Crankshaft Balance - Does Rotor Contribute?

[GSChoppa]

I've been fooling around with ideas to slim down the left side of my GS750. I'm thinking about binning the electric leg, trimming some excess material off the cases and installing a late model belt driven ZX or Katana alternator. I know it's a waste of time...but I can't seem to leave well enough alone (plus the idea of a 8000 RPM belt ready to slice off fingers intrigues me).

My question is: I've noticed on every early GS rotor I've seen, there are various amounts of material that has been methodically drilled away along the exterior. I assume this is for balancing purposes. My question is if the material is removed to balance just the rotor - or the entire crankshaft assembly? Rotor replacement (or removal) would certainly be an undertaking not to be taken lightly if crank balancing depended on a matched rotor. Has anyone replaced a rotor and noticed any difference? For that matter, has anyone even removed a rotor and then installed the same one (surely at least slightly askew from original position) and noticed a difference?

I've got my brackets pretty much designed...and I've got an alternator that just fits in the available space...and I think I can get an oil seal to keep the crank from weeping oil...I just need to find out if I can remove the rotor and keep the balance in order. Let me know what everyone thinks...

Thanks,
GSChoppa

[bwringer]

Yes, you are certifiably nuts. :shock:

But you knew that already...

Anyway, since they're not keyed, and the manuals make absolutely no mention of reinstalling rotors in the same position, I can't imagine that the rotor has anything to do with crank balance.

Thousands of GS mechanics have re-installed thousands of rotors willy-nilly without ever indexing them, so I think of all the things to worry about or that could go wrong on this project, you can safely forget about this particular issue.

Is there any way you could use an actual chainsaw chain instead of the belt? I mean, if you're going to endanger some fingers, why mess around? The curious should be punished.

[tone]

Have looked into this before when removing the "rotor" & running a total loss system for racing

it has nothing to do with crank balance & the drillings are there purely to balance the rotor itself IE-: if its in balance which it will be it will have no effect on crank balance the only way to make it affect the crank is to put it out of balance by drilling more holes or welding up the ones there which would be a daft thing to do

as a bonus removing it will make the motor rev slightly faster but some of this will be ofset by the drag of the belt

hope that makes sense to you :-D

[walt]

the rotor only adds a degree of flywheel effect not balance.

[GSChoppa]

As Always...Thanks!

Thanks everyone...

I kinda figured that without a keyway there probably was no way the rotor could be involved in balance...

I was just a little concerned because one of the rotors in the garage must have 30 lightening marks on it. That seemed a bit excessive for just balancing the rotor itself...

Again...Many thanks to all

GSChoppa