L-twin engine vibration. Why?

[Steve G.]

If you want to get picky about it, you can say with accuracy that all internal combustion piston engines vibrate, and that alot [i say most] of the vibration in any piston engine is in fact the explosion of the fuel mixture, not the inherant mechanical design/layout, or percieved lack of balance of the engine. You want an example? Run your Guzzi down the road at 50 mph, trailing throttle. Not much vibration. Now lay the throttle open, and there is a significant rise in vibration. If this engine or any were badly out of balance, it would shake regardless of throttle setting.

I have a multi-cylinder bike [6 banger], and people say'oh it must not vibrate at all. Well, yes it does, if you roll the throttle wide open it sure does. But because the combustion chambers are so small comparitivaly, it's more like a tingle.

As for the argument of transverse vs longitudinal, well, I've been to many bike rallies, bike campouts, bike museums, etc, and the simple words used by the common person [Joe Six Pack if you will], is "in line" describing an engine layout in line with the frame, and "across the frame" describing and engine across the frame. And a Moto Guzzi v-twin is most definitely an 'in-line' engine.

Ciao, Steve G.

[helicopterjim R.I.P.]

Not to pick nits here but I always thought that if the crankshaft was "in line" with the forward-backward axis of the bike then it was called "longitudinal" (like the Guzzi, BMW, Honda ST1100, etc.) and if the crank was perpendicular to the forward-backward axis it was termed "transverse" (Duc, vertical twins, V-twins, every UJM in-line 4, etc.). 

 

Someone chime in with correct definition.

 

Tim

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I have been waiting for Al to jump in here.

[Guest edusinowicz]

Good Morning,

 

The web site referenced earlier is http://pdmec4.mecc.unipd.it/~cos/DINAMOTO/indexmoto.html

 

Go to online papers > Engines> Shaking forces of V-twins. As they say a picture is worth a thousand words. FWIW, I was of the understanding that Moto Guzzi has a transverse V while Ducati and Aprilia have longitudinal V’s. I’m also of the understanding that only the Ducati can be described as an L-twin as was coined by Fabio Taglioni himself.

 

Best to all,

Ed

[Guest Steve_W]

FWIW, I was of the understanding that Moto Guzzi has a transverse V while Ducati and Aprilia have longitudinal V’s.  I’m also of the understanding that only the Ducati can be described as an L-twin as was coined by Fabio Taglioni himself.

Must...Control...Fist...Of...Death... It's the other way. Common misconception based on how the engines look in the frame.

 

Taglioni called the Ducati V-twin an L-twin because it looks like an L in the frame. Both the Guzzi and the Ducati are twins with the cylinders separated at 90 degrees, so architecturally they're the same. They're just mounted differently.

[Guest edusinowicz]

Oh no, not the Fist of Death!

 

Misconception? I'm not so sure. I've read engineering texts where an engine such as a MG v-twin being described as transverse because of the relationship of the cylinder layout to the frame. I've also seen reference to an engine being described as transverse because of the relationship of the crankshaft to the frame.

If one enters 'transverse v-twin' into Mr. Google a lot of references to MG are returned. Yes, I know, I read it on the internet so it must be true.

Perhaps this is one of those counter-clockwise vs. anti-clockwise kind of things.

 

Best,

Ed

 

P.S. I'm glad it was only the Fist of Death and not a 'Dutch rub'.

[Skeeve]

Oh no, not the Fist of Death! 

 

Misconception? I'm not so sure. I've read engineering texts where an engine such as a MG v-twin  being described as transverse because of the relationship of the cylinder layout to the frame. I've also seen reference to an engine being described as transverse because of the relationship of the crankshaft to the frame.

If one enters 'transverse v-twin' into Mr. Google a lot of references to  MG are returned. Yes, I know, I read it on the internet so it must be true. 

Perhaps this is one of those counter-clockwise vs. anti-clockwise kind of things.

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It's dependent upon the crankshaft, actually. As for the "counter-" vs. "anti-" clockwise thing, that's just dialectic variation: they both mean the same thing.

[Lex]

All,

 

Another example of why I shouldn't try to write posts on my lunch hour. My apologies to the smart folks I angered and the gullible folks I mislead. The Guzzi engine is inline, a Ducati is transverse, NOT the other way round.

 

Lex

[Frank]

Hi,

 

Ninety degree V twins do NOT intrinsically have perfect balance BUT they can be 100% balanced by counterweights.

 

To quote P. E Irvings's Motorcycle Engineering:

 

"In 90 degree form, perfect primary balancing is obtained by counterweighting 100% of one piston plus the small-end. The unwanted centrifugal force from this weight at 90 degrees position from No. 1 cylinder exactly cancels out the primary inertia force emanating from No. 2 cylinder and this applies to all positions of both pistons. The secondary forces must, however, be taken into account, because they can be large enough to be serious in a big engine." He goes on to state that these secondary forces (less force but higher frequency) act in the horizontal plane, which on our bike, means they act across the frame, side to side, not front to back.

 

 

The link for the automated engine diagrams is:

 

http://www.mecc.unipd.it/~cos/DINAMOTO/twi...otors/twin.html

 

 

Frank

[antonio carroccio]

The Guzzi engine is inline, a Ducati is transverse

 

.............

[Guest edusinowicz]

Good Morning Folks,

 

First let me say that I’m not trying to stir the pot so to speak, but I am interested educating myself as to the correct definition of transverse vs. longitudinal with respect to motorcycle engines.

Ducati describes their v-twin as longitudinal.

http://www.ducati.com/heritage/anni70/750gt/750gt.jhtml

I mentioned earlier that I was under the impression that the MG v-twin was transverse. Now I will be the first one to tell you that when I pop the hood on my Honda I see a transverse engine. Is there a disparity between automotive and motorcycle nomenclature?

Could someone recommend a motorcycle engineering reference that has a definitive explanation?

 

Yours in confusion,

 

Ed

[twhitaker]

I think the difference in these definitions between the automotive and motorcycle industries has much to do with the quantity of cylinders. From the beginning autos were built with multiple cylinders with the crank and cylinders inline with the vehicle. Along comes the front wheel drive where they place the engine transverse to the car. I think the automotive uses the in line - transverse to describe the orientation of the CRANK.

 

Motorcycles in the beginning were predominantly one or two cylinders and the industry used the terms to describe the orientation of the CYLINDERS. All of your HD, Indian, Henderson, Vincent, Brough, etc were in line engines. The Henderson and Indian 4s were called in line 4s even though the crank was placed perpendicular to the predominant arrangement.

 

When Triumph and others came out with vertical twins I don't think they were called transverse twins but they are. Honda came out with the 750 four and it was called a transverse four.

 

This cylinder arrangement is why I believe our bikes are called transverse twins.

[Admin Jaap]

I wonder why a lot of people are jumping on these definitions? Is a transverse twin better than a longitudinal? If not why bother about it?

[Guest edusinowicz]

Guilty as charged

http://www.wildguzzi.com/discussion/viewto...7a18a89f80ef82a

[helicopterjim R.I.P.]

I think the difference in these definitions between the automotive and motorcycle industries has much to do with the quantity of cylinders. From the beginning autos were built with multiple cylinders with the crank and cylinders inline with the vehicle. Along comes the front wheel drive where they place the engine transverse to the car. I think the automotive uses the in line - transverse to describe the orientation of the CRANK.

 

Motorcycles in the beginning were predominantly one or two cylinders and the industry used the terms to describe the orientation of the CYLINDERS. All of your HD, Indian, Henderson, Vincent, Brough, etc were in line engines. The Henderson and Indian 4s were called in line 4s even though the crank was placed perpendicular to the predominant arrangement.

 

When Triumph and others came out with vertical twins I don't think they were called transverse twins but they are. Honda came out with the 750 four and it was called a transverse four.

 

This cylinder arrangement is why I believe our bikes are called transverse twins.

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Just curious but if the alignment of the cylinders defines whether an engine is longitudinal or transverse then conversely a V4 engine is not a V4 but a "square" engine (in fact there is a bike known as the Ariel 'square four' ). I am hoping to see Laverda's rectangular 6 in California this year, as well as Honda's MotoGP pentagon racer.

 

(Forgive me Al, but I had to say something!)

[helicopterjim R.I.P.]

Guilty as charged

http://www.wildguzzi.com/discussion/viewto...7a18a89f80ef82a

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How many helicopter pilots does it take to change a light bulb?

Two! One to mix the martini's and the other to call the mechanic!

 

What did the helicopter pilot say to his date at midnight?

Enough of talking about helicopters. Let's talk about me now!

 

I could go on but I won't!