Topic: How to install a rectifier/regulator

[Foyil100]

Hi All,

First and foremost I'd like to come clean and admit, I'm a total idiot when it comes to electrical issues.

Now that that's out of the way... I just purchased a regulator/rectifier for my 78' CB750F and was wondering if anyone knew where I could find some pictured instructions on how to install it. It would be a HUGE help!

PS here is a pic of what it looks like:

PPS I used the search function..couldnt find anything

[jdubb1977]

it's pretty much a plug and play setup as long as you bought one specific to your year/model (i just did the same thing).  disconnect the stock regulator & rectifier, and the plug & loose wires on your new unit will match up perfectly.  no guesswork involved (i'm pretty awful at electronics).  the only hiccup, for me at least, is that the mounting holes in the unit don't line up perfectly w/ the brackets on the bike.  you might need to get creative there, or use some cable ties. 

[Foyil100]

Thanks for the heads up just wasn't sure exactly which units to remove (terrible..i know.)

[RickRR]

If you got that exact rectifier you pictured it won't be plug and play . On the 78F there's a third , green ,wire with the black and white .
I read somewhere that there is a way to plug this one ,with only 2 wire , but I don't know how.
Someone ?!

[goldarrow]

Thanks for the heads up just wasn't sure exactly which units to remove (terrible..i know.)

if don't know which unit to remove, then how do you know if you need to replace???

[Foyil100]

Hey Rick,

That's just a generic pic I found on their site, the one I have might have the third plug but I forget, I wont be certain until I get home tonight.

[Foyil100]

Thanks for the heads up just wasn't sure exactly which units to remove (terrible..i know.)

if don't know which unit to remove, then how do you know if you need to replace???

I have a charging issue so I decided now was as good time as ever to replace all my electrical components (good or not...I know, sounds like blasphemy). I'd rather pay the extra $$ to have peace of mind knowing all the components are new. I recently purchased the bike earlier this year and am in the process of an overhaul so the next project is all electrical (just ordered Dyna S, Coils, plugs..etc).

[calj737]

While I applaud your willingness to replace defective components, I'll bet you dollars to donuts that these purchases may not solve your problem.

Electrical is not difficult, though it can be intimidating if you are unfamiliar with it. You need to test and diagnose your electrical system, so that when you install these new components, they work and they don't get damaged by existing faulty electrical connections.


If you'd like to evaluate your existing system, so that you correct or replace the actually damaged component, let us know. Throwing money and parts at a problem is not likely to solve your issues efficiently.

[Foyil100]

Cal, thanks for the input. I agree it may not solve it but at the moment the game plan is to replace everything with newer components for peace of mind.

That being said, what do you think a charging issue could be? I was originally told the rectifier might be the problem so I am starting there. What else do you think? I also may think it's my battery to be honest so I just ordered a new Shorai 8-cell so I can cross that off the list (we'll see when it comes in).

Thanks again

[calj737]

Can you provide some details of what "charging problem" you actually have? I'm not trying to be prickish at all, but some specific information is necessary.

For instance these bikes don't actually produce sufficient charge from the alternator until passing 3,000+rpms to feed the electrical system. Until then it's running on the battery. Have you tested the voltage at the battery? While running? At several rpm levels?

The most typical charging problems are battery and poor connections. A usual suspect is the actual ground wire from the battery. This must connect between the engine case and frame via bare metal in both circumstances. Can you verify that?

If you do want a detailed diagnosis chart, I can happily forward a link to a commonly used and very good troubleshooting link. But you'll need a
Voltmeter to perform the actual tests.

[scottly]

Thanks for the heads up just wasn't sure exactly which units to remove (terrible..i know.)

Here's a pic of the stock units, with the regulator on the left and the rectifier on the right. The green wire that connects to the regulator is a ground, and would not be used with the combination reg/rect picture you posted, as it is already grounded through the green wire in the plug.
 

[Foyil100]

Thanks for the heads up just wasn't sure exactly which units to remove (terrible..i know.)

Here's a pic of the stock units, with the regulator on the left and the rectifier on the right. The green wire that connects to the regulator is a ground, and would not be used with the combination reg/rect picture you posted, as it is already grounded through the green wire in the plug.

This is exactly what I was looking for! Thank you kind sir! 

[Foyil100]

Can you provide some details of what "charging problem" you actually have? I'm not trying to be prickish at all, but some specific information is necessary.

For instance these bikes don't actually produce sufficient charge from the alternator until passing 3,000+rpms to feed the electrical system. Until then it's running on the battery. Have you tested the voltage at the battery? While running? At several rpm levels?

The most typical charging problems are battery and poor connections. A usual suspect is the actual ground wire from the battery. This must connect between the engine case and frame via bare metal in both circumstances. Can you verify that?

If you do want a detailed diagnosis chart, I can happily forward a link to a commonly used and very good troubleshooting link. But you'll need a
Voltmeter to perform the actual tests.

Hey Calj,

You don't sound prickish at all, we're all here to help and I appreciate that . What I mean by charging issue is really I would fully charge my battery, put it in the bike, leave the bike sit for a week or so and when I returned there wasn't enough battery to even kick the bike over. I'm leaning on the battery being bad so I ordered a new Shorai battery (the old one was generic brand..brand new though  ). Someone had told me to try a new rect/reg before hand so I ordered that too.

[calj737]

I have the Shorai also, and really like it. A battery should not go bad sitting for a week. If it does, you either have a bad battery, or a parasitic drain. The Reg/Rec is not involved in the storage capacity of a battery. I still like the more modern Reg/Rec, just because I prefer modern electronics. Theres nothing at all wrong with the stock units, but if you are motivated to replace items, that is one that does get replaced frequently.

BEFORE you replace the Reg/Rec lets sort out your battery issue. The proper test is to fully charge your battery, then allow it to rest, off the charger, for at least 2 hours. Compare the voltage between "fully" charged and "after a rest". There should be no appreciable drop. For a standard lead acid, you will see about 12.4-12.8v. With the Shorai, you will see 13.2, 13.4 and all the way up to 13.8v.

Now for the Reg/Rec: understand its function so you can clearly diagnose any problems in the future. It (the R/R) sits between the battery and the alternator. It measures the state of the charge in the battery while the bike is running, and metes charge from the alternator to the battery. When the battery is depleted, it allows more charge to reach the battery. When the battery is full, to throttles the alternator's output from reaching the battery. Hence, "regulation".

An alternator left "unchecked" by a R/R will over-charge your battery, throwing as much as 15+v at the battery. That will cook your battery instantly. So, once your battery is installed, and verified "good", then install the R/R and verify the following:

Voltage at the following RPMs-
2,000
3,000
4,000
5,000

The voltage read from the battery (meter on + and - terminals) should never exceed 14.8v with a Lithium battery. If you see more voltage than that, your R/R is not properly wired. You should see from 2,000 RPMs voltage around 11.8-12.4, and then climbing with each 1,000 RPMs. This is verification the alternator is functioning. What remains is whether the R/R is properly managing the output, and whether the battery is successfully capturing and storing the voltage. Make sense?

For eliminating electrical problems, step-by-step is really the only way to isolate what is wrong, then correct it. If you change numerous things simultaneously, you will chase your tail for a while.

All of the above is predicated on good, solid ground connections, clean connections between all circuits, and no unusually high resistance in the harness (resistance is produced by corrosion as a by product of poor continuity as an example). If you really want to insure that you are solving your problems, grab a decent multimeter and lets start checking stuff before changing it. It will only take a little while, but will pay huge dividends every mile you wish to drive!

[Foyil100]

Calj - you're my hero for writing that! Thanks mate! I'm going to be picking up a good multimeter this weekend along with some electrical cleaner & grease for all the connections. I'll start with your instructions for testing the battery & R/R; hopefully the case is just that my old battery was defective.  Thanks again! 

[calj737]

And remember to check the battery ground strap to bare metal between engine case and frame. This is more important than you think. If the frame is painted, remove the hangar bracket and scrape the paint or powder coat to bare metal on the bracket and frame, put some dielectric grease in the surface, and reinstall.

[Foyil100]

And remember to check the battery ground strap to bare metal between engine case and frame. This is more important than you think. If the frame is painted, remove the hangar bracket and scrape the paint or powder coat to bare metal on the bracket and frame, put some dielectric grease in the surface, and reinstall.

Good call, I also just ordered some dielectric grease; i'll be sure to refer back to this thread this Saturday when I work on the bike. Thanks again!

[scottly]

I'm going to be picking up a good multimeter this weekend

A cheap Harbor Freight Cen-Tech meter is all you need. I got one because it was free with any purchase, and have found it to be a decent instrument, although not quite as accurate as my expensive meters.
BTW, a bad rectifier can drain a battery over time.