Reg/rec questions - LM

I’m afraid my knowledge of auto electrics is a bit limited, so I thought I’d tap into the collective pool of wisdom on here!
Need to fit a new reg/rec to the Le Mans. I have an unused Electrex which, barring the fuse on the positive lead, looks to have identical wiring to the aftermarket units sold on line (Electroworld, M&P etc).

So, assuming that wires will correspond to the bike, is there anything different with the internal gubbins that would mean that it would not be compatible with my bike? I don’t know if each bike has different requirements electronically or whether the same internals are used in the heat sink, plus variations for different looms


Assuming you have the Bosch alternator with brushes to excite the rotor, then provided the rec/reg has the correct connections (ie it is intended for this type of alternator) it will work.

NOOO the V11 does not use the Bosch it is either the Ducati type one OR the Saprista depending on the year, My V11 Le mans is a 52 plate uses the Doo Kahh tee type one.

My advice would be contact Electrex give them the type/part No and ASK if it is compatible …You may even find the type/model by searching the elecrex site.

If it is compatible just plug and play The replacement ones new are around £69 heck they ask £50 for a 2nd hand one.

If you do plug the new one in make sure the earths are real good and start it test the volts

No ign
Ign on
Engine running tick over
engine at 3000 rpm IF you get an increast at the 3000 rpm it is working …should be around 13.8-14.5 volts

Too low no good too high fuses will blow battery will be damaged if high volts sustained for any long period

You are right of course Ken, I didn’t look too closely at the original post.However, provided the wires all match then you should have no problems.It would be the Ducati alternator, the Saprisa was phased out mid 90s.

You have to wire up a charging light with the Electrex. At least on the T3 / Spada type reg rectifier you do.

OK, I have got the old unit off now, and want to clarify the connections before I launch into altering the wiring.On the Guzzitek wiring diagram, there are 2 reds spliced into one red/greenwhich go into a 30A (F3) fuse to the battery. There is a blue which goes to the charge light, a black/red which I assume is the earth and the 2 yellows to the alternator.On the Electrex, I have a red to the battery (instructions say it doesn’t need to go throught the fuse?), green is the earth, white to the charge light and the 2 yellows.SO, can I just connect the new wiring to the old and not have to modify the loom at all or have I missed something.I’m hoping to complete this on Saturday, so any advice gratefully received.The connections were pretty ropey and corroded when I removed the old reg/recThank you!Just come across a stray socket: I’m assuming it’s for an accessory - wired direct to the battery through a 30A fuse, it’s a 2 pin jobbie with a rubber cap sealing off the end, with a little puddle of water nestling in the bottom. Now that’s not going to help, is it?

Welshguzzi2013-12-05 22:07:41

The Electrex must have a model / type number, can you not Google it or look / ask on the Electrex site to make sure it’s the one intended for the V11

Had various discussions about this. The V11 uses a Ducati unit, and the RR51 I bought for my old bevel drive Duke but never used. General opinion is that it’s compatible, and certainly appears to be OK. I just want to make sure it’s as I described before making any irreversible changes to the loom (you’re talking to an electronics imbecile here!)I’ve tried Electrex but they were a bit unforthcoming

It should just plug in mate take off the old one and check if wires are the same I know the only difference is that some do not have a charge warning light

That’s what I wanted to hear! Gonna get happy with the soldering iron…
Cheers GB

I would suggest you use the existing type connectors to check it all …THEN if you really want to solder them…

I always tend to twist or use a plug to join wiring then check it, on 12v worst you do is blow a fuse… altenators are alot more oomph tho…

I have found it is well worth using vaseline OR even silicone to keep water and dame out of any connections IF you can get hold of the grease that BT use to protect their outdoor connections it is totally brilliant stuffguzzibear2013-12-06 10:35:54

Got it connected via crocodile clips. Without the white connected to the charge light circuit, I get battery and neutral lights on the dash, but as soon as I plug in the white, I blow the headlight fuse.
The only difference as far as I can see is that the white on the new one goes directly through the charge light to the battery, whereas the original takes it from the gen light via the tacco… maybe?
Confused and a bit irritated with my lack of understanding

Suggestions? Not keen on too much butchery of the loom Edit - tried again with new fuse: I suspect that I had not earthed ip properly as I now have battery and Neutral light on, but no Gen, however, the fuse is OK…
Welshguzzi2013-12-07 15:52:27

Well, from what I can see from the wiring diagrams, on the original reg, the blue wire to the generator light puts an earth on until the volts are up to charging level, the 12 volts to the bulb is supplied from the red/black wire from the reg which also supplies the tach.I am using this diagram. I know on the older Saprisa reg, the generator light was powered from the reg and the other side was just earthed.Is there any way you can check if the white wire has volts on it with the ignition on but the engine not running?
Brian UK2013-12-08 09:39:35

Thanks Brian,
Intuitively, the one I have just slots straight in, it’s only the charge light that’s not coming on with the ignition on but engine not running. I would check the bulb but the bolts are seized on the dash!
I’ll put the old one on to check it.

Leave the white wire disconnected, and earth the wire from the dash that it should connect to. Turn on ignition and see if light is on.

Do you know how old the Electrex unit is? The ones up until about 4 years ago didn’t allow for the charging light to be used. I have one on my T3 Cali which charges the bike beautifully but no charge light (well, did, haven’t used it for a while now. The newer ones do allow for a charging light to be used. I’ll agree that Electrex are pretty useless - I also have another unused unit lying around that I was considering using and emailed them politely to ask if they had the wiring diagram for it. Ages to answer and couldn’t help. You’d think they’d keep that stuff on file.

It’s a few years old but the wiring diagram specifically routes the white through the charge light. I had a bit of a barney with Electrex as I had good information after trying to install it on the bevel that it wasn’t any good, but they wouldn’t have it. It was the take it or leave it approach - wouldn’t even look at the wiring diagram I sent to give me a clue as to the way they thought it ought to be connected.

Well then that is a kind of result DO NOT BUY ELECTREX STUFF FOLKS

There are a fair amount of these regulators for sale new from £69 as they are fitted to many other bikes Ducati and other Guzzis as well as other bikes.

I was considering one of these as an upgrade BUT I will look elsewhere guzzibear2013-12-08 20:14:06 Edited to make link work.
Brian UK2013-12-08 22:25:26

That looks like the original wiring on the Guzzi diagram, so should work OK.What I said above about grounding the wire from the warning light which should connect to the white wire is correct.Where they talk of testing the AC part, low output in these alternators is often down to the rotor losing magnetism.