Wildgoose Chase Moto Guzzi

General Category => General Discussion => Topic started by: lazlokovacs on June 26, 2021, 11:14:27 AM

Title: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: lazlokovacs on June 26, 2021, 11:14:27 AM
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?????
Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: pat80flh on June 26, 2021, 12:31:45 PM
Not a clue, but glad to see you're making progress...
Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: nc43bsa on June 26, 2021, 01:00:11 PM
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.
Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: guzzisteve on June 26, 2021, 01:15:48 PM
WELL, at least it runs. Call Euromoto in CO and get a new one. The whole thing not 1/2.
Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: lazlokovacs on June 26, 2021, 05:08:59 PM
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???

Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: John A on June 26, 2021, 09:38:18 PM
Stator not seated properly is the only idea Iíve got.
Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: guzzisteve on June 26, 2021, 09:43:21 PM
+1 on that. Only thing I can think of also.
Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: Rich A on June 26, 2021, 10:00:47 PM
Isn't there a key for the shaft? It's a little bugger, maybe it wasn't installed.

Rich A
Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: jacksonracingcomau on June 27, 2021, 06:04:03 AM
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
Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: Wayne Orwig on June 27, 2021, 06:55:34 AM
Maybe there was a change to the rotor size, but not that I know of.
That is weird.
Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: lazlokovacs on June 27, 2021, 06:58:39 AM
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!

 .

Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: Stevex on June 27, 2021, 10:52:22 AM
Pics?
Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: John A on June 27, 2021, 11:42:01 AM
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!

 .
Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: Don G on June 28, 2021, 09:10:40 AM
I always check them after install. .006-.008" clearance, check and rotate crank 1/4 turn, check again and repeat....    DonG
Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: lazlokovacs on June 28, 2021, 10:58:37 AM
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

Title: Re: Got the cali running again and.... Burnt/scorched ducati alternator rotor?????
Post by: lazlokovacs on June 28, 2021, 11:00:46 AM
(https://i.ibb.co/C8Xwnvf/bty.jpg) (https://ibb.co/C8Xwnvf)

(https://i.ibb.co/HKBqMk7/bty.jpg) (https://ibb.co/HKBqMk7)

(https://i.ibb.co/1Zf7gWC/bty.jpg) (https://ibb.co/1Zf7gWC)