Solid State Regulator $14.99

[pamcopete]

This regulator requires you to modify the connections on the brushes of your alternator to work like the brushes on a '80 to '84 model.

1. Got to www.napaonline.com or your local NAPA store.
2. Search for part NAPA MPEVR38SB $14.99
3. Remove the ground connection from the inner brush.
4. Replace the three screws on the brush holder with nylon (not plastic) screws (M4-12)
5. Run a wire with a 7.5A inline fuse from the now isolated brush to a source of +12 volts from the ign switch (brown wire)
6. Install and wire the regulator as shown. The wire connections to the regulator use female bullet terminals.
7. The regulator does not have a ground wire. You must ensure that the case of the regulator is grounded. The battery box, where the stock regulator mounts, floats on its rubber mountings and is not a ground.



In the process of testing this setup for the '80 to '84 models I modified my bike as above and installed the regulator. Works the same as the VR291.

This regulator was used on virtually all Chrysler products from 1970 to 1989. It supplies a regulated ground on the green wire to the rotor brush instead of battery so if the rotor shorts out to ground it will not fry the regulator or blow the main fuse. I like it because it is technology from the same era as my '78 XS650 and it's available everywhere for a very low cost, not because it's a cheap product, but because there are lots of them out there and the auto stores are interested in selling them. Advance offers a one year warranty.

The wire connections to the regulator use female bullet connections, but you should remove the protective plastic from the connections for better contact.
Note: Also available from NAPA as their part number MPEVR38SB for $16.69 or from your local "retired vehicle" yard for $5.

[pamcopete]

Here is a picture of the regulator mounted in the same location as the stock mechanical regulator.



I used two 1 1/2 in. "fender washers", one on the inside and one on the outside of the hole in the battery box to provide a place for a screw on the upper left mounting hole of the regulator. The upper right screw goes in the stock threaded hole for the stock regulator.

I also grounded the battery box because it is not normally grounded.

[bassman56]

Hey Pete,
This is why the smart guys all have 5 stars and I only have 1.
I responded a few days ago to a new member about checking his rectifier because the problem he described was similar to mine. Thought I had my problem fixed. NOT!

The problem is not in the rectifier but in the regulator. All the checks read 0 ohms resistance. I guess the 10 ohm resistor is shot. The battery still doesn't charge and all the connections on the regulator appear to be good. Just no resistance where there should be.

Since Mike's doesn't offer a replacement for the old regulator I was sure that there must be a fix available on the Garage. I'll try this and see what happens.

Thanks for everything, including letting me be cocky and stupid.

the bassman...

[pamcopete]

7808
If there is anything connected to either brush when you check the resistance to ground you will read continuity to ground. Unplug the regulator when you check continuity from the brush to ground and disconnect the black wire from the inner brush.

The black wire that was or is connected to the inner brush is also a ground. You have to remove the black wire and connect a separate wire to the inner brush with an inline fuse to the brown wire. One way to do this is to simply run the wire out of the bottom of the alternator cover, along the frame up to the headlight bowl and put the fuse in the headlight bowl, and connect it to the brown wire from the ignition switch.

[7808]

the reg, was disconnected.

already ran a new wire. i just wanted a lazy way

thanks for the help. should be testing the new reg. shortly


by the way, im impressed, how did you go about figuring out which car regualtor would work good on our bikes, and be cheap and redily available too?

[pamcopete]

7808

Well, you can't do anything electrical without patience, so...get a grip!!

1. Disconnect the green wire at the regulator and measure the voltage coming from the brush. You should see the 12 Volts from the other brush through the rotor winding.

2. Ground the green wire. This will provide full, unregulated current to the rotor.
3. Start the engine and check the battery voltage. You should see a rise in battery voltage as you open the throttle. Don't let the voltage get above 15 Volts.

[7808]

ok found some wierd stuff

with bike turned on

i get no battery voltage at green wire at regulator

i do get batt. voltage at both brushes.

[xsleo]

Ok, Battery voltage runs from the brown wire to one brush, thru the rotor, out the other brush,on the green wire, to the regulator, where the regulator grounds to control the current thru the rotor. This controls the output of the stator. If you are getting power at both brushes but not at the green wire, I would check to see if the green wire is broke.

[7808]

pretty much went through and re wired my bike today and it seems to be working great now. little over 12v at idle and around 15v reved up ;D now to build the radio shack rectifier and this thing should be pretty reliable

power is now going through the brushes like it should.

[pamcopete]

7808

OK. That's great. The voltage is a little high, so do these things:

1. Replace the main fuse with a new one and clean the fuse holder contacts.
2. Measure the voltage drop across the ignition switch between the red and brown wires with the switch on and the headlight on.

The voltage regulator actually regulates the voltage on the brown wire, not the battery itself. If there is a voltage drop across the fuse and/or the ignition switch, then the the alternator will produce a higher voltage to compensate for the drop.

If you measure more than about .3 volts across the ignition switch with the headlight on, then take the switch apart and clean the cheap brass contacts.

BTW...how much did you pay for the regulator and where did you get it? Part number?

[7808]

this bike has mostly all new wiring and switches and fuses, there was not even a headlight connected when i was testing voltage. all the harness battery fuse and ground connections are new/soldered/crimped/clean. new fuse block. ill have to ride it around for a while to make sure its good, its done this before then fried a regulator. i was using a new small 5.4ah sealed lead battery thats about half the size and weight of the stock one, but i dont have the starter connected. and i was only using a headlight no other lights or accesories.

the regulator came from o reilly auto parts and was $13.99(new) it was for a 89 dodge pickup with a 3.9L think it was a half ton or somthing , all the parts stores have there own part number for the same looking regulator.

R29c
vr-125 are the numbers on the "master pro" part box from o'reillys which is a large chain where i live near minneapolis

[7808]

one quik question, the ring terminal on the top left screw on the brushes, i leave that disconnected right? on the screw i ran a new power wire to i mean. i belive it was showing ground so i bent it out of the way.

[pamcopete]

7808

If you are referring to the black wire that was original connected to the brush that now has your new connection to +12, then yes. You might want to put a piece of heat shrink tubing over it so it doesn't migrate over the brush and short out the +12.

[malloy]

will this work for my 1975, my original regualator is looking like hell

[pamcopete]

malloy,

Yes, it will work on your '75. You will have to do the nylon screw mod to the inner brush to remove the ground and wire +12 there instead.