Topic: Starter Button

[Edentulate]

Hello all, I've been reading SOHC4 for a couple years now, but this is my first post ever!

Anyhow, a quick technical question. I'm doing my first rebuild (1978 CB550K) and have little knowledge and no experience so far. Anyhow, due to corrosion I'm attempting to rebuild the entire wiring harness using some existing elements and some new.

Question:

On my start button there is the Black wire which should at some point draw from the battery,  a Yellow/Red wire which should go to the solenoid, and then there is a Black/Red wire....Where should it go to? Does this wire simply need to be grounded?

Im not great with electronics or understanding how it all works, but from looking at this 1978 CB550k wiring diagram that is my impression. But if so why isn't it green?

Data.sohc4.net/OM550/1978cb550manual.pdf

Lastly, once I get my planned personal bike's Wiring diagram drawn up completely I hope to post it here and get feed back before I spend a lot of time building something that doesn't work!

Thanks for the help!

Mark

[Frostyboy]

Mark, yours is different to my F model in that you have a headlight on feature that mine doesn't. The bk/r wire is to run the headlight, it's switched off when you push the start button.
I found this diagram which I think is correct for your machine. Go to page 182.

http://data.sohc4.net/SM500/HSM500550_16.pdf
Welcome to the forum btw. 

[TwoTired]

On my start button there is the Black wire which should at some point draw from the battery,  a Yellow/Red wire which should go to the solenoid, and then there is a Black/Red wire....Where should it go to? Does this wire simply need to be grounded?

Def. not grounded.  It goes to the headlight fuse.  The black wire is switched 12 V from Key switch.  The starter button normally connects it to the Bk/red (headlight).  But, when pushed, it disconnects the headlight and routes power to the starter solenoid Yellow/red.

[Edentulate]

Great!
Frosty boy and Twotired, thank you!

I plan on running only the electric starter, headlight, and a single LED tail light Do you think the draw from these lights will give me starter problems?  If not, can I leave the wire disconnected? And if so, Can I leave it disconnected if I use an on and off switch prior to the the lights?

[Frostyboy]

As long as you use the bl/r for the power supply to the headlight after your new on/off switch, all should be good to go. As TT said, it's the power supply to the h/light fuse.

[TwoTired]

I plan on running only the electric starter, headlight, and a single LED tail light Do you think the draw from these lights will give me starter problems?

Not starter problems, but ignition problems maybe.  Stock headlight draws 4-5 amps.  You don't need or want that load while cranking the engine.

 

If not, can I leave the wire disconnected? And if so, Can I leave it disconnected if I use an on and off switch prior to the the lights?

If "disconnected" means insulated from incidental grounding, then yes.
You should remember to turn the lights off when starting.  Or, be prepared to replace batteries more frequently.

Cheers,

[Edentulate]

Ok, mechanically I think I understand how the start button works, so I don't think I need an off switch for the lights if my only concern is having enou power for the starter. Other then that, I've been basing my wiring off very simplified wiring diagrams like the one at Oregonmotorcycleparts.com/images/OMP_SOHC_VRREM4_Wiring_Diagram.jpg

And none of them show the power for the lights running through the start button. But it makes sense. I'll run the lights using the Black/Red with a fuse between.

Thanks again.

[bjbuchanan]

What i did to simplify it was to remove the black/red from the starter button. I replaced the regular button with a regular momentary switch(normally open). I then put the black/red on the back of my headlight with a decent toggle switch.

Less amps thru the starter switch, less hard on the battery, easier for diagnostic


I believe the stock switch for you(and was for me) is called a dpst. It means normally you have a headlight on and grounded but when you hit the switch it toggles to a starter circuit on and grounded. Neat idea rly, they have those switches as well but getting them to fit can be a b!tch

[TwoTired]

Ok, mechanically I think I understand how the start button works, so I don't think I need an off switch for the lights if my only concern is having enou power for the starter.

You're not getting it.  The battery will supply all the amps needed to run both the lights and the lighting.  What happens during high current draws is the voltage sags, and the ignition relies on voltage levels to make strong spark.

Other then that, I've been basing my wiring off very simplified wiring diagrams like the one at Oregonmotorcycleparts.com/images/OMP_SOHC_VRREM4_Wiring_Diagram.jpg

The stock switch you have does not really work with this scheme.  And, your solenoid was wired differently when stock.  One side of the solenoid was grounded via the neutral switch or the clutch switch and the starter button supplied power to the other side.  The diagram you've chosen doesn't work with this scheme.  You are going to have a real bastard wiring scheme if you continue on present path, and in a couple years no one including you will remember what is wired to what during an eventual repair.  It can be made to work, but you are going to have to learn a lot more about electricity and how switches and electrical devices function.  Or, have someone else wire the bike of your dreams, imo.

And none of them show the power for the lights running through the start button. But it makes sense. I'll run the lights using the Black/Red with a fuse between.

The stock wiring system powers only the headlight from the starter switch, not all lighting.  And the starter switch routes power to the solenoid, not ground , as shown in your selected diagram.
You might be better off with an earlier right control module from a 72-75 CB, as that works directly with the wire diagram you've selected, and they have a lighting switch incorporated.

[Edentulate]

Well, based off what you said Im re-drawing my imagined wiring diagram to be more like the stock wiring. When I have it in a presentable form Ill upload it and let you tell me why it wont work, OR that it is good (I hope). My hope is to have a working diagram of my wiring scheme so that what you say wont happen...I do want to know how it is wired up in several years time, and would like to be able to maintain it myself. I was using the Oregonmotorcycle parts wiring diagram mainly because it showed a combination regulator/rectifier. 

Beyond that, the replacement Solenoid didnt come with any instructions. The node for the starter motor is labeled "M" and the Battery "B", so that is easy enough. Beyond that there are two connections for what should be a Yellow/Red wire to the Start Button and for the Green/Red Neutral switch.  These arent labeled. Will it make a difference If these are hooked up backwards?

[TwoTired]

Beyond that, the replacement Solenoid didnt come with any instructions. The node for the starter motor is labeled "M" and the Battery "B", so that is easy enough. Beyond that there are two connections for what should be a Yellow/Red wire to the Start Button and for the Green/Red Neutral switch.  These arent labeled. Will it make a difference If these are hooked up backwards?

I don't believe polarity will make a difference.
Familiar with an electromagnet?  That's what is inside the the solenoid.  When the electromagnetic coil is energized, it pulls a metal slug inside the core.  Attached to the slug is a big metal bar which, when pulled in, bridges two large contacts and connects battery terminal to motor terminal.


It's a very good idea to have wire diagram for your finished bike.  When something breaks or you want to add something, you'll need it.

Cheers,