V-twin (L-twin) with both connecting rods on the same crankpin. There are V-Twins with offset crankpins but I don't know of any 90 degree ones. Any existing would be an exception.
 

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Discussion Starter · #5 ·
Yeah. Firing pulses alternate between 270 and 450 degrees apart on a 90 degree V-twin (L-twin) with both connecting rods on the same crankpin. There are V-Twins with offset crankpins but I don't know of any 90 degree ones. Any existing would be an exception.
That's what I thought. Really, I've been debating with a friend as to why Ducati's sound so freaking amazing. I wanted to eliminate the possibility of it being just a firing order thing. Since it's not...it comes down to the desmo valve setup. Since they are actively forced back shut, that would allow for significantly more overlap (if one wanted or could and still meet emission requirements) and also duration at full open (since a spring wont' be closing them.....they could stay at nearly full open until the last nano second).

Bottom line- Ducs sound amazing, and like nothing else. Why?
 

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That's what I thought. Really, I've been debating with a friend as to why Ducati's sound so freaking amazing. I wanted to eliminate the possibility of it being just a firing order thing. Since it's not...it comes down to the desmo valve setup. Since they are actively forced back shut, that would allow for significantly more overlap (if one wanted or could and still meet emission requirements) and also duration at full open (since a spring wont' be closing them.....they could stay at nearly full open until the last nano second).

Bottom line- Ducs sound amazing, and like nothing else. Why?

Not sure why they sound so fabulous, but they certainly do to me as well. In THEORY ONLY, the desmo design could have an unlimited RPM redline since the valves are forced closed vs relying on springs. The slight downside is that the engines are so mechanically noisey....especially at idle. Is that because of the desmo design?
 

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Way back when Italy could NOT get quality spring wire that would last at high RPM and Lift..... so they got stuck with desmodroneicks

It has NO real world advantage over springs and is inferior to pneumatics
 

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so mechanically noisey....especially at idle.
That's the dry clutch. I don't think the new wet ones are as noisy.
Ducati does have a distinctive sound quality. Not so much out of the box but with non stock pipes. Maybe it has to do with the soul of the bike built to run and not go for a putt.
 

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Not sure why they sound so fabulous, but they certainly do to me as well. In THEORY ONLY, the desmo design could have an unlimited RPM redline since the valves are forced closed vs relying on springs. The slight downside is that the engines are so mechanically noisey....especially at idle. Is that because of the desmo design?
unlimited rpm ? desmos still have pistons reversing direction and stretching rods if they go too fast



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This video may give you some clues.

The Ducati Sound - YouTube

and

New Page 0

Each cylinder of a four-cycle engine experiences the power stroke that creates a “boom” once every other full rotation of its crankshaft. On a traditional parallel twin the pistons typically rise and fall together and the power strokes alternate between cylinders. Thus the ‘booms’ sound evenly spaced and, well, boring. “Boom, boom, boom, boom, boom.”

But a Ducati is different. Because its cylinders are laid out in that fore/aft ninety-degree “L” pattern the “booms” come in a delightfully complex syncopated pattern separated by alternating ninety and two hundred and seventy-degree crankshaft rotations. The ear of course doesn’t care about this engineering, but it does rejoice in the musical sound. “Boom-BOOM. Boom-BOOM. Boom-BOOM!”
Ok same as a DL1000 motor...

Not so in a Ducati. Instead of relying on brutal spring pressure to force the valves to keep in step, the Ducati Desmo system, like a skilled ballroom dancer, guides each valve through its intricate dance with the gentle touch of embracing arms. Since the engine is set to be in perfect tolerances when it is fully warm, a cool Desmo engine has a unique start-up “clatter” whose refrain slowly fades away as the engine warms. To the motorcycle aficionado this is pure music.
:new_shitsmiley:

This guy spends too much time reading wine labels I think..

On a Japanese bike that would be translated as "This sounds like a bucket of bolts until it warms up" but to a person who paid insane money for their bike "this is pure music".

This design, like many found on a Ducati, came out of the Company’s racing program. And its actual purpose is more connected to the efficient transfer of power than to the musical qualities it possesses. None-the-less, a Ducati’s dry clutch is an important part of its sound. One that excites and (sometimes) frightens the uninitiated who ask, “Should it sound like this?” Once they learn that the answer is "Yes" many Ducati owners modify their bikes with the addition of a slotted clutch cover so that they can hear every note of this melodious song.
Translated to a mere Suzuki this would be called Chudder and the answer to "Is it supposed to sound like this" is not believed. However anyone who pays insane money for their bike really wants to believe it is OK and is easily convinced. They will be trading it in ona new one when the next model comes out after only doing 2500 miles in the garage anyway so they will never find out if it is a problem.

There is another voice, too, that serenades a Ducati rider, and it is one that is rarely enjoyed by a mere onlooker. This is the baritone voice of the bike’s air intake system.

This part of The Song emanates from under the gas tank where the airbox and air-filter reside. Created by the deep breath the bike takes before each power stroke, it has been compared to the sound of "an angry woodpecker trying to escape from under the gas tank." In sound it is not unlike a snare drum. And, with its perfect synchronization to the beat of the bike's exhaust, it is a pleasing and important part of The Song of the Ducati.
Translated to a DL1000 that means that Suzuki should put more holes in the Air Box.

Put each of these four sounds together – the cannon-like cylinders firing, the valve-train's start-up clatter, the tambourine-like jingling and jangling of the clutch, and the intake’s snare drum-like beat – and you have the ultimate motor music: The Song of the Ducati.
On a mere Suzuki that translates to "That sounds like a pice of crap mate. What's wrong with it?"

So there you go..

I think you should just put a set of REMUS exhaust pipes on your bike, 3 Inch headers, drill a bunch of holes in the Air Box and drain the oil. You would be pretty much there. If you could find a noisy clutch, that would be the icing on the cake.

Just remember to add the oil back in before you leave your mates place.
 

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Duc sound

due to 2 valves per cylinder on most bikes and more valve overlap than spring valves?
 

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unlimited rpm ? desmos still have pistons reversing direction and stretching rods if they go too fast

That's why I highlighted..."in THEORY ONLY." I knew someone was going to challenge that so you take the prize. Congrats.
 

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Because the Italians CARE about stuff like that and the Japanese don't much.

Pete
Exactly. Ducati spend so much more on the styling and getting the heart to make the decision to purchase. No different with the sound. They must play with exhaust configuration no end while not forgetting the induction noise can play a large part in overall sound. Looks to me as if they keep each exhaust pipe separate. Clue might also be in not much of a link pipe between the two as we see on many. All part of the emotions.

Desmodronic valve system they use is more compact and economical because it runs without valve springs.

No springs adding height to the cylinder heads keeps engine length and so wheelbase down. A 90 degree V has to fit the length of the front cylinder between the back of the front wheel and the swing arm pivot. Gearbox also has to go in this same dimension as you can't stack the shafts because thats taken by the rear cylinder and leaves no room for the sizeable diameter of the clutch.

No rows of springs in the cylinder heads to compress and release in addition to the valves weights which saps engine power output. Leaves more to propel you fwd or saves fuel for the same power output.

Otherwise very close to the same valve timing, bore, stroke and firing interval as our Suzukis. So whats to stop the VStrom (or an Sv) sounding like a Ducati if you had the resources to reconfigure the plumbing both into and out of the heads? Probably nothing at all. Not that we want any of their mechanical noise of course.
 
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