1 cylinder dropping spark

[turbodave]

On my zxi I have a cylinder dropping spark after about 3-4 minutes riding. This just happened all the sudden with no warning. The compression is 120+/-3lbs across all 3 holes and the resistance on the primary and secondary windings are in spec. While at the lake yesterday doing some troubleshooting I pulled the plugs as soon has it started running on 2 cylinders and 1 cylinder is definately not getting spark while the other 2 are. Can the CDI drop just 1 cylinder and still fire he other 2? I checked resistance through the plugs wires with and without the plug boots and all are about the same so I dont see a problem there. where should I look from here? Any Ideas are welcome.

[John Kubiak]

Re: 1 cylinder dropping spark

As goofy as it sounds; did you try swapping the spark plugs around to see if it could possibly be the spark plug?

Are the spark plug caps screwed on to the wires securely?

When you were doing the resistance tests on the secondaries did you try wiggling the wires from the coil to the end of the wire (to find internal breaks in the wire). What about the primaries as well?

Did you test the resistance of the spark plug caps? If they do not all measure close to the same this could be a contributing factor to your problem

Did you make sure that the primary wires in the electrical box are not getting pinched by the box cover when it is installed?

And finally, yes the CDI will trigger and fire each cylinder's spark, independent of the others.

[FastUltra]

Re: 1 cylinder dropping spark

And finally, yes the CDI will trigger and fire each cylinder's spark, independent of the others.

Not to side track from the message topic, and I think John is exactly right on what tests you should do. But I think on the ZXI the CDI fires each plug at the same time. Meaning each plug fires 3 times a revolution of the crank. There is no sensor that tells the CDI what cylinder is aproching TDC.

I would start off by chaning out the plug. On the top of the spark plug is the little metal tip screwed in all the way? If you decide it is not the spark plug I would try swaping coils with another cylinder. That would then rule them out.

[John Kubiak]

Re: 1 cylinder dropping spark

Sorry Paul, each coil fires once per crankshaft revolution....the Kawasaki's Kokusan Denki and/or Mitsubishi Electric systems trigger each cylinder independently albeit through one trigger assembly...check the magnets on the flywheel, there is one small magnet used for MAG cyl and "TDC", and two longer magnets used to trigger 2 and 3. When I was teaching PWC electrical and ignition systems, I had a "bugged" system that drove the students nuts, all we did was remove one of the flywheel trigger magnets, and it wiped out just the related cylinder.......the other two still operated correctly.

[FastUltra]

Re: 1 cylinder dropping spark

Ahh thanks for explaining that John. I didn't know that. Where did you go to school? I never really noticed the magnets being different sizes.

[John Kubiak]

Re: 1 cylinder dropping spark

I didn't go to school, I taught at the school.