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Need a hint with wiring of CB750C

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XS-Leo

Need a hint with wiring of CB750C

Hello,

i friend of mine bought an CB750C, which is from about 1981 and was not on the road for years.
I started with cleaning the carbs and so on.
There is a long way to go, new airfilter is necessary, clearly new oils (fork, engine), new brake-tubes, the front brakes should be cleaned, and so on. But it is worth, the bike is not in that bad condition.

Trying the electrical functions i see a strange behaviour:

Ignition on:
Head Light = OK
Turn-Lights an turn Control = OK

But:
Brake-Lights, front Brake (?) = not OK
Oil-Pressure-Control = not OK (OFF)
Neutral = not OK (off)

If i try to start the engine, the Oil an Neutral control light are dimmed on. (Sorry, i am not a native speaker, i hope you understand, there are on, but not bright...) and the engine is turning.

So far i
... opened all connectors, cleaned and oiled them
... checked the fuses = OK

Does anyone know this behaviour by experience?

THX for every advice,
Leo

Nothing is really as it shows....

TOOLS1

Re: Need a hint with wiring of CB750C

Administrator

The indicator lights are not very bright, and will dim when the engine cranks, so they are good. You brake light bulb might be burned out, or a bad/broken connection.
TOOLS

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1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
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XS-Leo

Re: Need a hint with wiring of CB750C

Thanks for Your hint.

But: I wrote: the lights are off, whn ignition is on.

I found the reason and solved the problem:

Reading the wiring diagram i measured the resistance from each connector-block to the other.
In result there has been no conductibility from the connector in the lamp to the middle contact of the bulb-holder.
So i dismanteld the cable harness and found a lot of green dust from the clamp which should originally connect the plus-wires .... but the clamp was ... corroded, better: dissolved in dust.
Building some clamp, so now is everything fine.

The rebuilding of this bike is going on, after solving this i made the first try whith the cleaned carbs: It runs immediately! Very fine. now i need some parts to prepare the whole thing for the german TÜV.
(In GER you have to officially chaeck your bike and car for technical safety reasons... o speed limit, you know...) :-)

Nothing is really as it shows....