Author Topic: CB900F Reg/rec on CB750 K8  (Read 1860 times)

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Offline mixstup

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CB900F Reg/rec on CB750 K8
« on: January 28, 2012, 04:02:01 PM »
Hi Guys
I tried a search but no luck,
Is there a topic already started on how to fit the reg/rec from an '82 CB900F to a '78 CB750K8.If not ,has anyone done it? Can anyone offer some help with a wiring schematic..Thanks

all the best

mick

Offline mixstup

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Re: CB900F Reg/rec on CB750 K8
« Reply #1 on: January 31, 2012, 01:49:48 PM »
Bump! :o

Offline Old Scrambler

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Re: CB900F Reg/rec on CB750 K8
« Reply #2 on: January 31, 2012, 02:11:37 PM »
I don't know if interchangable...........but the 900 has CDI..........which can also be transferred to the 750 sohc with a little work.
Dennis in Wisconsin
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Offline Spanner 1

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Re: CB900F Reg/rec on CB750 K8
« Reply #3 on: January 31, 2012, 04:27:45 PM »
The 900F has a wound rotor and brushes..... a different type of alternator than the SOHC's. Not a suitable reg/rect. combo IMO. for your '78 750. Lots of folks have installed the unit from Oregon Motorcycle Parts. What's wrong with the stock one and why do you need/want to change it out ?
If your sure it's a carb problem; it's ignition,
If your sure it's an ignition problem; it's carbs....

Offline Danno

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Re: CB900F Reg/rec on CB750 K8
« Reply #4 on: February 01, 2012, 02:14:23 AM »
the alternator on the cb750 is three phase and requires a 3 phase rectifier to work
when you own a motorcycle the wife does not have to find you handy she just has to find you

Offline mixstup

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Re: CB900F Reg/rec on CB750 K8
« Reply #5 on: February 01, 2012, 04:15:13 AM »
I did another seach and found the topic in electrical FAQ.I had problems last year with the rectifier and thought I would like t0 simplify the system .I have a CB9000f reg/rect...so do you think it will work?

chees

mick

Offline Spanner 1

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Re: CB900F Reg/rec on CB750 K8
« Reply #6 on: February 01, 2012, 07:32:29 AM »
You might be mixed-up, mixstup..... the CB900 r/r is not suitable....  :(
If your sure it's a carb problem; it's ignition,
If your sure it's an ignition problem; it's carbs....

Offline classic bike tuner

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Re: CB900F Reg/rec on CB750 K8
« Reply #7 on: February 01, 2012, 09:47:49 AM »
i have done it with a 400  but its not so simple
the fieldcoil must be regulated on the eart side of the coil so +12 is on the white wire and the green one goos to the regulater

perhaps i can find the scheme of it  [done it4 years ago]

hope you untherstand my englisch

gerrit

Offline classic bike tuner

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Re: CB900F Reg/rec on CB750 K8
« Reply #8 on: February 01, 2012, 09:59:30 AM »
found somthing   :D     but its in dutch   ;D 


de bol do"r regelaar heeft 2 stekkers

één met 5 draden en met 3 draden

de 5 draads stekker heeft 3 gele en een zwarte en witte

de 3 gele zijn de wisselstroom zijde van de gelijkrichter

de zwarte en witte gaan naar de veldspoel

de 3 pol stekker heeft een witte met rode band
en zwarte en groene

de witte met rode band is de +uitgang van de gelijkrichter

groen is massa en zwart =plus beide zwarte zitten aan elkaar

wat er dus moet gebeuren is dat uit de 5polige stekker de zwarte en witte uitgehaald moeten worden
en de witte met rode band en de groene moeten erin

de spanningregelaar regelt de min zijde van de veldspoel
de massa zijde van de veldspoel moet dus met een aparte draad naar de regelaar
de veldspoel is dus aangesloten tussen de plus en regelaar
dit verschilt van origineel

heb de groene draad aan het stekkerblok doorgeknipt en hier de
extra plus draad aangesoldeerd
de witte zit dus aan de witte van de regelaar

Offline classic bike tuner

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Re: CB900F Reg/rec on CB750 K8
« Reply #9 on: February 01, 2012, 10:32:21 AM »
try to translate it   ;D

the boldor unit has two plugs
one with 5 wires and one with 3 wires
the 5 wire plug has 3 yellow  -1 black  and  one whte
the 3 yello are the ac side of the rectifieer 
the black and white connects to the fieldcoil
the 3 coil plug  has a white/red  a black and green   wires
the white/red  is the +12v connection 
green is earth  -12v
bothe  black are connected to eachother

wath you need to do is
of the 5 wire plug take the white and the black one of
the whithe/red and green must be put in

the green whire from the fieldcoil must be connected to the regulater 
this one is original connected to earth in the loom
so you need to cut the whire outside the plug and connect this on the +12v  [thats a black one]
the white one is connected to the white from the boldor unit

hope you understand
gerrit

Offline mixstup

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Re: CB900F Reg/rec on CB750 K8
« Reply #10 on: February 01, 2012, 05:22:30 PM »
Im very grateful...Thanks!

mick

Offline Bodi

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Re: CB900F Reg/rec on CB750 K8
« Reply #11 on: February 01, 2012, 07:17:20 PM »
The translation is pretty confusing to me, not as confusing as the original though.
The basic difference is that the DOHC4 reg/rect puts ignition +12V power on one of the two field coil wires and controls the field coil power by switching the other wire to ground. The SOHC4 stock system grounds one of the field coil wires and controls field power by switching the other wire to +12V. Plus the rectifier is separate of course.
The wiring colors are consistent with usual Honda practice. Yellow is the rotor coil, 3 wires for the 3 phase system. Black is always switched "ignition on" +12V. red/white goes directly to the battery "+" terminal. Green goes to a solid frame ground.
You have to break the original field coil ground wire somewhere, disconnecting it from ground and connecting it to a black wire. Then the white wire connects to the other field coil white wire that was connected to your old regulator.
The system is otherwise entirely compatible with our 3-phase field control alternators. It doesn't matter if the 900 has brushes or whatever, the alternator functions the same way.
There are plenty of other other incompatible alternator systems though... the GL1100 is a good example.

Offline Spanner 1

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Re: CB900F Reg/rec on CB750 K8
« Reply #12 on: February 01, 2012, 07:55:42 PM »
I understood that it would not work because the SOHC field coil ( White/Green ) when tied to Black and White on the DOHC unit cannot give 'switching' on the Green wire as it's also grounded to case in the alternator..... at least that's what the SOHC wiring diagram shows. This would make the alt. run at max. output all the time.
If your sure it's a carb problem; it's ignition,
If your sure it's an ignition problem; it's carbs....

Offline mixstup

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Re: CB900F Reg/rec on CB750 K8
« Reply #13 on: February 02, 2012, 04:12:14 PM »
Thanks for the clarification Bodi! Thanks to all who chimed in...Im off to the shop!

mick

Offline Cross-over

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Re: CB900F Reg/rec on CB750 K8
« Reply #14 on: March 15, 2012, 06:44:29 AM »
After a lot of trouble with my old reg and rec I recently buy'd an DOHC reg/rec after reading this for my café. Yesterday I started to get it working but the DOHC reg/rec is dead. So tonight I'm gonna try it again with a new one. Because I'm Dutch I maybe have an better translation that could be a help for others:

The Bol d'or reg/rec unit has two connectors, one with five and one with three wires.
The first connector (with 5 wires) has 3 yellow, 1 black and 1 white wires in it.
The second connector (with 3 wires) has 1 black, 1 green and 1 red/white wire.

What-to-do:
- Connect the 3 yellow wires from the unit to the 3 yellow wires from the alternator (A.C.).
- Connect the red/white wire from the unit to the red/white wire from the battery/starter solenoid (D.C.).
- Connect the green wire from the fieldcoil to the black wire from (the connector with 5 wires) the unit. This green wire is original connected to frame ground.
- Connect the white wire from the alternator to the white wire from the unit.
- Connect the other black wire to an other black wire from the wire harness. This is the ignition cable that gets power when you turn your key to 'run'.

I'm now gonna fix my own bike. :)


« Last Edit: March 15, 2012, 06:46:20 AM by Cross-over »