Topic: Can anyone catch this electrical demon? FIXED THANKS ALL

[Fish]

I have tried to solve this problem myself but I am pretty weak when it comes to electrical.  I was hoping that these symptoms might be specific enough to help one of you identify what the cause is.

The bike: '79 cb650 - the one I sold to a close friend when I bought my 550.

The symptoms:

Starting the Bike:  When I start the bike the handle bars have to be turned all the way to the left.  If the handle bars are straight, the engine will turn over -> but will not ever start.  I can hold the starter down while the handle bars are straight and it will continue to try to start and as soon as i crank the handle bars to the left, the engine will fire up.

Weird Quirk:  If the bike has not been started, but the key is turned on, the head light will only illuminate if the handle bars are turned all the way to the left.  Once the bike has been started, the head light works at any angle.

Engine Cutting Out:  The engine will randomly cut out while riding (all the electrical completely shuts down - no lights, signals, etc.).  I notice it happens 95% of the time while cornering (in either direction).  Usually i have to come to a complete stop, and turn the handle bars all the way to the left (this seems to "reset" the electrical system in some way and all power is restored to the bike).  Then I can restart it and continue to ride (this is very annoying when driving in rush hour traffic).  The group of cables going through the steering column obviously has something to do with this.  Sometimes, if the engine cuts out while driving, I can just leave it in gear, and quickly reach down and jiggle the wires a bit and the bike will fire back up before the bike comes to a stop.


Any and all ideas appreciated.  Thank you,

- Chad

[HondaMan]

Two things come to mind:

1. Loose connector(s) inside the headlight.
2. A broken, but close-together-ends wire in the harness, right at the point where it flexes by the steering head.

Pretty common, really... 

[Fish]

I hadn't even thought about the headlight...

If it was the second option and one of the wires in all that spagetti is severed, how would I find it?  Would one of those probes that measure current work - just hook it up and play the 'one of these things is not like the other' game until I found one that wasn't carrying as much/any?

Cheers,

- Chad

[Kelvin8]

Don't know if this applies to your bike, but I was recently told that 74-78 550 and 750s had a defective ignition switch assembly. The plasict part that inserts into the metal housing was prone to working loose. The plastic was too soft and the ... watcha callits ... tabs that held it into the metal housing were prone to ... well, not holding the piece in place. Honda made and sold a replacement part. The defective part is white plastic, the replacement is black plastic. The symptoms you describe would be consistent with this fault, but again, I don't know if it applies to your bike. Apparently it does apply to mine.

Kelvin

[750goes]

I would have a look inside the headlight bucket and see if your headlight mounts are nice and tight,, mine had an EARTH wire attached on each side. If they come loose or have bad connections could quite easily work one way then not the other with all the wires push/pull etc.

just a thought..

[Bob Wessner]

I would have a look inside the headlight bucket and see if your headlight mounts are nice and tight,, mine had an EARTH wire attached on each side. If they come loose or have bad connections could quite easily work one way then not the other with all the wires push/pull etc.

just a thought..

A good thought. Mine failed on one side due to corrosion of the ground connection. It seems the interior of the headlight shell really is not all that weather proof. I had to fabricate a better connection temporarily which fixed the problem. I acquired a set of the ground connectors from another member and plan to replace them this winter along with some other work.. unless my jury rig fails sooner.

[750goes]

Bob,

I am currently redoing my whole harness, and after finally getting the blinkers/winkers working properly, I decided that I should tidy things up, particularly as the wiring falls out of the headlight bucket every time you move the steering. - guess What, they don't work now. Try again tomorrow....when it's not so cold.. Both my earth wires were corroded, I moved one slightly and it broke off...

[Bob Wessner]

I moved one slightly and it broke off...

That's exactly what happened to me when I went to investigate the failing blinker.  My jury rig consisted of drilling a very small hole in both pieces after cleaning them and using an equally very small screw to join them. I real pain because of how small, but it has worked so far.

[Fish]

Thanks for all the tips.  I will open up the headlight bucket and see if that's where the problem is.  I'll let you know once it's fixed  .

- Chad

[Boomologist]

Don't overlook the ground connection from the front end to the frame.

Also, check the connectors that go to the coils and if there is a connector block under the gas tank near the steering neck. These can come loose.

[Fish]

Boomologist,

Thanks.  I will check my Clymer manual to see if it shows where the ground connection should be.

[rory]

had the same thing with my 78 750K along the same lines as Kelvin8s response the white plug that goes to the ignition was the problem when the steering is hard cranked in tight spaces it pulls on the connectionhope this may help

[Raul CB750K1]

I would say forget about the headlight; I bet is a broken wire on the wire loom at the steering stem, where the wire bends due to the moving handlebar.

I would start the bike with the handlebars to the left, and then will get the individual wires and try to pull them apart, until the bike stalls. You will see the cable looks fine from outside, but the wire strands inside are broken. You will be able to elongate the wire -as it's only plastic- splice it and you're good to go. To speed things up, check wich color is the positive lead that goes to the coils; I bet it is. Don't overlook the advice given about the ignition switch.


Raul

[KB02]

One other possibility that I am surprized that no one mentioned is a fraid wire either in the headlight bucket or, more likely, in the steering stem. If that were the case it would most likely be connected to either the engine cut off switch or the starter switch. I'm not sure abut the 650, but I know that my 750 has a headlight cut off switch attached to the starting mechanism that kills the light to give more power to the starter. Especially with your headlight cutting ot every now and then, that's what makes me think it might be a fraid wire grounding out somewhere.

[wardmoto]

mouse nest in the headlight

[jtb]

Fish,
I had a similar problem, except that everything would go dead except when I turned the bars all the way to the left.  It was the plug on the end of the harness that goes into the ignition switch working loose.  The tabs on the white plastic shroud on the switch were broken off.  I got a replacement kit from Sirius, it doesn't fit the switch as well as I would like.  I wont know how it stands up until I get the engine back together. 

[Fish]

Haha, oh so that's where all the confettti is coming from. 
Thanks everyone for the suggestions.  I forwarded it all to my buddy and he try it this weekend and let us know what happens.

Cheers,

- Chad

[Fish]

Update,

I just talked to my buddy and, using to the suggestions in this thread, he has fixed the problem.  Turns out that it was a broken wire after all.  The ground wire was 'almost' broken off the grounding point under the tank. 
Thanks, everyone for your help! 

- Chad