Topic: Honda CB 650 1980 Non start

[Gerwan71]

Hi

This is my first post so thank you in advance for any information given to help.

So my 1980 CB650 is currently not starting? I've got a new battery but when I press the start button nothing happens at all, I bridged the solenoid to the starter and it runs but there is nothing on the button. The headlight doesn't dip in brightness and there is no clicking on the solenoid. Everything else works as it should like the lights etc.

If anyone has a wiring diagram or can help I would appreciate it very much.

[scottly]

The headlight doesn't dip in brightness and there is no clicking on the solenoid. Everything else works as it should like the lights etc.

Hi Gerwan. The fact that the headlight doesn't dim when you press the starter button implies the problem is in the switch itself, as it transfers 12v from the light to the solenoid when pressed. 

[BenelliSEI]

Obvious question, have you checked your fuses?

[scottly]

Obvious question, have you checked your fuses?

The lights wouldn't work if a fuse was blown.

[BenelliSEI]

Obvious question, have you checked your fuses?

The lights wouldn't work if a fuse was blown.

Unless there are three fuses and only the lights work?

[scottly]

Here's a schematic for the 650. If you study the wiring for the start switch, you can see how it switches the 12 volt power from the headlight to the solenoid coil when the button is pressed.

[Gerwan71]

Hi

The diagram is very useful.

I've checked the red / yellow from the starter switch to the solenoid and the 12v switches but nothing happens at the solenoid itslef, not a click or anything so I think i'm going to order a new starter solenoid/relay. It's a cheap starting point so i'll let you know or if you think different then let me know.

[scottly]

When you press the button, does the headlight go out?

[Gerwan71]

Hi

No it stays on?

[scottly]

The headlight should go out when the button is pressed. When the switch is in the "free" position, the blk/red wire is connected to the blu/wht wire, powering the headlight. When the button is pressed, that connection is broken, turning the headlight off, and the black wire is connected to the red/yel wire to send power to the solenoid.
Are you measuring 12V on the red/yel wire at the solenoid when the button is pressed?
Also, there is an interlock system that prevents the starter from operating unless the transmission is in neutral and/or the clutch lever is pulled in. This provides a ground for the solenoid coil on the pink/green(?) wire when the starter is enabled.

[Gerwan71]

Hi,

Thank you so much for the help.

The 12v is at the solenoid when then button is pressed but again nothing happens to the headlight. D you have any ideas?

[scottly]

Is the trans in neutral?
Also, is this a problem that just started?

[Gerwan71]

Hi.

The bike is in neutral, the bike has been sat for a while 6 months or so.
I can get it to run if i power the solenoid with a screw driver so it's def electrical but i'm lost

[scottly]

Try pulling in the clutch lever.

[Gerwan71]

Hi.

I've tried pulling it in, disconnecting it and putting  split pin across it but i get the same voltage at the solenoid.

[Gerwan71]

The four wires on the solenoid I get power to the red & red/white and obviously the red/yellow when i press the switch but there is another which I don't know what it's for?

[scottly]

The other wire is the pink/green(?), correct? What voltage do you measure on it with the button pressed?

[Gerwan71]

Hi.
Yes that is the one, there is nothing showing on it when the button is pressed.

[scottly]

Disconnect both the red/yellow and pink/green wires and measure the resistance between them at the solenoid. From memory it should be about 3 ohms.

[Gerwan71]

Hi.
I will let you know tomorrow as I’m not near it at the moment. If there isn’t do you have any ideas?

[scottly]

Those two wires are the coil that make the electromagnet, which is what makes the solenoid operate. If it is open, or infinite resistance, the coil is bad, and you need a new solenoid. If the resistance is OK, I would try jumping the pink/green wire directly to the battery negative terminal, and see if it works with the button. If still no joy, I would leave that jumper connected, and then jumper the red/yellow directly to the battery positive terminal, bypassing the wiring harness and switches completely.

[Gerwan71]

Thank you.
I will let you know tomorrow 👍

[Gerwan71]

Hi,

So I checked the reading on the red/yellow & the green/pink at the solenoid with the plug disconnected and there is nothing it reads .OL so I guess I will need to order a solenoid.
I did also connect the yellow/red to + and the green/pink to - and nothing happened at the solenoid, no clicking or anything.

I will now order the solenoid and see how it goes 

[Don R]

 The reason that we were suspicious of the start switch is that it should turn off the headlight when pressed, and they are infamous for failing. The start/headlight contacts are encased in a plastic cage that crumbles.
 The cage was once 3D printed by someone here, but it isn't an easy repair. Hopefully yours is OK.

[scottly]

While you are at it, the stock 30 amp main fuse is a flimsy strip of metal attached with cross-head screws to the solenoid. God help you if you have to replace it on the side of the road on a dark and rainy night!! I strongly recommend that you replace it with a blade type fuse.