Alternator Rotor Chip

[cowboyup3371]

While cleaning my bike today, I noticed this chip off the inside/front of the rotor. Any ideas as to what could have caused it and if it will be a problem for me? Should I start looking for a new rotor?

[TheCafeKid]

No idea for sure what may have caused it except perhaps (and I've done this a couple of times) if that retainer that holds back the wires leading to the stator isn't situated just so I've had it rub on the rotor. Usually it makes a pretty good racket that would warn you to figure out what's causing it. I don't know that it would cause such a chip though.

Those mags are pretty fragile. I've made the mistake of smacking the rotor when trying to remove it with even a rubber mallet and they've shattered. Fortunately i had another rotor on hand. Look closely to see if the chip has caused any further fractures in the mag...if not maybe you're ok. If so I'd look for another rotor. The last thing you want is that shattering and pieces of that floating around in your engine, sticking to things made of steel like your crank etc.

[cowboyup3371]

Thanks. I'll look tomorrow.

[JEEPRUSTY]

Unless you know the chip was popped off in a trauma then button the thing up and drive.

It may be nothing more that a simple break caused by heat cycling.

[cowboyup3371]

Thanks Jeep.

I went back outside to feed Lou and grabbed the flashlight to look at the rotor. Although I was unable to take pictures, I saw there are some gouges on the inside of the rotor where I think the stator would sit. I don't remember if that was there from before but I guess it's possible it could have scraped on something. I'll try to post a picture of it tomorrow.

[TheCafeKid]

Unless you know the chip was popped off in a trauma then button the thing up and drive.

It may be nothing more that a simple break caused by heat cycling.

No offense to you Jeep but I would be very hesitant to just "button it up". I know from first hand experience how fragile those things actually are, and generally they don't chip, rather than split, shatter or "spiderweb" like glass.
Kind of like hitting cast iron with a hammer. It seems real solid and strong untill you smack it and it shatters like glass.

My bigger concern would be bits, especially smaller and even tiny ones, making thier way through the engine some how. It may be a pretty remote chance honestly as from what I've been able to discern looking at the pathways of oil flow, for the bits to end up somewhere really bad, as they'd likely get trapped in the sump screen, or simply attach themselves to the outside of the rotor and whatever other steel elements they'd run across prior, but why take that chance if you've already got it open?

That's all I'm saying.

[cowboyup3371]

Is it your suggestion then to go ahead and replace it or should I wait and see? The gouges are 90 degrees away from where that chip sets. What should I consider to make up my mind as I already found a couple on eBay for under $60. I can do that on Friday instead of buying my heated gloves and would rather knock it out now instead of tearing everything back down later.

I'm also worried about any actions I took to cause this. I know i screwed everything back in properly the last time and I don't remember noticeable rattling from there; just from the pipe area. But I have a bad history of screwing things up even when I'm sure I did it right. So I'm getting a little paranoid I think.

[TheCafeKid]

Is it your suggestion then to go ahead and replace it or should I wait and see? The gouges are 90 degrees away from where that chip sets. What should I consider to make up my mind as I already found a couple on eBay for under $60. I can do that on Friday instead of buying my heated gloves and would rather knock it out now instead of tearing everything back down later.

I'm also worried about any actions I took to cause this. I know i screwed everything back in properly the last time and I don't remember noticeable rattling from there; just from the pipe area. But I have a bad history of screwing things up even when I'm sure I did it right. So I'm getting a little paranoid I think.

Well I have no idea if anything you did would have/did cause it. You've been in there before I take it, but do remember seeing it chipped before?

Were it me, as paranoid as *I* can be, and if you ask some of the other members that have been around me long enough they'll tell you that I can be quite when it comes to my motorcycles, I'd replace it just to ease my mind.

However, if you've never removed a rotor before, I'd do some searching and reading, as they don't just come off by removing that bolt or nut. You might even see if Tom Kent or someone near you has the correct rotor puller you could borrow to make the job easier.

[Normk]

If you don't see that magnetic piece adhering to anything in the immediate area, it is most likely an old injury from when someone was in there and dropped the rotor or struck with a tool.

Don't bother about it as have seen lots of examples over the years. The amount of material lost is insignificant and if there are no signs of other cracking, leave it alone. That magnetic material is quite brittle and chips readliy. It's not going to make its way as far as the pump screen in even the most remote possiblity.

If there are signs of gouging it is likely that something else was left in there, dropped into that space and chipped the end of that magnet. Just look for loose objects and ride.

[cowboyup3371]

Okay, as I said last night I felt some additional gouging on the inside about 90 degrees from the chip. Here's what I found today:



That chip was also sitting on the inside of the rotor along the wall below where it came off.


Am I understanding how this rotor works properly - the stator sits fully inside the rotor. Rotor spins around the stator and the electrical charge produced from the magnet is then pushed back through the wiring to the R/R? If that's the case I could understand how the chip got there based on the fact one of the brackets holding the wiring seemed loose although I remember loctiting it down. But how would those gouges be able to get in there unless maybe they are from previous owners and I don't remember seeing it from before.

What kind of rotor puller would I use? Is it one of the standard automobile ones you find at Oreillys? Is it the 2 or 3 prong kind? Or is there a specific motorcycle one?

I'm really hoping this doesn't keep me down too long as I need to get this back to being my daily driver quick

[Nessism]

As long as there aren't any fractures in the magnetic material I'd be inclined to let it go. Maybe degrease the chip area and spoon on a little JB Weld to seal it over? You don't want the material to mound up, just cover the raw area.

At the same time, I'd keep my radar up for a cheap rotor. Should cost more than $25 + shipping.

BTW, to remove the rotor you need a long bolt. The swingarm pivot bolt thread size is the proper size for the larger GS bikes but I'm not sure about a 550.

[Motocrossx23]

Won't this affect the balance of rotation while in motion?

[cowboyup3371]

Would I be out of line if I dropped the oil pan and made sure I didn't have any fragments in there from those chips?

Reading over the clymer's (I'll look through the service manual shortly), I see I need some red loctite for the bolt. Is there anything else I need to remove that rotor?

[tom203]

Me. I'd get another rotor. The magnets are cast into the rotor and you might not see hairline cracks waiting for you at 10k rpm. The magnets will grab anything they can and further unpleasantness might be headed your way. I'll guess you can ebay one under $25- though if you're in a hurry who knows?

[Matchless]

The starter clutch parts have a habit of flying out and getting pulled into that area by the magnets. Your stator may also show some damage.