Author Topic: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????  (Read 370 times)

Offline lazlokovacs

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Maiden voyage after the big rebuild, up the first hill and my mechanic friend behind me toots his horn and I pull over. Holy smokes the alternator is smoking!!!!

Really really hot, like on fire!!!! I had visions of the whole bike going up in flames.

f--- f--- f---- I think were my choice words.

Pulled the cover off asap and very strange inside, the rotor is completely eaten away, like all the aluminium has just been scraped off, like the rotor was too tight in the stator. I certainly didn't notice any tightness when I put them together.... I might have mixed n matched a 2006 stator to 2008 rotor.... But the two rotors measured the same width in any case....

Anyone got a clue?????

Offline pat80flh

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Not a clue, but glad to see you're making progress...
00 Bassa
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Offline nc43bsa

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In the past I have seen where Norton/Triumph/BSA rotors have had similar destructive events.  In their case, the rotor and stator had insufficient clearance, but since they are normally oil-cooled in the primary case, they were a little less dramatic.

In any case, it was strongly recommended that the clearance be verified with a brass feeler gauge when the stator was re-installed.  I remember checking my Mille stator when I re-installed the stator after installing the Valtek tensioner.

<edit> Oh, and it probably is obvious that you'll need a new rotor and stator.
« Last Edit: June 26, 2021, 01:04:31 PM by nc43bsa »
1990 MilleGT

Offline guzzisteve

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WELL, at least it runs. Call Euromoto in CO and get a new one. The whole thing not 1/2.
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Offline lazlokovacs

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weird thing is... I don't really know what caused it...

I'm fairly certain that the ducati rotor/stator combo have no differences in diameters over the years, and it wasn't like we had to force the rotor on to the crank....

The yellow wires leading to the reg are totally undamaged...

Antone brave enough to try a theory?

woodruff key coming loose???


Offline John A

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Stator not seated properly is the only idea Iíve got.
John
MGNOC L-471
It is easier to fool people than it is to convince them that they have been fooled-Mark Twain

Offline guzzisteve

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+1 on that. Only thing I can think of also.
"Pray through Carlo & your bike shall be healed"
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Online Rich A

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Isn't there a key for the shaft? It's a little bugger, maybe it wasn't installed.

Rich A

Offline jacksonracingcomau

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JUST, WOW
Outside of electric fire, I canít get it
Watching for diagnosis, better than telly
It mightíve actually been the very first Guzzi alternator fire ever

Online Wayne Orwig

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Maybe there was a change to the rotor size, but not that I know of.
That is weird.
Scientist have discovered that people will believe anything, if you first say "Scientists have discovered...."

Offline lazlokovacs

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Will have a proper look tomorrow,

in the meantime, my best hypothesis is that the old woodruff key might have been attached to the rotor???

Having said that I believe it was checked at the time of installation...

Maybe the key in the slot just worked it's way loose and got pulled into the rotor by magnetic force?

Will definitely post pics when I can, there is a deep gouge in the ally of the rotor, all the way around, the little ally shavings obviously got VERY hot, no actual flame seen, but plenty of smoke.

I promise you the cable is barely singed, although obviously the solder let go.

Hope the rotor comes off the crank without bother!

 .


Offline Stevex

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Pics?
Steve
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Offline John A

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Will have a proper look tomorrow,

in the meantime, my best hypothesis is that the old woodruff key might have been attached to the rotor???

Having said that I believe it was checked at the time of installation...

Maybe the key in the slot just worked it's way loose and got pulled into the rotor by magnetic force?

Will definitely post pics when I can, there is a deep gouge in the ally of the rotor, all the way around, the little ally shavings obviously got VERY hot, no actual flame seen, but plenty of smoke.




The errant key theory makes sense, it could have moved during installation, itís a strong magnetic attraction there.

I promise you the cable is barely singed, although obviously the solder let go.

Hope the rotor comes off the crank without bother!

 .
John
MGNOC L-471
It is easier to fool people than it is to convince them that they have been fooled-Mark Twain

Offline Don G

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I always check them after install. .006-.008" clearance, check and rotate crank 1/4 turn, check again and repeat....    DonG

Offline lazlokovacs

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update - rotor jumped the woodruff key, yikes.

I have the correct woodruff key on order and luckily a spare alternator rotor combo.

photos to follow


Offline lazlokovacs

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Harper's Moto Guzzi
Harper's Moto Guzzi. Where we still answer the phone, use the highest quality parts, and also do Transmission, rear drive, and carb rebuilds fast. Call us at 816.697.3411 and get your problems resolved.
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Harper's Moto Guzzi
Harper's Moto Guzzi. Where we still answer the phone, use the highest quality parts, and also do Transmission, rear drive, and carb rebuilds fast. Call us at 816.697.3411 and get your problems resolved.
http://www.harpermoto.com
Advertise Here