alternator and rectifier regulator wiring Q

[TailDragger]

I did a fairly exhaustive search and came up with nothing concrete. A project bike I bought came wired but needs an overhaul.

Bike is 1980 1000SP converted to square fin big block and is equipped with a Bosch alternator, FH020AA Regulator Rectifier (R/R), and a M Unit.

I got the bike started before I tore everything apart but as I'm putting things back together, I'm starting to question the way it was originally wired from the alternator to the rectifier regulator and M Unit. The yellow phase wires from the alternator to the R/R are a no brainer and not an issue. The blue and purple DF and Y wires were routed directly to the M Unit's Aux ports which I believe are both 12v out, which doesn't seem correct. The R/R has no input for these wires and I'm going nuts trying to figure out where they're supposed to go. Obviously, I'm a novice at wiring this type of system so any guidance is much appreciated.

By the way, when the bike was running, the lights were all flickering badly.

[berniebee]

The wiring of the purple and blue wires to the M unit is definitely wrong, but more importantly the FH020AA is not designed for a field coil alternator, which is what the stock SP1000 alternator is.

You need a regulator like this one:
https://www.mgcycle.com/index.php?main_page=product_info&cPath=37_161&products_id=1109

You can check back here for help in wiring it.

[Frenchfrog]

Get the adjustable version of that regulator and you are even better off as the voltage can be tweeked to optimum.https://www.mgcycle.com/index.php?main_page=product_info&cPath=37_161&products_id=1110

[Old Jock]

The wiring of the purple and blue wires to the M unit is definitely wrong, but more importantly the FH020AA is not designed for a field coil alternator, which is what the stock SP1000 alternator is.

You need a regulator like this one:
https://www.mgcycle.com/index.php?main_page=product_info&cPath=37_161&products_id=1109

You can check back here for help in wiring it.

Spot On 

The first thing to fix is that Reg/Reg it's a Shindengen (or a Chinese knock off) if it's a Shindengen it's a great Reg/Rec for a permanent magnet generator and is shunt rectifier, pefect for 99.9% of all motorcycle charging systems BUT not the Bosch system, which uses an Electro Magnet to regulate the field and therefore the alternator output.

Check out the charging system for either older BMW airheads or early model Guzzis.

PO may have been using the 12V out on the M-Unit for voltage sensing, which would work (I think), anyway it's irrelevent you need a different RR

[Tom H]

I could be wrong, but doesn't the square fin engines use the large regulator mounted just under the triple clamp? The one listed at MG Cycle I think is for the older round fins?

Would like to know for sure?

Tom

[TailDragger]

Thanks everyone for the valuable feedback. I found the correct rectifier regulator at revival cycle. It’s specifically designed for Guzzis with a Bosch alternator and is also suitable for lithium batteries. https://revivalcycles.com/collections/motorcycle-charging-systems/products/bmw-airhead-and-moto-guzzi-lithium-optimized-reg-rec

[Old Jock]

I could be wrong, but doesn't the square fin engines use the large regulator mounted just under the triple clamp? The one listed at MG Cycle I think is for the older round fins?

Would like to know for sure?

Tom

I could be wrong here too Tom but I think you're referring to the Ducati Energia Reg/Rec.

That was used in later models like the Sport and the Alternator is a single phase permanent magnet.

The square fins like my LM 1000 definately used the Bosch system

John

[Murray]

Have a search for Holden red motor charging system somewhere between 1964 and 1980 should cover it.