Universal Rectifier Regulator


Been Around the Block

I was hoping to get some feedback from the forum on what they used to replace the old R/R on all the project bikes that roll through the forum.

It is for 1984-85 Yamaha FJ600 and I need to purchase a universal Rectifier/Regulator. I am planning on using a Ballistic 8 cell evo 2 battery and a stock CDI unit.

Any help or tips would be awesome! Thanks guys!


There are 2 types of regulators/rectifiers.

One for permanent magnet alternator, one for field excited alternators. They are NOT interchangable.

The permanent magnet type alternator can be 3 phase or 1 phase. You can use one of the three phases on a single phase alternator, but on the three phase alternator, you need the 3 phase regulator.

I do not know which alternator the FJ600 has, but it has one of those three....


Been Around the Block
I don't have a stock R/R to compare to unfortunately...

I have a digital service manual at home and I can check to see what type of alternator it uses. I am looking at Rick's R/R for now. It reports that it is a plug and play fit to my bike.


Went on Bike Bandit parts, for 1985 FJ600, alternator has brushes. So you have a field excited alternator...Ricks is a safe bet, oregon motorcycle has them too...


To be clear, there are 3 phase permanent magnet alternators, as well as 3 phase excited field alternators. There are excited field alternators without brushes (My NH750 is such), but if the alternator uses brushes, it is definitely an excited field alternator.

A 3 phase regulator for a permanent magnet type alternator will not work on a 3 phase excited field alternator. The rotor on the excited field does not have permanent magnets. The regulator varies the current through the rotor winding to vary the magnetic strength so as to control the output of the alternator to match the load.

On a permanent magnet alternator, the output from the alternator is proportional to the RPM. The output is always as much as the alternator can make at a given RPM. The regulator then either shorts the excess current to ground, or on some, electronically restricting the flow out of the alternator......A much different process then the excited field.


Over 1,000 Posts
Ahhh - I sit corrected. I got confused because the XJ's and smaller FJ's have external reg/rec's as opposed to the FJ1100 which has the reg/rec inside the AC generator (like a car).

Here's another question - if we're talking permanent magnet systems can you run 2 of the small reg/recs in parallel to increase their life / reduce the stress on them?

Like these ones:


Just trying to think a bit outside the box because if it's possible, then I'd rather pay $25 or so and nerd with a bit of wiring than fork out $150 plus for a "real" one.


The PM alternators have a max output. If you are using lights and ignition, you are using up some of the current....I doubt if the regulator ever needs to ground out more than 7 or 8 amps....They ground the AC side too, not the DC side....

So I don't believe a second RR would really provide measurable improvement over a 15 or 20 amp rated RR.

Unless you are at max RPM's all the time, you are not really generating excess current all that much.....The newer RR provide a better regulated voltage level than the old ones, but even the old ones lasted quite a long time....

I believe failures have more to do with component build quality then excess current....

MY CB360 is 130 Watt rated, which at 14.0 volts is about 9 amps max...Headlights are 4 amps, the ignition in the 2-3 amp range, charging the battery is in the 2 amp range. So there really isn't a lot of regulation going on....On my regulator, anything elow 14.1 volts is not regulated. Only the rectifier is working.

The problem with 2 rectifiers, is that unless they are identical in the forward resistance, the lower resistance rectifier is still doing most of the work....

If you are worried about R/R failure, just carry a spare.....

For most rides, since I have the OEM sized battery, and most of my rides are fairly short, I have enough reserve capacity, that if the RR failed, I have enough battery, especially if I turn off the headlight, to ride home on the bike.


Over 1,000 Posts
Thanks for the response. I guess the motivating factor in this instance is the cost.

The bike in question is a VL1500 and the reg/rec's aren't cheap:


Hence my questioning the use of smaller ones....

The other ? is about the stator - can a faulty reg/rec damage a stator? Or can using the 2 smaller ones possibly damage it? Currently it's output is in spec (80+ v at 5K rpm).

Just curious if I might be doing more harm than good in the long run...

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