78 KZ650B -- Not Starting

I have a 78 kz650 that has been running decently and had no real issues.

I rode it today for 30 min. and all was well when I parked. Came back later, turned the key and no power anywhere. I checked the fuses and the main fuse was blown. I changed with a spare and it blew immediately. I jiggled some wires and tried disconnecting and reconnecting some of the various connectors. Tried another fuse, blew immediately.

I decided at that point to trailer it and bring it home.

I tried connecting the main leads without a fuse (probably a real bad idea) and that didn't accomplish anything. I put in a blade style fuse and that one is now "stable". I now have power to all lights and switches but the starter switch doesn't activate anything.

I've checked the continuity on the kill switch and the starter switch (all the way back to the solenoid) and they seem to be functioning.

So, I checked the points. I don't see any spark on the points when I kick start it. When I continuity test the points to ground I get a tone. Not sure if thats good or bad. I did a voltage test and neither have any voltage when tested from negative (body) to the wires on the points.

The starter solenoid cranks if I short it on the top terminals. I even tried replacing it with a spare. No joy.

I did a test of the coils and both are at about 4.5 ohms. Seems good.

I see that there are many threads on electrical issues, starting issues and the like. None seem to have the same scenario though.

I'm not sure what to check next.

Could it be the condensers? I don't know how to test them.

Should the points have voltage at all times? They don't seem to but I think at one point they did. Maybe a short that ruined something else when it was shorted?

Is the starter system related to the system that supplies power to the plugs? By that I mean, what would cause both the starter to not operate via switch and the points or coils to not get power?

As you can tell this is my first adventure into the electrical system.

Most times when you blow a fuse there is a direct short that causes it. Many times it is in a location where wires can rub - like under the tank, or at the neck where wires come from under the tank, in the headlight, or at the handlebar switches. Do yo have a wiring diagram?

I do have a wiring diagram, 1 from clymers and a color coded one from files here.

I checked all over and I can't find a short. A blade type 20A fuse is in there now and not blowing. Assume that means what evr shorted it originally is not currently shorted.

Should the points have voltage at all times? They don't seem to now but I may be testing them wrong.

One thing I can't figurre out is this black plastic terminal below the rectifier. It has several wires going to it but doesn't appear to connect to anything. One of the wires coming from it goes about 6 in. and is unterminated. It has 12v. Not sure where its supposed to go but it is just hanging out doing nothing.

quick650 wrote:

One thing I can't figurre out is this black plastic terminal below the rectifier. It has several wires going to it but doesn't appear to connect to anything. One of the wires coming from it goes about 6 in. and is unterminated. It has 12v. Not sure where its supposed to go but it is just hanging out doing nothing.

A picture of this area would help

Hopefully the picture is self explanatory. I'm not sure what that block is that the wires are attached to. The black one that is unattached is a real concern. It has 12v at with ignition on and kill switch off.

I'm going to get a new battery but I'm not holding out hope on that. I would think even a really low battery would delivery zero voltage to the points.

Although that "spare" 12v wire is odd I don't think its at the heart of the issue. Its currently not touching anything so I imagine its at least not causing more damage.

I started thinking, if there is no voltage to the points then there must be a cause. I thought, kill switch is bad so I tested that every which was and it wasn't all adding up. Not sure what was off but its odd. I took the switch apart and connected the leads and the lights dim and the rectifier clicks. So, while not the root of the issue, looks like the switch might have gotten fried in the process. Makes me wonder about the start switch as well now.

Anyway, on I pressed. I figured, why not eliminate the 3 feet of wire between the controls and the connectors under the tank. So, I went back to those connectors and disconnected the controls. Then cross the leads (simulate kill switch on)at that point. Same drain on lights and rectifier click.

In all that the blade fuse never blows.

So, on I march but with no understand of where I'm headed other than to rule out as many parts and wires as I can.

Looks like the coil-relay modification was installed. You'll have to figure out how the wiring was modified and find how to correct it.

OMR, any suggestions?

That coil-relay mod, whatever that is, sounds feasible.

That yellow wire in the block goes to the starter solenoid. The others head up to the coils and I'm not sure where else.

Is there any article or doc on that modification. Not sure what it does or how it does it.

quick650 wrote:

That coil-relay mod, whatever that is, sounds feasible.

That yellow wire in the block goes to the starter solenoid. The others head up to the coils and I'm not sure where else.

Is there any article or doc on that modification. Not sure what it does or how it does it.

Click here > www.wgcarbs.com//index.php?option=com_co...view&id=12&Itemid=26

Good Fortune!

What does the plug in question plug into? Is it a relay?

This is for sure what has been done. The relay on my bike is deceivingly small so I thought it must just be a termination point or some junction.

So, I suppose to further diagnose this I could get a new relay or just set things back to stock for the moment.

Any other suggestions?

They are not that expensive but you could also run a test by unplugging from the relay, and then jumping the correct ends in the plug and see if you get power to the coils and points. If so that would make me think the relay needs to be replaced. If not then it would appear there is an issue with the wireing. I know that I have spent the better part of a day cleaning, tightening and repairing and packing with dielectric grease - all of the connections on my bike. At least I know that they should not be a problem in the near future. It also required me to check all of the wires for breaks or rubbed off insulation.