1981 honda cb750 custom exclusive ELECTRICAL PROBLEMS

[brendan]

I have a 1981 Honda cb750 custom exclusive.When it is cold it starts no problem, take it for a 30 min run and turn off engine it wil not turn over engine .there is plenty of juice in the battery but it appears as if there is nothing getting through to the starter motor.I let it cool down and it starts no problem.Thanks Brendan
 

[Re-run]

An idea for you. Keep in mind I have a 78K and I still have a kick start, if I remember, you do not.
Do you get lights and such when you turn on the ignition? I am going to assume yes for this.

Turn the key on and jump solenoid. If the starter spins, then the issue is "probably" the solenoid. It might be getting hot and not working right.
Another issue may be connectors are corroded up and the heat is somehow affecting them.

Like I said, I have a 78 sohc so my electrical is somewhat different from yours so these are just ideas.

[brendan]

Yes lights ect are all working when I turn on ignition.after 5 mins it
tries to make a effort to start simulasr to very little power in
battery then after about half an hour it starts ok . I will try your
sugestion when i get home next week.thanks
On Fri, Mar 26, 2010 at 2:26 PM, Re-run [via Honda CB750'S]
<[hidden email]> wrote:

> An idea for you. Keep in mind I have a 78K and I still have a kick start, if
> I remember, you do not.
> Do you get lights and such when you turn on the ignition? I am going to
> assume yes for this.
>
> Turn the key on and jump solenoid. If the starter spins, then the issue is
> "probably" the solenoid. It might be getting hot and not working right.
> Another issue may be connectors are corroded up and the heat is somehow
> affecting them.
>
> Like I said, I have a 78 sohc so my electrical is somewhat different from
> yours so these are just ideas.
> The ride IS the adventure. The destination is just to get gas!
>
> ________________________________
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> http://n3.nabble.com/1981-honda-cb750-custom-exclusive-ELECTRICAL-PROBLEMS-tp535911p676589.html
> To unsubscribe from 1981 honda cb750 custom exclusive ELECTRICAL PROBLEMS,
> click here.
>

[Re-run]

Another thing to try. After you ride the bike, give it a minute and check the battery voltage.

[OTTODOCTOR]

Need more data . -- Make sure charging system puts out at least 13.4 volts @ 3500 rpm . -- Is battery voltage dropping ?? -- Check ALL starting circuit connections for corrosion -- These old girls can be eat up with corroded connections and still run  -- Jumping solenoid is good advice per Rerun -- This will tell you if the solenoid is at fault -- Could be a bad starter too . -- They can take too much amperage to turn when hot if they're failing . ( The field windings can drag against the armature if the bushings are bad ) -- Can also get an OPEN in the windings when hot , which closes up and makes contact when cold . --  Many possibilities  --- Good luck -- Otto

[dave Esch]

Not sure if this will be any help to you at all, but when I purchased my bike the PO had removed all turn signals. I purchased new parts from J&P and after hooking everything up I was dismayed to find that none of the indicators worked. Anyway I found this schematic. I believe it is a homemade schematic, but it is neat, well organized and very, very accurate. By the way, I discovered the signal relay had been removed. Threw a $3 relay from the parts store and voila!

[Re-run]

Very nice schematic, do you know which bike it is for? Honda seems to love making electrical changes!

[dave Esch]

Oh yeah, sorry guys. This schematic is for a 76 750. Now as I am only in my second year of enjoying these bikes, I do not know which bikes would have similar electrical systems. That's what Re-run is for.

[Re-run]

I can say a good portion of this would not work for the dohc bikes. It will cover most of the wiring for the 72-76 I think.
Either way, I am going too upload it to my hosting site where I have the manuals.
Color diagrams are excellent.
I keep adding what I can so if anyone has diagrams like this, let me know.