wiring harness connections - 1975 Z1-B 900

Hi.
I'm getting no spark at any cylinder on a 1975 Z1-B 900. Have replaced the coils and spark plug caps. Spark plugs look good. Still no spark, although everything else seems to light up, including starter. 

I have 3 loose yellow wires going into the wiring harness connector, with one having 12.5 volts. I am not sure what they are for. Does anyone know where these wires go since the connector is missing? Maybe that's the problem?

Here are pics of the front and the back.

Thanks.

~Bob1975

 

Three yellow wires together. I bet they are the main power wires from the generator (Correction: from the regulator.). Based on that and the condition of the connectors in the picture, I reckon there could be a wide array of electrical problems. Somewhere around here, Wookie58 has posted a basic electrical diagnosis tutorial. It should be your new best friend. A can of Deoxit D-5, some tiny soft wire brushes, and a multimeter will all be needed as well.

Bob1975 wrote:

Hi.
I'm getting no spark at any cylinder on a 1975 Z1-B 900. Have replaced the coils and spark plug caps. Spark plugs look good. Still no spark, although everything else seems to light up, including starter.  Try and get away from diagnosing faults using the "throw parts and cash at it" method, generally you will buy a lot of parts you don't need before getting to the bottom of it. The connector plugs you have posted pics of are the heart of your electrical system so sorting them first should be your starting point.
How would you rate your electrical skills ? (my fault finding guide's link is in my signature and this will be helpful to you)

I have 3 loose yellow wires going into the wiring harness connector, with one having 12.5 volts. I am not sure what they are for. Does anyone know where these wires go since the connector is missing? Maybe that's the problem? See below

Here are pics of the front and the back.

Thanks.

~Bob1975


 

Bob, gotta admit that's a dirty/corroded  mess you have on Your hands there!! Those wires you're holding in your hand are from your regulator, not stator. Stator "Blue" connector seems to be plugged in and undisturbed. If the three wires are indeed all yellow then someone has replaced the original regulator. As Wookie provided the schematic for you, Pink/Lite Blue/Yellow one of each, route thru the Green Male connector and come out the Blue Female connector on junction panel. While color coded they can be connected in any order but match routing for simplicity. Considering i don't see the correct slim male connectors attached to the wires you're concerned about and missing the Green connector, it's probably an aftermarket replacement. Actually, looks like someone might of just "jammed" those wires into the Green female terminals, not ideal by FAR. Here's what the correct Regulator should look like. It's a 3-phillips, KZ900/KZ1000 only used 2-phillips head M3 screws. Also note the White female connector at junction panel is absent anything. This is where the Rectifier should plug into. And..word to the wise, if all other wiring resembles what you're showing, be prepared for a lot of mysterious intermittent  electrical issues. Regardless of seemingly all stuff works now, might be fleeting. Have fun!!   

Additional. Not knowing Your intent, riding/quick buck selling? You can salvage your existing wiring loom/harness, just strip off the old tape so you can see what lies within. Here's an original 1974-1975 Z1 Main harness and that junction panel sub-harness. I do them all the time for restorations, they are just simple electrical. Just saves time and headaches from present/future issues not witnessing problematic areas. Stitch-in-time theory.   

I would say that unless you are a competent auto electrician, Clay's "off the shelf" solution is a no brainer

This Youtube video should help you sort out your electrical problems.  All wiring is colour coded, which makes it easier to connect wire to wire.  The attached photo is for reference only.  I have a 3 ft by 4 ft electrical wiring diagram on the wall of my shop

There are also videos for the engine and other major components.




 

Hardrock, you should be able to take that off the wall now and archive it. Should be by memory now, haha

Thank you for the insights.

Here are pics of my current connector board and my regulator and rectifier which appear to have been replaced a while ago. Isn't that  the regulator attached to the bottom of one coil?  

I am not an auto electrician for sure, so it seems to make sense to replace the main harness and the connector junction to avoid future corrosion problems. Also the regulator and rectifier? Is this a good time to convert the points to electronic?

Thank you again. 
~Bob

No, that's not the regulator.  That is standard on all Z1B's and I've forgotten what it does.  I'm. sure Asphalt knows.

Normally the regulator is mounted under the battery box.  I see your original rectifier has been removed so I assume someone replaced the original regulator and rectifier with a combination regulator/rectifier.  

Normally the blue plug comes from the alternator located inside the left engine cover.  There are 3 yellow wires from the alternator to the blue plug on the plug panel.  I see your blue plug doesn't have yellow wires, so someone has modified the wiring to accept an updated regulator/rectifier combo.  Follow the wires on the blue plug and you will find your regulator/rectifier.

 

That device by the coils is your brake light failure relay. If you blow your brake light that will light the brake light switch on you tach. Man If I were you looking at that mess I would get the complete main harness and the small harness on the right side of the bike and while you at it probably the harness that goes back to the tail light. They are all available. Then buy a regulator/rectifier combo unit from Z1 enterprises and go with a Dyna S electronic ignition system. How dos the plug look coming from the alternator. You can also buy pigtails to replace that assembly, just cut off the old and solder in the new. Also you might want to search for the wired George relay to feed the ignition system. Do you know someone the is proficient with electrical problems because you need a lot of work on the system by the looks of what you posted. 

Fantastic! 
I think it's wise to upgrade the wiring harness and  connectors.
Is there any advantage to keeping the points?

The person who used to work on the bike went out of business.
Thanks.
~Bob