Vz800 -97 only runs on one cylinder possible broken wire.

Helped a friend to fault find her VZ800 -97 today.
The bike have been standing still during the winter, tank, fenders, tripple tree have been at the paint shop during the stand still.
New handlebar with internal wiring, lengthened wires and cables to fit the new bars.

When she tried the bike it didnt run well. The exhaust from the front cylinder is cold.

Started to check the spark plug on the front can, no spark there.
Took the plug from the rear and switched positions. no spark from the front coil with this setup.
switched coils between front and rear. Still no spark on the front one.
Used a multimeter to check the ohms on the coils, and cables from the coil to the plug. They are all the same.
Measured Volts between the thicker cable that goes to the coil and ground. There is a constant 12V on both cables.
Took out my spare CDI that i have. Still the same symptoms.
Took the incoming cables to the rear coil and put them on the front coil. Then the front has a spark and not the back.
Checked the cable (Black w. Yellow trace) with a summer and the cable is ok.

Tired to read the wire diagram to figure out how the thing is wired previous to the CDI. But couldnt figure it out since its all black and white and the lines gets mixed up all  the time.

An idea i have is that there is two different 12V cables coming in to the CDI, one for each coil. Can someone confirm that ?
Does anyone have a picture of the CDI with the pins marked out. What is comming in on each pin and where it leads ?

The other idea i have is that the sensors that gets the signal to fire a spark to the CDI is broken. But i havent figured out how that works just yet.

Anyone with expereince in this field that can give me some hints and pointers ?

did you swap plug leads at the same time?

Leads = the cable between the coul and the plug ?
Then we swapped them between the coils back and forth.  and it is allways the rear that works. Untill we took the  cables that goes from the cdi to the rear coil and connected them to the front coil.  Then everyghing worked with the front coil no matter the setup.
But the cables from the front coil couldnt reach the rear coil so we where unable to test  them on a different position. but since we changed everything after those wires between the sides i would say that it is something with the cables to the coils. Or the cables to the CDI if there is one 12 for the front coil and one for the rear comming in to the CDI.

Have you tried measuring the voltage on your coils, this should give you an idea of what you are looking for on the faulty bike.

Hello twenty2,
You asked ~
"An idea I have is that there is two different 12V cables coming in to the CDI, one for each coil. Can someone confirm that ?" 
Yes you are correct mate, B/Y  ( Black with Yellow tracer) and B/G (Black with green tracer sometimes is a white wire) see diagram below.
You seem to have traced the fault to faulty wiring to the front coil, your own testing has shown coils work if they run off rear coil feed,, you swapped out the ignitor box with your spare so that seems ok and you have swapped coil/plug leads and all work on rear coil feed,, I would be checking for continuity and dirty connections on the front coil feed.
On some VZ Marauders the B/Y link to the fuel pump, check that wire also.
The Black wires from both coils link to the starter and engine stop switch on the bars via the O/W ( Orange with white tracer) check these wires closely for breaks and dirty connections,,, the Kill Switch and Starter Switch are a source of known problems on the VZ, I have read of people having intermittent bad starting and miss-fires due to faulty switches  so I have included a procedure to check these.

Sorry I have to do multiple posts in having computer problems,,

Start and Kill Switches,





Alternate wiring , B/Y to fuel pump,



 I hope this is of some help mate, keep us informed how you get on, I would like to see you solve this fault.

thanks two-bears.

I will try to look in to this later this weekend.

Another thought is to take the +12V from the working coil and just forward it to the not working one and see if it starts to ignite on both plugs.
As i understood it it is the ground that close the circuit and works as a switch so in theory it would work if it is just the +12V cable that is messed up.