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ratherberiding
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Discussion Starter · #1 ·
I read somewhere on here that someone wanted to put a 10r engine in a 6r chassis so he could have the power of a liter, but the handling of a 600. Someone said it would x itself out because the rotating mass of the liter engine makes turn in slower. Now, the Buell twin i rode this weekend turned in so quickly and i wondered if it had to do with the V-twin

So yesterday i accellerated to 50, pulled in the clutch and started weaving heavily. It seemed to turn in so much more quickly. Is it in my mind? Is any of this true? Do lower rpms affect turn in? I don't even know why i care, jus something that popped in my head
 

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Absolutely, the rate at which it rotates definately has an affect. Thats why our bikes are more stable at higher speeds, the wheels are rotating faster making the bike want to stay upright. The same thing goes for the engine.

Thats why liter bikes will never be as flickable as a 600 even if the overall weight is the same, you have more mass rotating. Putting a liter engine in a 600 frame isn't going to solve the problem, you may save a few pounds by having the frame smaller (and weaker) but the shit that matters (the rotating parts) are going to be the same (unless you can make the internals lighter).

As far as lower rpm's making it more flickable, you bring up an interesting idea. You could purposely run in too high a gear to make the bike more flickable. But then you wouldn't have the power on tap when it's time to accelerate out of the turn. Plus the wheels are still rotating at that given speed regardless of the rpm's, and I think that they have a bigger affect.

If you want your bike to be more flickable, get some lighter wheels, aluminum, magnesium or carbon fiber. I hear they make a big difference. The mag wheels are on my wish list, very expensive though.
 

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Well lets put this into respective...

600CC has almost half the capacity of the liter so , if you add the extra strength and size of components of the liter bikes, you are adding at least 30% more rotational mass less gyroscopic effect..

As for the twins...less rotations of the crank..even a POS Buell..
But the bigthing with the buell is the chassis..
If only they put in a real quality V-twin i would buy one...How about a SV1000 motor in that bike, can you say best streetbike EVER!
 

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ratherberiding
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Discussion Starter · #5 ·
cool info guys....so my friend is all about the magnesium wheels...so you're saying this will make his bike noticably more flickable?
 

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Dam right the mag wheels will make the bike handle totally different, when i put on my magnesium wheels it turns in quicker, acclerate quicker, and stops quicker, the reduction of rotating mass is very very noticable.
 

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99% of the gyroscopic effects put on our bikes are from the wheels. not the motor. the reason a 600 bike is more flickable than a lieter, is #1: there is less weight, and since there is less weight, #2: i am going to go out on a brance and say that they might have a lower center of gravity, (i might be wrong on #2but i dont know for sure). as far as gyroscopic properties in the morot, you have to remember that yes the crankshaft is a little bigger in a lieter than a 600, bot most of the differance is going to be in the cylinder. ( bigger bore and stroke). When talking about the gyroscopic principals, in this case what you are refering to is gyroscopic procession.

Gyroscopic procession - when a force is applied to a spining object, the maximum effect is aprox. 90 degree later in the plane of rotation.

this applies to the wheels, and rotors, because you are attempting to change the dirrection of of the spinning plane, and my nature a gyroscope does not want to the direction of the plane changed. in a motor, the pistons are not trying to change the direction of the crankshaft, or its plane of rotation. all they do it provide the energy necessary to keep the crank spinning, and since the cylinders are angleled at 90 degree to the cranks plane of rotation, the provide no change of direction for that plane of rotation. there are some forces that act in the motor, but none that are going to affect your riding. the reason you wheels are affected by gyroscopic procession, it that when you turn, your are attempting to move the plane of rotation. i could go in to the phisice behind counter steering here, but i dont feel like it. we will save that for another day.

as far as you being able to corner faster at a low RPM rather than a higher RPM, may all be in your head. the throttle is easier to control at a lower rpm. (it is less touchy) also at a lower RPM you are not having to worry about when to shift. since your throttle is smoother at a lower RPM, and you are not having to worry about shifting, you are paying more attention to the turn, body posision, and the road. you are not worried, or distracted by shifting, or a jerky throttle. so you have more confidence, and better form, there for you are able to take the corner at a higher speed.
 

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This makes me think of when I was really little and played with a gyroscope! It's quite easier to push around when it's slow, and very stable when spinning insanely fast!
 

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Originally posted by helo-pilot
99% of the gyroscopic effects put on our bikes are from the wheels. not the motor. the reason a 600 bike is more flickable than a lieter, is #1: there is less weight, and since there is less weight, #2: i am going to go out on a brance and say that they might have a lower center of gravity, (i might be wrong on #2but i dont know for sure). as far as gyroscopic properties in the morot, you have to remember that yes the crankshaft is a little bigger in a lieter than a 600, bot most of the differance is going to be in the cylinder. ( bigger bore and stroke). When talking about the gyroscopic principals, in this case what you are refering to is gyroscopic procession.

Gyroscopic procession - when a force is applied to a spining object, the maximum effect is aprox. 90 degree later in the plane of rotation.

this applies to the wheels, and rotors, because you are attempting to change the dirrection of of the spinning plane, and my nature a gyroscope does not want to the direction of the plane changed. in a motor, the pistons are not trying to change the direction of the crankshaft, or its plane of rotation. all they do it provide the energy necessary to keep the crank spinning, and since the cylinders are angleled at 90 degree to the cranks plane of rotation, the provide no change of direction for that plane of rotation. there are some forces that act in the motor, but none that are going to affect your riding. the reason you wheels are affected by gyroscopic procession, it that when you turn, your are attempting to move the plane of rotation. i could go in to the phisice behind counter steering here, but i dont feel like it. we will save that for another day...
[:++1]

I really couldn't have stated it better...maybe 7-8yrs ago and countless bad decisions(sp) ago...too many cobwebs.
 

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This is all interesting info. Having owned the heavier zx6e, with its more commuter friendly ergonomic, and now owning the zx9r with its slightly more race ergonomics but still more weight and longer wheel base, I would love to try comparing a SS 600 to a SS 1000 as far as handling goes. I was never aware of all this momentum being carried on by the mass and all that is being discussed here. I always thought that the new liter bikes should be damn near as flickable as the new ss 600 because they are all light and of such precise design. Grand it the 190 rear on the liter bikes wont turn in as fast, but I wasn't aware there was such a difference in flickability. After riding my 9r for a while I was swearing that I would never go back down to a 600 ss, but since i love the twisties and the 600s appear to be so much better in the twisties, I might have to reconsider that though. I do love the new 600rr that is coming out in 07.


Heres one of the questions I have been thinking about.

Do the engines in 600's not last as long as the engines in 1000's because of all the extra stress being done by all the higher rpms?



I love the fact that I can be at 5k rpm at 80 mph on my 9r, but on a 600 from what I remember your at around 7k to 8k rpm. In the twisties I can be at around 9=10k rpm tops while the 600 would be above 10 the entire time.


I really love the look of that new 600rr, and I hear they are bullet proof bikes. I love my 9r and will never sell it, but if I run itno some more money I am getting that 600rr next year and then I will be able to get used to it and make a comparo to my 9r.
 

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Originally posted by rockstar84


Heres one of the questions I have been thinking about.

Do the engines in 600's not last as long as the engines in 1000's because of all the extra stress being done by all the higher rpms?
Maybe, but not necessarily, your forgetting about the stress caused by the extra mass of a 1000. Force= mass x acceleration. You can increase one and decrease the other and have the same force, theoretically anyway.

Also, engines that rev high usually have a shorter stroke. The pistons go up and down a shorter distance meaning they can complete the cycle faster. So it's not a real fair comparison, they are moving faster but not in the same way.

But I guess there are certain parts that are basically the same between the two and would be stressed more from a high reving engine, the valves for instance. But again, engineers have to take this into account and design these parts with lighter/stronger materials to handle the higher revs. If the engineer is forced to go with a different material to handle the higher revs, say titanium over steel or something like that, it could be that the engine will last even longer because it has better materials.

Bottom line is, I don't know which laster longer. But you can't just categorically say higher revs = less durability unless your comparing apples to apples.
 

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ratherberiding
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Discussion Starter · #13 ·
i think some of you guys might be related to Bill Nye the science guy.....good info guys...I keep soaking in and will consider it truth when I get confirmation. KawiForums rocks!
 

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Originally posted by helo-pilot
in a motor, the pistons are not trying to change the direction of the crankshaft, or its plane of rotation.
Is the bike leaning over not changing the plane of rotation of the crankshaft/flywheel/clutch/tranny shafts, just like turning a wheel changes its plane of rotation (albeit on a different axis?)
 

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Originally posted by BrandonM7



Is the bike leaning over not changing the plane of rotation of the crankshaft/flywheel/clutch/tranny shafts, just like turning a wheel changes its plane of rotation (albeit on a different axis?)
well you are correct, but because the motor is solid mounted in the frame, it acts differant. take a bicycle wheel for example. take it out of the frame, and then spin it as fast as you can. than ballance one side of the axel on your finger. what happens is kind of hard to explain, but trust me it works. then take the same bicycle wheel, and spin it once again, then grab the axel on both side, and try and turn it left or right. see what happens.

what you have to remember is that in both the 600 motor and the 1000 motor, the parts are not that much differant. what makes the displacement differance is the bore and stroke, not so much theh crank size.
 

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Originally posted by helo-pilot

well you are correct, but because the motor is solid mounted in the frame, it acts differant. take a bicycle wheel for example. take it out of the frame, and then spin it as fast as you can. than ballance one side of the axel on your finger. what happens is kind of hard to explain, but trust me it works. then take the same bicycle wheel, and spin it once again, then grab the axel on both side, and try and turn it left or right. see what happens.
I think I remember that demonstration - if you hold it up by one side, it turns in a circle on its own around the axis of its plane of rotation. Held by both sides, it just stays put spinning away, and is quite difficult (relatively speaking) to turn on other axes. I honestly can't remember why, but I do remember me being the student chosen to hold it, and I remember falling off of a stool as a result -- my professor got quite a kick out of demonstrations of physics that led to pain for his students :D

Let me make clear my intention here - I'm not trying to prove you wrong, I want you to prove what you're saying is right. I believe that you know this stuff, because if you're a helicopter pilot you obviously have to have a pretty clear understanding of gyroscopes, otherwise you'd probably be dead. I just want to understand it.

what you have to remember is that in both the 600 motor and the 1000 motor, the parts are not that much differant. what makes the displacement differance is the bore and stroke, not so much theh crank size.
I was honestly thinking more in terms of v-twin vs. I4, as there is a dramatic difference in crank length there - although weight is more important in this case, and I really don't know how much of a difference there is between those. But in regards to 600 vs 1000, you're right, the bore and stroke differ, the length doesn't differ much at all. BUT, a longer stroke is accomplished by longer throws on the crank. Not only does that move the rotation circle out to a larger diameter, it also has to increase weight -- you can't make something longer and of the same strength without making it heavier, unless you change materials. Add to that, they have to channel ~175Hp through that crank to the ground, vs the ~125Hp of a 600 - once again, more weight would be required, unless one was way overbuilt or one underbuilt. I know in regards to car cranks, a small block and big block crank are in the same ballpark on length, but a big block crank is a SHITLOAD heavier. Probably not twice as heavy, but on up there. The heavier the rotating thing is, the less it's gonna like turning.

I wish we could send this to mythbusters, where they could remove all variables and tell us just how much difference it makes. Or if someone would make two completely identical bikes, one using a sleeved block and short-throw crank for small displacement, one using an open block and long-throw crank for large displacement. But they don't. Closest thing is the GSX-R 600 and 750, and people do say the 750 is lazier to turn in -- but they have a wider rear tire, so that's just enough to screw up that comparison.

Damn, you have me really wanting to know the answer now. Mainly because I've read so many people speak of it when talking about the flickability of v-twins, and I want to know if they're talking out of their ass or not. I can think of a strong argument for both sides, but I don't have the means to test either. I may have to wander over and chat with a physics professor tomorrow (I work at a college.) But even then I don't know the weights and dimensions of different cranks/wheels/flywheels/trannies/etc, so even then it would be pure theory and law, which we already have too much of [:p]

I guess the main thing we need to know is the weight of the engine's rotating assembly relative to its overall weight, for both sizes, and the weight of the rotating parts of the drivetrain (wheels/tires/chain/blah,) then we could certainly dig up some formulas to see how much effect each has. We could basically eyeball it at least to see a percentage difference between bike displacements.

Anybody know where to find those types of weights? I sure as hell ain't ordering each piece to read the shipping label [B)]
 

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I was honestly thinking more in terms of v-twin vs. I4, as there is a dramatic difference in crank length there - although weight is more important in this case, and I really don't know how much of a difference there is between those
i still think weight would be more of a factor here. i coule be wrong, but i think that any gyrocopic phenomena by the motor would be mostly canceled by the motor being hard mounted in the frame, unable to exert a negative force. (unlike the wheel which can be freely pivoted around the "neck" axis). ask whild you are at the college to see if i am wrong, i would also like to konw. but as i stated earlier, i think most people would be better in the corner at a lower rpm due to being able to have better throttle control since the throttle is not as responsive "jerky", so that would make them smoother, and they would be able to concentrate more on the turn and proper body position(spelling). and i think that would make the bike seem easier to conrtol and more flickable.
 

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Originally posted by helo-pilot



i still think weight would be more of a factor here. i coule be wrong, but i think that any gyrocopic phenomena by the motor would be mostly canceled by the motor being hard mounted in the frame, unable to exert a negative force. (unlike the wheel which can be freely pivoted around the "neck" axis). ask whild you are at the college to see if i am wrong, i would also like to konw. but as i stated earlier, i think most people would be better in the corner at a lower rpm due to being able to have better throttle control since the throttle is not as responsive "jerky", so that would make them smoother, and they would be able to concentrate more on the turn and proper body position(spelling). and i think that would make the bike seem easier to conrtol and more flickable.
I'm not seeing why it is different for the engine because of the "hard mount" your talking about, maybe I'm just confused. I'm educated just enough to be dangerous, but I'm no expert.

I do agree that the wheels are the major factor though, which I believe is due to the greater radius. The moment of inertia of an object is proportional to the radius squared if I remember right. The engine is rotating and should have a gyro affect, but the radius is less so maybe you don't feel it as much.

Being in a higher gear makes throttle response less jerky and therefore cornering is easier, but thats not what we are talking about here. We are talking about initial turn in and changing direction quickly, not the actual cornering or behaviour of the bike once it's leaned over.

I guess I'll have to pull out my old physics books from college and study this stuff a little more. I like this thread, it has got me thinking.
 

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This is a great thread, and it has got me thinking as well, so here are my thoughts...

On the same bike, I think lower rpms could make turn in easier for the reason that there is less torque and hp being made at the wheel in that rpm range. Therefore, the bike most likely has less weight distributed to the rear and the front forks are less extended then they would be under harder acceleration. Therefore the rake angle would be less than when the bike is pitched back under acceleration and it would turn in much more quickly, precisely what happened when you pulled the clutch in and started weaving. You had no forward drive, and were being slightly slowed by the tire rolling on the road, affecting the weight distribution.

However, you could be at higher rpm just maintaining speed and keeping the weight optimally distributed with good throttle control, and probably turn in almost as fast as you did with the clutch in.

Conversely, if you try to turn in with the front forks compressed from heavy braking - you would most likely turn in way too fast to control and crash. PLEASE DONT TRY THIS!


I do agree with what has been said about the gyroscopic effect of the engine parts, but I beleive that how the weight is distributed front-to-back on the suspension will have a much bigger effect on turn in than will the effect of spinning engine parts. After all, the wheels are the biggest gyroscope to be overcome, and the suspension will greatly affect how efficiently the wheels can carry the weight of the bike into and through the turn.
 
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