Topic: CB500 Simplified Cafe Diagram

[PurduePete]

Hey guys,

I am modifying a 73' CB500 into a cafe racer. Before I get groans, not going to modify any OEM components and will be building a plug and play wiring harness so that I can go back if I ever wanted to.

That being said, I'm struggling a little bit. There are a lot of diagrams out there. Most are pretty helpful but the regulator/rectifier combo unit is making things a little bit complicated for me. Was hoping that someone can help. Already designed my own wiring harness schematic that left out the horn and may end up including turn signals just in case but is mostly complete. Would you guys look and see if you can explain what the black and red from the regulator/rectifier are meant to do. Used a wiring diagram from the link below to help me build the schematic for mine.

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwjopaKYqqzQAhXCeCYKHal9ADIQjRwIBw&url=http%3A%2F%2Fforums.sohc4.net%2Findex.php%3Ftopic%3D120570.0&psig=AFQjCNGr4XENW8Gr_LTjQbF1B1hqPtyAJg&ust=1479353168988262

The white wire to the rectifier is outlined so that should explain the difference. Remember no horn but it should be complete enough to get an opinion on the regulator/rectifier wiring right now. Would like to get it right so that I can post it up and maybe help someone else out in the future. I know a lot of schematics already exist but just don't want to modify anything stock.

[calj737]

The RED wire from your combo Reg/Rec needs to tie to the battery POS terminal. This supplies voltage back to the battery from the stator. The BLACK wire form the Reg/Rec ties into the stock switched 12v service of the bike (usually the key BLACK) to monitor the condition of the battery. This is the "regulator" side of the unit. If the BLACK see that the battery is registering only 11.9v, it allows the Regulator to send voltage back to the battery to restore it full charge. Conversely, if the BLACK sees a "full charge" on the battery, it limits the charge to prevent over-charging.

The issue many people encounter is the BLACK wire tends to have some amount of embedded resistance and therefore measures lower than the battery directly. If that delta is greater than 1.0v you run the risk of over-charging the battery. It is best to insure the Reg/Rec BLACK wire ties into your harness somewhere that reads as close as possible the correct voltage of the battery (as read directly at the battery with a meter). Make sense?

As for your diagram, I don't like it. It is not indicating fuses for the service of the headlight and tail lights. I see a single 20a for the key, thats too high and you have not separated enough circuits. If you blow that 1 fuse, nothing works. As a matter of record, the BLUE wire from your ignition serves coil 1/4 and Yellow serves coil 2/3. And your Stator output harness should be showing a GREEN to connect to your combo Reg/Rec, and the Reg/Rec should have an additional GREEN to chases ground.

Lastly, running a 20a service through your key switch will likely crisp that up pretty quickly. Might want to consider a few relays for the head lights and ignition if you're determined to use a single 20a service. And I hope you've used sufficient gauge wire.

[PurduePete]

Thank you very much for your response. That's the info I was looking for. Let me modify my diagram tonight and put it back up. You are right about the different circuits, should have done that.

[PurduePete]

I updated the diagram. Planning on using 16 ga. wire about everywhere by the way. I modified the fuse from the battery to the switch to 10 amps and added a fuse block. Also added a handlebar switch so that I can put on turn signals if I want to or not. Added the horn too. The fuses in the fuse block will be 5 amp, planning on everything being LED to reduce draw. Going to go pretty small on the battery. There will be room on the fuse block for some spares even. Lets just pretend that the coils are hooked up to a 10 amp fuse... forgot to connect it in the software.

I understand the regulator/rectifier setup now. Didn't know it monitored the battery basically so that explains the black. Thanks for the information and help. Hopefully this one is a bit better.

[calj737]

Looks like you'll be fine. I don't think a separate fuse for the coils is needed, it's certainly not a stock configuration.

Quick question, does your Reg/Rec not have a second GREEN paired up with the RED and BLACK? It's not shown on your diagram, and if it's present on your unit, it's a separate ground.

[Gene]

I learn so much just from reading Cal's posts about electrics.  Not hijacking, just sayin'

Carry on.

[PurduePete]

No, the one that I was looking at getting did not have separate ground paired with it. Assumed that the body of the regulator was the ground on that one. I'll look into it a bit more. Might end up buying a more expensive one just to be sure that I get the right thing. The one from Oregon cycle or 4 into 1 that is recommended.

I really appreciate the helpful post from the gentleman. Helped me understand better and I'll have a better final product because of it too.

[calj737]

The Rick's unit has a separate ground, the Oregon does not and as you say, the body of it is a ground. That requires you to mount it carefully so as to get a good ground. I don't know what bike your building, whether its custom or resto or what, so I asked. Since you're doing a harness from scratch, figured it was custom. So you need to pay special attention to mounting things and grounding things to steel, not painted or powder coated.

The stock bike had ground pins in the controls at the handlebars to insure a good ground. Aftermarkets don't. So if you are using painted bars, be aware of running a ground all the way back to the backbone or somewhere that a good solid contact is made. The stock electric panel didn't supply a ground either. Grounds were run to screws or bolts off the frame and elsewhere. Lastly, the battery ground needs to be pinched between the frame and motor for best results.

Keep us posted!