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tubarney · March 21st, 2013, 09:55 PM

Here's what they are going to do with your balance factor.

There is no way to keep the factory balance factor if you lighten the crankshaft without taking the same amount of weight off the rods/pistons. Or a percentage of that weight. This where is BF comes in.

Exactly what they confirmed by saying that.

What they are going to do is lighten it. Then balance it to a factor that will stop the vibrations between those revs ranges because there no way to balance it back to factory without making it the same weight again.

It turns out I'm not getting it knife edge as it will put the crank out by a lot and the only way to get it back to factory balance factor is to fill it with mallory until it becomes the same weight again.

Which is pointless and expensive. Plus knife-edging is only beneficial if your crank sits in oil. Which ours does not.

Basically, there balance machine works by giving them a plot of the forces between 0 and 15k revs. They will balance it to a BF that keeps the forces(vibrations) to a min in the selected rev range. You can't stop these vibrations no matter how well it is balanced. Just make them happen in a certain rev range.

This is also why they said it was a no no on the removal of the balance shaft. You would need to experiment in the real world to find a balance factor that would stop it from happening in the selected rev range.. They can't calculate this with their machine. They would have the information for common/expensive race bikes (GSXR1000) but not our little ninja.

Also, you might have trouble finding someone who can fit the crankshaft onto their balance machine. The journals are not wide enough.

Anyone with a Serdi balance machine that uses nylon v-blocks will not be able to balance the crankshaft. Unless they have run into this problem before and have customs lying around.

Not to mention. The first d***head that balanced it did not calculate the Factory Balance factor!!! So make sure they do this.

Anyway, I hope these vibrations you experience below 7k aren't too serious because some can prevent you from holding on the handle bars.

March 21st, 2013, 09:55 PM	#32
tubarney ninjette.org sage Name: Brad Location: Sydney Join Date: Mar 2012 Motorcycle(s): Ninja 250r 2010 SE Posts: 573	Here's what they are going to do with your balance factor. There is no way to keep the factory balance factor if you lighten the crankshaft without taking the same amount of weight off the rods/pistons. Or a percentage of that weight. This where is BF comes in. Exactly what they confirmed by saying that. What they are going to do is lighten it. Then balance it to a factor that will stop the vibrations between those revs ranges because there no way to balance it back to factory without making it the same weight again. It turns out I'm not getting it knife edge as it will put the crank out by a lot and the only way to get it back to factory balance factor is to fill it with mallory until it becomes the same weight again. Which is pointless and expensive. Plus knife-edging is only beneficial if your crank sits in oil. Which ours does not. Basically, there balance machine works by giving them a plot of the forces between 0 and 15k revs. They will balance it to a BF that keeps the forces(vibrations) to a min in the selected rev range. You can't stop these vibrations no matter how well it is balanced. Just make them happen in a certain rev range. This is also why they said it was a no no on the removal of the balance shaft. You would need to experiment in the real world to find a balance factor that would stop it from happening in the selected rev range.. They can't calculate this with their machine. They would have the information for common/expensive race bikes (GSXR1000) but not our little ninja. Also, you might have trouble finding someone who can fit the crankshaft onto their balance machine. The journals are not wide enough. Anyone with a Serdi balance machine that uses nylon v-blocks will not be able to balance the crankshaft. Unless they have run into this problem before and have customs lying around. Not to mention. The first d***head that balanced it did not calculate the Factory Balance factor!!! So make sure they do this. Anyway, I hope these vibrations you experience below 7k aren't too serious because some can prevent you from holding on the handle bars.