Topic: Charging help

[zuehl666]

1971 cb750 k1, new reg rec combo, new battery, all custom wiring harness. So the issue I'm having is figuring out where I should wire in the field coil wires. The green and white from the stator. I have the three yellows to the three yellows on the reg/rec. the red to batt positive and the green to ground. I'm not sure where the field wires should be, I have a black and a white on the reg, when I hook the black to field green and white to white it doesn't charge. I tired black reg and field green to negative batt terminal and it over charges. Any ideas how this should be done?

[Spanner 1]

Dude you bought a rectifier only, no regulator if your wires ( as stated ) are yellow x3 and green and red...

[bjbuchanan]

If "set up" for stock honda it is gonna be green as the ground, black as the switched hot wire (for the reg/rect possibly a hot 12v sense wire) and also the white wire to the white. You gotta hook that black to the "type" of wiring it should be, not a ground but a hot switched wire

[Bodi]

Need a bit more info: with an "all custom wiring harness",  it's really hard to diagnose from here.
I assume you have an aftermarket regulator/rectifier, since the stock one doesn't have coloured wires.
The R/R black wire is for the power to run the regulator: it has to be connected to what would be a black wire in a a stock harness - switched "ignition" +12V battery power. The regulator electronics use some power and the field coil uses a lot of power, so the regulator needs this switched power. If the black is connected to unswitched battery +,  it would power the field coil and discharge the battery with the key (and engine) off.
Then for your two field coil wires: green gets connected to ground (green wires should only be used for ground connections). White goes to the white wire from the reg/rect.
Note that by connecting assorted things to the reg/rect white and black wires you may have destroyed the unit.
Also, if you didn't get a reg/rect specifically sold for the SOHC CB750 system it may need a "reversed" field coil connection. The later (1980+) DOHC CB750/900/etc bikes used this system - you can use a reg/rect from or for these bikes but the field coil wiring is slightly different and requires modification of the stock harness to use in a SOHC model.

[zuehl666]

Need a bit more info: with an "all custom wiring harness",  it's really hard to diagnose from here.
I assume you have an aftermarket regulator/rectifier, since the stock one doesn't have coloured wires.
The R/R black wire is for the power to run the regulator: it has to be connected to what would be a black wire in a a stock harness - switched "ignition" +12V battery power. The regulator electronics use some power and the field coil uses a lot of power, so the regulator needs this switched power. If the black is connected to unswitched battery +,  it would power the field coil and discharge the battery with the key (and engine) off.
Then for your two field coil wires: green gets connected to ground (green wires should only be used for ground connections). White goes to the white wire from the reg/rect.
Note that by connecting assorted things to the reg/rect white and black wires you may have destroyed the unit.
Also, if you didn't get a reg/rect specifically sold for the SOHC CB750 system it may need a "reversed" field coil connection. The later (1980+) DOHC CB750/900/etc bikes used this system - you can use a reg/rect from or for these bikes but the field coil wiring is slightly different and requires modification of the stock harness to use in a SOHC model.

Thanks a lot, thats very helpful. I think I know where I went wrong now. I bought the reg/rec combo for that bike from dime city which should be a direct replacement but I made a custom harness so it's a little trickier. I had the  black from the reg in the wrong place so it wasn't powering the regulator.

[cheftuskey121]

Not to go too off topic but have you updated your build thread? I love the look of your bike man!

[zuehl666]

Not to go too off topic but have you updated your build thread? I love the look of your bike man!

I will tomorrow. I'll upload some new pics. I had a couple issues to work out with the tank, but it's all done now. I just have to fix the charging issue and put new tires on.

[zuehl666]

Ok, so I had to order a new reg rec because I fried the first one by wiring it wrong which we had discussed. I ordered the same one I did last time, says on the description on the site for 750k BUT when I got it I see the wires are slightly different and 750K is not listed on the box. Do you think brown-reg to switched positive and green-reg to white from field sensor? Then green from field sensor to ground??

Need a bit more info: with an "all custom wiring harness",  it's really hard to diagnose from here.
I assume you have an aftermarket regulator/rectifier, since the stock one doesn't have coloured wires.
The R/R black wire is for the power to run the regulator: it has to be connected to what would be a black wire in a a stock harness - switched "ignition" +12V battery power. The regulator electronics use some power and the field coil uses a lot of power, so the regulator needs this switched power. If the black is connected to unswitched battery +,  it would power the field coil and discharge the battery with the key (and engine) off.
Then for your two field coil wires: green gets connected to ground (green wires should only be used for ground connections). White goes to the white wire from the reg/rect.
Note that by connecting assorted things to the reg/rect white and black wires you may have destroyed the unit.
Also, if you didn't get a reg/rect specifically sold for the SOHC CB750 system it may need a "reversed" field coil connection. The later (1980+) DOHC CB750/900/etc bikes used this system - you can use a reg/rect from or for these bikes but the field coil wiring is slightly different and requires modification of the stock harness to use in a SOHC model.

[scottly]

This is a generic regulator; the 650 has a different system than all the other SOHC 4s, and the color codes don't match any of them. My best educated guess would be to wire the red to battery +, the black to chassis ground/battery -, white to the white field wire ("phase input from stator" makes no sense at all), green to the green field wire (directly, not grounded), and brown to switched ignition.

[Xnavylfr]

Since there are 3 white wires, they hook to the 3 yellow wires from stator.The brown and green also hook to the wires from the stator.
This may help ,but remember this diagram is for a DOHC R/R to SOHC wiring.

http://www.hondachopper.com/garage/reg_rect_diagram/reg_rect_diagram.html

The BROWN may hook to the white  wire and green to green from the stator. The diagram has 8 wires and yours has 7 , it shows an extra wire to juice the R/R from the IGN.

Xnavylfr(CHUCK)

[Spanner 1]

Here ya go....

RED to battery +
BLACK  to ground ( use green @ 'old' regulator )....( Honda uses Green as ground....)
BROWN to black ( from 'old' reg. )..... ( Honda uses Black as 12v when ign. 'on' ... )
GREEN to white ( from 'old' reg. ).... ( White is the power feed to the field coil... )
3 x WHITE to 3 x yellow ( no order to which white to which yellow )
 

[Xnavylfr]

http://oldmanhonda.com/MC/wiring750K1.html




Xnavylfr

[zuehl666]

This was the correct way, I was getting thrown off because my battery was draining when the bike was off. I thought i didnt have the brown hooked up to a switched positive. Turns out the battery is just draining by itself with no parasitic draw. When its off the bike and on a charger it starts to deplete as soon as i take the charger off. Its brand new, i'll have to try to exchange it.

Here ya go....

RED to battery +
BLACK  to ground ( use green @ 'old' regulator )....( Honda uses Green as ground....)
BROWN to black ( from 'old' reg. )..... ( Honda uses Black as 12v when ign. 'on' ... )
GREEN to white ( from 'old' reg. ).... ( White is the power feed to the field coil... )
3 x WHITE to 3 x yellow ( no order to which white to which yellow )