Topic: CBR Regulator Rectifier on a 750

[jacquesleclochard]

Cleaning up the electronics, and asked my local bike shop for a regulator rectifier combo. They said that a CBR unit might just work on my CB750. I am a dabbling expert when it comes to wiring, so here I am again, asking for help! What would you guys say, would this be a go?

[bluezboy]

 Naaaah, forgot about the combo unit and buy a new rectifier and regulator. I bought mine from Oregon Motorcycle Parts about a month ago and they work great. Besides, if that combo unit goes bad, you lose money replacing the whole unit.

[Jerry Rxman Griffin aka MuthaF'er]

But would the CBR work??!!

There is another thread about the DOHC units going also. These are interesting scenarios. Let's get some serious info/testing on these units and confirm or deny these then report in. Both are plentiful and should be better than stock, not to mention reasonably priced as compared to new aftermarket replacements. May only take a replacement connector to match up.

[jacquesleclochard]

Good, lets. I placed the order, so I will let you know what happens.

[GammaFlat]

Cleaning up the electronics, and asked my local bike shop for a regulator rectifier combo. They said that a CBR unit might just work on my CB750. I am a dabbling expert when it comes to wiring, so here I am again, asking for help! What would you guys say, would this be a go?

In terms of the rectifier, as long as it's wired correctly and it's designed to manage 3 phase, you're probably good.  The voltage regulator... hmm.  PinHead had a great thread going on this topic (regulators) and lots of folks are using the Ford pickup truck version for $13 from Autozone. 

To build your own rectifier, you can do that for < $20 worth of parts (including great connectors) as opposed to trying to get a new one from Honda for your right arm, a couple eye teeth and a few pints of blood. 

[dave500]

if the cbr has a permanant type magnet field it it wont work,these regs more or less just dump excess voltage to ground,youll have no feed voltage for the electro field,the rectifier component will work though.

[jacquesleclochard]

I'm going to hook this up tomorrow - 180 days + after the initial topic start! Gosh, where is the time?
On the scematic side, it should work; the CBR unit only has three yellow wires, and a black and a red.
So there's the alternator, the ground, and the battery.
Mmmm. I'll keep you updated.

[Spanner 1]

Mr. Jacque....... if it only has 3x yellow, a red and a black ( ground )... then it's a rectifier only, no regulation........... Dag !

[dave500]

ive used and am using a permanant magnet type rec/reg unit for just the rectifier side of things,i just use a bosch automotive external regulator.


too easy.

[jacquesleclochard]

Mr. Jacque....... if it only has 3x yellow, a red and a black ( ground )... then it's a rectifier only, no regulation........... Dag !

Yeah, I guess, I KNOW! But I keep telling myself it's possible, because the guy who sold me the part is one of the two official Honda dealers in the town. He claimed it was possible.
The wiring scematic of the CBR unit states it actually is functioning as a regulator rectifier. Here, bottom right:
http://electricwiringdiagram.com/wp-content/uploads/2009/07/wiring-diagram-2008-cbr-1000rr-motorcycles.jpg
I'll give it a go. Maybe it works, and I'll hush myself and the naysayers. If not, well, then I'll see what happens next.

[dave500]

it wont work,that schematic shows no field circuit,it has a permanant type magnetic field,you can hot wire your electro field hoping the excess will all go to earth but i think youll cook somewhere using it on an electro field,(THAT YOUVE HAD TO HOT WIRE)do you even understand how your alternator works?FFS?
Yeah, I guess, I KNOW! But I keep telling myself it's possible, because the guy who sold me the part is one of the two official Honda dealers in the town
who just got a non returnable sale.,you can use the rectifier part of the wiring but you will have to REGULATE the field power,with a regulator.

[jacquesleclochard]

No, Dave, apparantly I don't know how the alternator works.

I'm just learning these bikes on the go, falling down and getting up. Figuring and inventing new things is the fun part.
The engine was easy to learn, the electrics still have lots of things that I don't understand.
Care to point me in a right direction concerning the alternator?

[dave500]

no sweat,,these charging systems have an electro magnetic field,that is basicly switched on and off as the battery needs charging,,it needs a good battery to start with,,when this electro magnetic field is strong the stator feels this as energy and relays it to the rectifier as alternating current,it goes thru the rectifier as ac and comes out as dc and then to the battery,when it gets too much and the battery cant take no more the regulator cuts the power to the electro magnet and the charging stops,untill the battery(which is hooked on electricity)wants more,and so the cycle continues,,,the rec/reg your trying to use comes from a system that uses a permanant magnectic field,,it cant get any stronger,so can therefore deliver only so much,,but if it dose overdose the battery,,the regulator(for want of a better word)it dumps it to the ground and wastes it as heat,the more voltage you apply to the electro magnet type the more you get out of it more or less,so lets cut the voltage when it gets too high,with the permanant magnet type the voltage cant go higher than a little more than whats needed,so its easily wasted to ground,this type of reg wont work with our live fluctuating voltage field magnets.

[jacquesleclochard]

It makes a lot of sense, a fluctuating voltage can only be regulated by feedback. What are the excesses of the electric charge the alternator delivers?
What damage can be done if the excess heat does not find a way out? I take it the fuse blows, wires burn up. It makes sense, yes. I'll take this rectifier/regulator unit back to him and ask him again: is this a wise idea?
The guy said, again, on the phone that is would work. Easy to hook up. You know, I can't imagine that he does not know of the difference between alternators. He saw my oldtimer and knows it as such.
That's the confusing part; the part where my brain conflicts between what you said and what he is supposed to know.

[jacquesleclochard]

So, wait, if I were to replace my alternator with a permanent magnet alternator... one that would deliver a constant voltage, I wouldn't need a battery at all, would I?

[Bodi]

Technically correct but difficult in practice. What PM alternator will fit, and will it have enough output at low RPM (kickstarting) to provide a spark? You will still need a regulator. Extra power is dumped to ground, so there's a horsepower penalty since your engine has to make the power wasted by the regulator.
Many two-strokes of the 70's had magneto ignition and a PM alternater for lighting - the lights flickered badly at idle. I think you will still need a small battery for starting and to ensure spark at idle. Obviously electric start will be deleted.

[dave500]

take it back to him and ask him to describe where the field will be getting its power from via that rec/reg.