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Old 04-19-2010, 09:24 PM   #31
Infracaninophile
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Steverino:

Not sure which way you may go with a new rotor or upgrading. But if you end up with the stock rotor or the Motorrad, go ahead and buy the $5 rotor removal bolt. That funny looking bolt that you just stick in your tool roll. If you end up with an Enduralast I don't think you need one.

I have one on both bikes.

T.
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Old 04-19-2010, 09:33 PM   #32
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In case you haven't heard...

I've only owned 2 airheads in the last 5 years, I've toasted 3 rotors! The first was an original in my '70 75/5, the second was a remanufactured one in my ST, and the third was a 450 watt one from Rick. I have rotoritis!!! There ain't no telling when they're going to go.
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Old 04-19-2010, 09:44 PM   #33
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It would be interesting to know what accessory equipment is being used on bikes that have failed and those that have not.

Is there a correlation or just the luck of the draw. In a case like that of hardwaregrrl I can't help wounder if there is something shorting out or overloading the system.
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Old 04-20-2010, 02:36 AM   #34
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Quote:
Originally Posted by RecycledRS
It would be interesting to know what accessory equipment is being used on bikes that have failed and those that have not.

Is there a correlation or just the luck of the draw. In a case like that of hardwaregrrl I can't help wounder if there is something shorting out or overloading the system.
Electrically speaking, one could overload the stator windings but not the rotor ... there are about 4 A going in most of the time (= 13.6 V/3.2 Ohm), even if you replace the voltage regulator by a short circuit.

The "killer" seems to be mechanical stress, since most rotors seem to fail by an open circuit near the point where the winding is attached to the sliprings (I have yet to see a failed airhead alternator rotor that had a short circuit!). Clever "re-winders" have grasped that idea and are manufacturing rotors with more slack and/or better wiring.

This being said, my GS ist at its 3rd alternator rotor in 20 years now. #1 at 61 Mm (this one was defective and replaced under warranty at 68 Mm), #2 at 104 Mm, now at about 165 Mm ... and a spare is ready in the basement
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Old 04-20-2010, 05:07 AM   #35
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Quote:
Originally Posted by Steverino
Mine was the rotor. Luckily some very nice Texans helped and one even had a spare air head motor in the garage to borrow a rotor from. So I lost 18 hours and got home with no more problems.

Also, there was no neglect on this bike. Every connection was spotlessly clean and protected with dielectric grease.

Roll of the dice rotor failure. Although I do ride ALL my bikes hard.
I'll wager the next time you light out on a 4000 mile trip your well-maintained bike will carry a spare rotor.

It is how most of us learn. I had a rotor failure on a trip too. I was lucky and it failed sometime in the first 450 miles. I was able to get to Dusty Miller's BMW in Tallahassee FL where they quick charged the battery for 90 minutes and disconnected lighting save for a brake light. I got on the interstate and ride straight home 175 miles at 85 mph in order to beat the sunset.
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Old 04-20-2010, 09:11 AM   #36
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[QUOTE]
Quote:
Originally Posted by Joerg
Electrically speaking, one could overload the stator windings but not the rotor ... there are about 4 A going in most of the time (= 13.6 V/3.2 Ohm), even if you replace the voltage regulator by a short circuit.

The "killer" seems to be mechanical stress, since most rotors seem to fail by an open circuit near the point where the winding is attached to the sliprings (I have yet to see a failed airhead alternator rotor that had a short circuit!). Clever "re-winders" have grasped that idea and are manufacturing rotors with more slack and/or better wiring.
Your point regarding mechanical stress is a good one however since the stator and rotor are magnetically linked, any additional load on the stator will will be transmitted to the rotor resulting additional mechanical stress (your point), heat and induced AC frequencies from the stator. The fact that the rotor is DC supplied does not mean that the stators AC influence via Counter Electromotive Force (EMF) are not felt in the rotor. If we were to look at the rotor current using an oscilloscope I suspect there would be substantial AC influence. The power in the stator comes from the rotor.
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Old 04-20-2010, 09:19 AM   #37
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Hi,
Quote:
Originally Posted by RecycledRS
If we were to look at the rotor current using an oscilloscope I suspect there would be substantial AC influence.
I actually did this a few years ago ... quite a gorgeous sight on the scope.

Yes of course there is AC ... not only due to the magnetic interaction you mentioned, but also since the rotor current is actually not smooth DC but pulsed DC (... which makes it, by definition, AC ), due to the alternator regulator cutting in (or should we better say "cutting out" )
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Old 04-20-2010, 10:08 AM   #38
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I guess we agree that the energy produced by the stator must come through the rotor and as such as the bikes electrical load increases so does the electrical/mechanical load increase on the rotor.

Good point that the regulators switching adds additional stress on the rotor circuit windings. Again I suspect there are also substantial harmonics induced from the stator into the rotor. Not a simple DC circuit as first appears.

Practically what does this mean to the airhead owner? Your point, not much as there is little he/she can do to mitigate the effects on rotor life. Bill.
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Old 04-20-2010, 12:21 PM   #39
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Quote:
Originally Posted by RecycledRS
It would be interesting to know what accessory equipment is being used on bikes that have failed and those that have not.

Is there a correlation or just the luck of the draw. In a case like that of hardwaregrrl I can't help wounder if there is something shorting out or overloading the system.
All three times, not much. The first was the original rotor, so no harm no foul there. The second, was a rotor that had about 3 years on it, not abused, the bike only had heated grips and they were not on. The third was a brand new(6months) 450watt rotor, had only my driving lights on at the time. First my brand new Odyssey went, then the rotor about 500 miles down the road?? I'm a freak....
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Old 04-20-2010, 03:19 PM   #40
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Quote:
Originally Posted by RecycledRS
It would be interesting to know what accessory equipment is being used on bikes that have failed and those that have not.

Is there a correlation or just the luck of the draw. In a case like that of hardwaregrrl I can't help wounder if there is something shorting out or overloading the system.

I can tell you that more often than not I'm running zero additional electrics on my r90.

Though, I do like to spin the motor fast.
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Old 04-20-2010, 03:33 PM   #41
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Quote:
Originally Posted by hardwaregrrl
All three times, not much. The first was the original rotor, so no harm no foul there. The second, was a rotor that had about 3 years on it, not abused, the bike only had heated grips and they were not on. The third was a brand new(6months) 450watt rotor, had only my driving lights on at the time. First my brand new Odyssey went, then the rotor about 500 miles down the road?? I'm a freak....
The question is, are you spinning your ST up to redline frequently? Mine failed after I did that a few times....
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your bike is suitably dirty. Well done.
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Old 04-21-2010, 01:57 PM   #42
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For me it's been 12 yrs and 4 airhead bikes. I've lost 1 rotor and 2 diode boards in that time. I always carry these two spares on a long trip. I've added extra grounds for the diode board and make certain my connections are clean. I've currently got a MotoElektric rotor on my bike and an Omega diode board. Seems to me the better heat sink design on the diode board makes sense.

On my 2nd diode board failure, I was riding in Utah with a friend and it was Sunday. We had about 300 miles left to get home so I disconnected the headlight and then we'd stop about every hour and swap batteries. It was a PITA but it got me home. My battery would slowly drain down just running the ignition system but after an hour it still had enough juice to start my buddy's bike. I'd put his fully charged battery in my bike and let his bike put a full charge on my battery. Back and forth a few times did the trick. We got the battery swap down to about a 5 minute procedure.
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Old 04-21-2010, 06:19 PM   #43
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Quote:
Originally Posted by SOLO LOBO
The question is, are you spinning your ST up to redline frequently? Mine failed after I did that a few times....
Ha, I ride like a grandma But seriously, no red-lining before failure!
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Old 04-22-2010, 09:19 AM   #44
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Quote:
Originally Posted by hardwaregrrl
Ha, I ride like a grandma But seriously, no red-lining before failure!
Your rotor consuption could just be luck of the draw, but....... after three failures one has to be a little concerned that something else maybe the root cause.

Have you tested the electrical load (amperage) of the system while running and when any accessories are added one by one? This may tell you if there is an unusally high draw for a particular component and over loading the system.

Also, since the voltage regulator controls power to the rotor it may be worth considering changing this out as a preventative measure (the unit is relatively inexpensive).
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Old 04-22-2010, 10:45 AM   #45
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Quote:
Originally Posted by RecycledRS
Your rotor consuption could just be luck of the draw, but....... after three failures one has to be a little concerned that something else maybe the root cause.

Have you tested the electrical load (amperage) of the system while running and when any accessories are added one by one? This may tell you if there is an unusally high draw for a particular component and over loading the system.

Also, since the voltage regulator controls power to the rotor it may be worth considering changing this out as a preventative measure (the unit is relatively inexpensive).
Trust me, everything is right with the electrical. It has a brand new Omega 450. I have checked the load several times and I have a volt meter that I watch religiously. I'm just saying, they ain't bulletproof!
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