Topic: DOHC rectifier/regulator works in our SOHC cb750!!?

[Industrial Cafe]

could it be true? this guy did it.
http://cgi.ebay.com/ebaymotors/cb750-cb-750-custom-cafe-bobber-old-school_W0QQitemZ160330537680QQcmdZViewItemQQptZUS_motorcycles?hash=item160330537680&_trksid=p4506.c0.m245&_trkparms=65%3A2|39%3A1|240%3A1318
here's a quote from the auction-
"Battery box located under rear hump, uses motocross battery.  Converted to solid state regulator rectifier (off any dohc 750 or 900 works).  The old electronics are very big and ugly."

If this is true, I'm gonna do it!
they're about 50 bucks on feebay


its tiny and it replaces this and this

   Why buy specialty made regulators and rectifiers?

My question is, Who here knows what wires go where... or are the colors the same?

[kghost]

Long wires (yellow) are the rectifier.

[Industrial Cafe]

ok, and the others are colored, so i would just attach accordingly?

[mystic_1]

The search engine is your friend:

http://forums.sohc4.net/index.php?topic=48275.0


Also, here's a pic courtesy of www.hondachopper.com, and another one that I don't remember where I got it from.

cheers
mystic_1

[Industrial Cafe]

holy crap! thats the guy thats sellin his bike!!!

sorry guys, I'd search but I'm sick and my brain isn't working properly... and sometimes at night, I hallucinate from the high fever!!! yaaay

[Industrial Cafe]

awesome- problem solved, thanks mystic!

[Ogri]

So, would any 12V Honda Reg/Rec with that wiring colour coding work ? I'm seeing lots of units for CX500s and Superdreams but few for DOHC 750/900s.
 Or is the amp rating of the battery and the donor bike's alternator output relevant factors ?

[Spanner 1]

I don't like it , and here's why !!!
The separate rectifier and regulator as stock on these bikes are different in this way.....
The reg. has 3 'speeds'....Full-on, Half-on and Off. and cycles between the 3 options depending on the state of charge of the battery. This allows the alternator and field coil to ' rest' for periods during operation. The 'solid state' reg./ rect. allows the charging system to be connected at varying rates all the time......seems to me more stress on the alternator.........and the later bikes have differently wound/ designed alternators....but it will work on any SOHC.

[bryanj]

The CX and  superdrem wont work as they do not have an "Excited" rotor and the generator is regulated by dumping excess current to earth using a zener circuit a bit like the 12 volt triumphs and nortons.

As to not having a rest period the electronic reg is better for the battery and the field coil is rated continuous so it SHOULD be OK

(Not To Be Quoted!!!!)

[Ogri]

Thanks Bryan, I understand now - had no idea Superdreams & CXs used Zener type circuits, interesting!

[bryanj]

I THINK its a Zener type, never took one apart to be sure Workshop book just sez its "Integrated" and shows 9 diodes , 'Wing uses same type of generator as well

[Ira]

Topping this old thread for some help, possibly?

I started using a DOHC reg/rec on my SOHC 750 about a year ago, and it didn't work out well.  It did at first, but not as of late.  I had a battery die, and then in trying to figure out what went wrong, realized the voltage across the terminals was up to 15 while the bike was at 2k rpm. 

I am terrible with electric systems, and a knowledgeable friend installed it for me.  It charged at around 13.5 when installed, but something must have gone wrong.  Does it make any sense that it just failed, and I should replace it with another DOHC reg/rec, or is there a better product available if i want to stick with solid state?

[iron_worker]

You could have a poor connection on your voltage reference line. If there is a lot of drop here then the regulator will see a lower voltage than actual and will try to over correct.

IW

[dave500]

bit of an old thread?you can use that type of rec/reg for just the rectifier part then use a different regulator to suit like this,or just buy the correct type of combined unit,using one of those permanent types you have to wire the field to be on all the time,it never gets a rest and excess voltage is dumped to earth and sweated out as heat,youll mostly end up over charging like you have.

thats a boldor rec/reg used for its rectifier with a bosch RE57 electronic regulator.

[scottly]

The regulator referred to at the start of this thread is not for a permanent magnet rotor, Dave. It will work, but the field wiring has to be changed to work on an SOHC, or it will be always in "full on" mode.

[dave500]

ok thanks scott,i only skimmed over it.

[bryanj]

Probable reason for failure, assuming that the battery was kept topped up to full line, is either a volt drop on the sense line(usually a bad connection) or a corroded ground connection. 15 Vdc is not too far out as the electronic type are suppose to regulate at 14.5Vdc