Alternator question

[Thirtyaughtsix]

So I'm walking through the nightmarish hellscape that is the wiring harness, and I think I've come to discover I have an oddball alternator, which would be my luck. Mine is pictured here on the right, the other I pulled from google. From everything I can find I'm supposed to have a blue wire here running up to the Y terminal on my rectifier but it quite simply does not exist in my instance, my guess being that it would plug into the WTF terminal I have circled above, but don't actually have. I also don't even have the Y terminal on my rectifier, further adding to my chagrin.

What would all of this mean? Could I still plug everything in as best I can and hope I'm good? Should I order a whole new harness from Greg Bender? It is worth noting that while on Day 0 the bike was able to start and run, we didn't check to see if any of the lights anywhere worked

[guzzisteve]

Maybe early airhead alt from /5, can't remember if they used Y terminal or not.   Your charge lite work?

[canuck750]

I have had a couple of those style alternators on a few Tonti bikes I have built, Guzzi does not appear to use that terminal where as BMW does, I don't have it hooked up on any of my bikes and I have had no issues.

[Thirtyaughtsix]

Maybe early airhead alt from /5, can't remember if they used Y terminal or not.   Your charge lite work?

No idea, not that far yet

[rbm]

"Charging around the Circuit" Very handy guide that desscribes the electrical circuits on your M-G.

The Y connection (missing on your alternator; present on the Ebay one) would connect to the MP tab on your rectifier.  That connection is like a neutral wire.  You can read about its effects in this web page on Bosch charging systems.  This connection is optional on Bosch rectifiers as well.

[rodekyll]

Guzziology has the write up . .. I'm away from my copy.


Do they  use the Y terminal?  It's been a while; I thought not  The Y is the common lug for the three phase windings.  The other end of the windings are at the 3-blade connector.  Since you're A/C right there I think that stays unconnected.  Someone correct me please?

This part I'm on firmer ground --
What you're looking at is an early and late type.  The early type is not showing the Y terminal.  If you measure the ID of the stator and the OD of the rotors involved you'll see a difference of a couple mm or so -- I can't remember the details -- but one rotor is like 73mm and the other is 75mm, with correspondingly different stators.  The early one is the smaller and puts out marginal power.  I'm sure someone can correct this too, but I think it's like 18amps.  It is more associated with early BMW boxers than the Guzzi.  If they really were ever on the guzzi as oem it was for a very short time.  Avoid if possible, and be sure to not mix pairs.  The bigger one is still anemic at 22amps or thereabouts (220w rings a bell).

[Antietam Classic Cycle]

I have had a couple of those style alternators on a few Tonti bikes I have built, Guzzi does not appear to use that terminal where as BMW does, I don't have it hooked up on any of my bikes and I have had no issues.

This ^^^. Early Tonti Bosch alternators didn't have the Y terminal.

[Thirtyaughtsix]

This ^^^. Early Tonti Bosch alternators didn't have the Y terminal.

Ok, I'm glad up not up the river then. Everything seems to line up obviously enough so I'll hope it all works when it's done.

The write up is in fact in guzziology, can confirm now that I have it in front of me