Topic: Old Twin Wiring - Regulator/Rectifier Combo

[uber_franz]

Hey Fellas,

Got an electrical question for the twins guys out there.  Would have posted to hondatwins, but, well, you know...

I'm just wrapping up my SL350 Flattracker project and have wired in a combo reg/rec unit from a CM500 because I've heard the selenium rectifiers are a known weak point in the electrical system.  The problem is that the battery isn't charging.  Voltage at the battery doesn't get above 12.5 at 5000 rpm test.  So I'm wondering if I have the thing wired correctly.  Here's what I got:

Reg/Rec      Alt/Harness

Yellow        Yellow
Yellow        White
Yellow        Pink
Black          Black (Switched Power)
Red/White   Red (Directly to Positive Battery)
Green         Green (Ground)

In addition to the regulator/rectifier mod, I also have a pretty small battery tucked up under the tail section.  It is brand new, and I don't think it is the culprit.

I'm wondering if this is perhaps an issue with not getting power to the field coil?  Or perhaps the alternator is not a three-phase unit?  I don't know, I'm guessing at this point as my electrical skills are lacking.  There was a post on the hondatwins site that addressed this issue, but...  =(

By the way, here's a pic of the project:

[kirkn]

Hey, Franz,

Welcome aboard.  Nice project!

Not sure which bike you used the regulator from.  Don't recall a CM500.  I do recall a Honda CX500 (liquid-cooled V-twin) and a CM400 (air-cooled parallel-twin).

Both those donor bikes used a field coil setup with a three-phase alternator.

Unfortunately, your SL bike doesn't have either of those two things.  It's two separate single phase outputs and it uses a permanent magnet rotor.  Pink wire is a common point (like connected to the bottom leg of a capital letter Y).  White wire is one of the top legs of the capital letter Y.  Yellow is the second top leg of the capital letter Y.  Tie the yellow and the white wires together for maximum charging output (ie, lights-on).  Pink is one of the AC inputs to the rectifier.  White/yellow combined is the other AC input to the rectifier.

I think you're out of luck in terms of using that particular reg/rec but someone else may be able to chime in.

Again,

Welcome aboard!

Kirk

[uber_franz]

Roger that...  Just re-wired with the original regulator and rectifier and the issues seem to be fixed.  Time to go for a ride!!!  =)

Anybody know of a donor regulator/rectifier that will work with the two-coil twins?

Cheers!

[mark]

Oregon Motorcycle Parts has a combo unit for $90 plus freight:http://www.oregonmotorcycleparts.com/VRRPM.html

To the best of my knowledge.... the regulator on these bikes is not as much of an issue as the rectifier usually is. A replacement can be made up from a full-wave bridge and a heat sink:

The heatsink was recycled computer junk topped with a GBPC3504 (35A 400V) bridge, readily available from an electronic supplier:http://www.greatplainselectronics.com/products.asp?cat=18&pg=2

Nice bike, btw.


Happy trails.

[Bodi]

I may be way off but I think the bike has a single phase alternator with two output coils. One is used with lights off to power the ignition (and a bit extra for battery charging), the other is added in with lights on to provide the extra power for them. There's no regulator, the thing is supposed to balance out and just give enough juice for the load. So a three phase rectifier just won't work. There may be some modern regulator that would do the trick but I don't know which - the GL1100 I think used a wasted power regulator that dumped excess voltage... but the 1100 motor had plenty of hp to spare heating up a load resistor. The Lucas system used a zener diode shunting excess voltage to ground too, maybe this approach would work. But if you have stock ignition and lights with roughly the same amperage load as stock, you could do it Honda's way: just switch the extra alternator winding in when the lights are switched on. the stock wiring diagram should show you which colour wire is the "always on" winding and which goes through the headlight switch as the "extra juice" winding.

[tbpmusic]

I may be way off but I think the bike has a single phase alternator with two output coils. One is used with lights off to power the ignition (and a bit extra for battery charging), the other is added in with lights on to provide the extra power for them. There's no regulator, the thing is supposed to balance out and just give enough juice for the load. So a three phase rectifier just won't work. There may be some modern regulator that would do the trick but I don't know which - the GL1100 I think used a wasted power regulator that dumped excess voltage... but the 1100 motor had plenty of hp to spare heating up a load resistor. The Lucas system used a zener diode shunting excess voltage to ground too, maybe this approach would work. But if you have stock ignition and lights with roughly the same amperage load as stock, you could do it Honda's way: just switch the extra alternator winding in when the lights are switched on. the stock wiring diagram should show you which colour wire is the "always on" winding and which goes through the headlight switch as the "extra juice" winding.

Where the main harness ends in the headlight shell, connect the yellow wire with the white/yellow wire (both of them come from the main harness). You've bypassed the handlebar switch, in this context.
Now you're charging full-tilt boogie all the time.

bill2

[uber_franz]

Done and done!  Since I had to replace the controls, I wired the headlight in the always on position (Safety First!).  Then I connected the white and yellow coming out of the alternator coil and sent them directly to the regulator and rectifier.  Figure I need the xtra juice for that headlight.

FYI, there is a Regulator on the bike...  It has a little screw in the end.  Seems like I read somewhere that this can be used to adjust the voltage sent back to the battery.  Any truth to that?  If so, that would be good, cuz I'm hitting about 15.5 V at the battery at 5000 rpm.  Don't want to fry the little thing by overcharging.  It's a small 1.3 Ah Werker AGM cell tucked up under the tail.

Cheers,

Jer

[crazypj]

Hey, Franz,

Welcome aboard.  Nice project!

Not sure which bike you used the regulator from.  Don't recall a CM500.  I do recall a Honda CX500 (liquid-cooled V-twin) and a CM400 (air-cooled parallel-twin).

Both those donor bikes used a field coil setup with a three-phase alternator.

Unfortunately, your SL bike doesn't have either of those two things.  It's two separate single phase outputs and it uses a permanent magnet rotor.  Pink wire is a common point (like connected to the bottom leg of a capital letter Y).  White wire is one of the top legs of the capital letter Y.  Yellow is the second top leg of the capital letter Y.  Tie the yellow and the white wires together for maximum charging output (ie, lights-on).  Pink is one of the AC inputs to the rectifier.  White/yellow combined is the other AC input to the rectifier.

I think you're out of luck in terms of using that particular reg/rec but someone else may be able to chime in.

Again,

Welcome aboard!

Kirk

 Don't know what a CM500 is, probably CX as mentioned?
Neither use a field coil, they are both permanent magnet like the 350.
 your wiring is right, the black wire to a switched live is for the voltage regulator.
Either the stator is shorted/open circuit or the reg/rect is not working.
I used 'late' model CM/CB250/400 reg/rect on just about everything with a PMS system
 What resistance readings are you getting on y/p, etc?
 PJ