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Discussion Starter #1
The other night I got to take my buddies Ducati Monster 1K for a spin. When I first sat on it I almost sh*t myself because it felt like it was half the weight of my RR is.

He seemed to think it was because the V-twin engine. Are all V-twins inherently lighter? If they are then sign me up!
 

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No. My RC is significanly heavier than the CBR1000RR brother.

It is narrower. THis could lead to believe it is lighter. If he runs higher air pressure than you, that will give the feeling as well. But V-twin has nothing to do with weight.
 

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Don't forget that the twin cylinders are aligned lengthwise within the chasis, which means that the rotational mass of engine doesn't create a gyro effect that'll fight against the bike turning left and right--that's why many twin engines claim to be more flickable than their i4 counterparts.
 

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Discussion Starter #7
It must have just been this bike then. It felt like I was sitting on a BMX it was so light.
 

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It is most probably because it is narrower. Twins are heavier usually for a given engine size because they have beefier pieces to handle the bigger pistons. The part about the rotational mass above isn't quite right, the cylinders would have to be aligned 180 degrees from each other, most twins are not this way. The Monster is not.

This is a pretty good article if you're interested--

http://www.cycleworld.com/index.cfm?siteaction=OnlineUpdate&id=46

If you want a lightweight twin to play with SV650s are cheap and easy to find.
 

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Here is some other stuff I cut&pasted from I forgot where to post in a similar discussion on another board:

"Torque characteristics aren’t inherent, but the product of design. “Twins are torquey, fours are peaky,” is the common belief. And though often true, it’s due more to design decisions made by the manufacturer than to inherent, mystical properties of engines, as conventional wisdom holds.

Power output and power delivery characteristics are determined by a host of variables specified by the designer. In addition to the number and size of its cylinders, intake and exhaust tract dimensions, carburetion, valve sizes, and camshaft timing all affect an engine’s personality. Engine design isn’t a one-dimensional problem, and predicting engine behavior is a lot more complicated than counting cylinders.


“Torquey” vs. “Peaky”
Peak torque and peak horsepower are often the only bits of information we hear about an engine’s performance, but they tell us very little about the subjective feeling of torquiness a motor exhibits on the road. While the peak value tells us how much torque is produced at one RPM, the character of torquiness refers to the more complex phenomenon of rolling on the throttle anywhere in the rev range and being rewarded with a steady and prodigious pull all the way to redline. To predict the subjective feeling of torquiness, look instead at the range of RPM over which the engine puts out at least 90% of its peak. The wider the 90% band, and the lower it extends in the rev range, the torquier the motor will feel.

Horsepower is simply torque in pound-feet measured at a certain RPM, multiplied by that RPM and divided by 5252. So maximizing peak power requires both high RPM and good torque at high RPM. That kind of optimization results in a peaky character, with low torque output at low RPM, rising to a maximum at high RPM.

Counterexamples
Two examples illustrate how engine characteristics can differ from the usual expectations. Fours are peaky? Not the Honda Magna. According to Motorcycle Consumer News dyno tests, the Honda’s 750cc V-4 makes 46.5 lb-ft of torque at 7500 RPM but puts out at least 90% of that value, nearly 42 lb-ft, all the way from 3000 to 9500, 65% of the total rev range. Whack it open anywhere and it pulls hard and steadily to redline.

Twins are torquey? Though the Ducati 748 V-twin generates an abundant 50.3 lb-ft of torque, it doesn’t reach that peak until 8500 RPM. Its 90% band is from 6000 to 10,000, only 40% of the total rev range, and on the bottom end - below 5500 RPM - torque is less than 40 lb-ft. Until the tach hits 6000, the Magna’s torque output exceeds that of the Duc. Comparing a $13,000, 450-lb sport bike to a $8000, 550-lb cruiser is lopsided at best, but when rolling on from 3000 RPM with these two bikes, the four is the torquey one and the twin the peaky one.

Design Advantages and Limitations of Twins and Fours
The inherent advantage of a four over a twin - given displacement, bore/stroke ratio, and other technology - is its ability to rev. A four has smaller, lighter reciprocating components (pistons and rods) with less distance to cover per revolution, enabling it to turn higher RPM without exceeding the capacity of the crankshaft and main bearings to keep everything in one piece. In addition, geometry makes it possible to fit a four with greater total valve area and, thus, the ability to inhale and exhale at a rate proportional to its higher revs. To exploit these advantages, the engineer must provide big carburetors, big ports, and long-duration, high-overlap camshafts. The downside of that sort of optimization is less-than-ideal performance at low RPM. When a four is tuned for maximum power output, and, not coincidentally, best quarter-mile times, it will inevitably be peaky.

Because a twin can’t rev as high as a four, other factors equal, tuning for sky-high revs isn’t an option. But its disadvantage on the top end turns out to be an advantage at the bottom end, since an engine that isn’t optimized for high revs can perform better at lower revs. That’s the fundamental difference that leads to the belief that twins are torquier than fours.

But that’s not the end of the story. Other factors, after all, may not be equal, and even if they are, the engineer still has plenty of latitude to create the kind of performance he wants. Just because a four may ultimately be able to attain high RPM doesn’t mean the designer has to make use of that capability. And just because a twin can have a gutty bottom end doesn’t mean it will tuned that way.

In fact, the range of variation over which the designer has control is much greater than the difference between the ultimate capabilities of twins and fours, as the comparison between the Magna and the 748 illustrates. When designing the Magna, Honda ignored the high-revving capability of the short-stroke V-4 and built it to exhibit a flat torque curve accessible at low RPM, with power peaking at a modest 9000. On the other hand, Ducati had just one thing in mind for the 748: horsepower. Since maximum power requires both RPM and torque at high RPM, they biased the torque curve toward the top end, and built an engine that achieves peak power at a heady 11,000 RPM, just 1000 less than the peak of the 4-cylinder Suzuki GSX-R750.

It Depends on what You Like
With the variety of powerplants available today, a rider has a wider selection than ever before. Those who like the pavement-ripping thrust of Big Torque can get 70, 80, or even 90 lb-ft in either a twin or a four (or even a six). Those who prefer an intoxicating rush of peak power approaching a five-digit redline have the same choice (less the six). There’s more to choosing a motorcycle that makes your kind of power than counting cylinders, so take some time to look at the dyno charts and read the road tests, and don’t jump to conclusions about engine performance."




Also:

"I4 are cheaper to manufacture than a V4, and probably pretty competive with a V-twin despite the increase pistons and valves. I4s have a single casting for the head and cylinders. A 90 degree V-twin bike will always have problems getting the engine far enough forward to get enough weight on the front wheel. I4, or narrower V angles will result in a better balanced bike.

I4's have pretty good natural balance. But the power pulses don't seem to work very well at the ultimate edge of performance. That is one big change to the Yanaha MotoGP bike this season. They've changed the crank and firing order so it is more like a V-twin, with two quick bangs (two cyclinders each time), and then a big pause until the next power strokes. This was done at Michelin's request, supposedly because the big space gives the tire more time to recover traction, and this makes the bike more rideable at the limit. Rossi is enjoying the benefits of this change that it appears was in the works before his decision.

Twins typically need more flywheel weight than an I4, because the power pulses are farther apart, unless you have a weird crank like Yamaha has gone to. The gyroscopic effect of the heavier flywheel can make a racing bike hard to turn-in at higher RPM. A lot of the Ducati riders in WSB will up-shift before a trun, just to get the engine RPM down so they can flick it in easier.

The only twin cylinder engine layout that has perfect natural balance is the boxer ( not boxster , that's a car!) design, and most practical incarnations of that end up with a rocking couple because the cylinders are offset. A 90 degree V-twin can have perfect primary balance with crankshaft weights added, but it they will have a secondary imbalance that would require a counterbalancer shaft for perfect balance.

http://pdmec4.mecc.unipd.it/~cos/DI...otors/twin.html"
 

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The higher, wider handlebar also adds to the light feeling. It give more leverage so less force is required. Look at any AMA superbike from 1986 or earlier and you'll see they got rid of the clip ons and used wider handlebars to make it easier to turn.
 

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Aeteocles said:
Don't forget that the twin cylinders are aligned lengthwise within the chasis, which means that the rotational mass of engine doesn't create a gyro effect that'll fight against the bike turning left and right--that's why many twin engines claim to be more flickable than their i4 counterparts.
Gyroscopic forces come from the crank which is in the same direction, the location of the pistons doesn't have an effect on those forces. The motocyze I believe is the first bike to eliminate this, with a newly designed engine.
 

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Aeteocles said:
Don't forget that the twin cylinders are aligned lengthwise within the chasis, which means that the rotational mass of engine doesn't create a gyro effect that'll fight against the bike turning left and right--that's why many twin engines claim to be more flickable than their i4 counterparts.
The polar moment which is what would make a bike feel lighter while straddling it in a parking lot is likely very similar between the monster and the rr due to their weights (fuel tank, frame, engine, etc.) being similar distances from the ground. So it all comes down to what others have said in that the handlebars are higher on the monster and therefore you will have a greater mechanical advantage over that polar moment.
Like Hessogood said, the Motocycsz C1 should be amazing on a track if they can make enough power so that it can take advantage of it's theoretical supremacy in acceleration, braking and handling. I hope to see clips of it next weekend.
 
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