KZ750N- testing plug wire shorts through handlebar

I was just testing for spark jump on my 82 750 spectre. Using an adjustable gap jumping tool I checked plug wires 1 and 2 and saw a blue spark jump 8 mm with no problem. Connecting the tester to 4 plug wire and cranking the motor produces no spark at the tool but good clicking around the kill switch and ignition switch. It was not strong enough to hurt me but I could feel it! I was testing spark because the bike seams to miss fairly regularly at idle and above and the 1 and 3 exhaust pipes run about 50 to 100 degrees cooler. The neutral light also goes out when you run the engine above 2000 rpm. I know this all sounds like a short but where do I start looking given the above conditions. The bike run very good last summer until I installed new intake boots and removed the air injection system. The old boots were leaking very slightly. I thought maybe it was time to have the carb rack done by Oldschool, but that did not help the missing. Any thoughts?

Are you sure the plug wires are connected correctly? One coil services cylinders 1 & 4, the other one goes to 2 & 3.

Get the factory sop manual and double check ever wire and connection that you might have fiddled with while replacing the boots and removing the clean air stuff. Did you connect the reed blocks or block them off?

Perhaps high intensity voltage is leaking through old deteriorated spark plug wires to engine and/or chassis.

Good Fortune!

I did connect coil(s) primary and secondary wiring correctly, even went so far as to get the polarity shown in the Kawasaki Shop Manual. After removing the air valve I ran a piece of tubing between the reed valve covers. Would any of these suggested problems cause the neutral lamp to go out when reviving? I will also swap out plug wires with another set I have, checking the resistance first. Thanks for the tips. One other clue- the self cancelling turn signal unit does not work any more.

Finally got around to working on the 750 some more. Installed new battery and checked and cleaned a lot of wiring connections. Pulled carbs one more time and checked all jets and needles, and checked service fuel level. The only thing I found was a loose connection at the neutral switch, no more light going out. I have not been able to replicate the shock I received but cleaned both left and right controls on handlebars. I had pulled the pickup coil to test my other bike, so I checked the air gap which is 0.019" both sides. The pickup coil tested fine as did the cylinder coils. Bike still misses at all speeds and #1&#3 cylinders still running 90 degrees cooler. About the only thing left to do is check valve clearances, but need to get gaskets first. Can the valves go out of spec. as fast as 2 weeks of just sitting??? And does this sound like a valve in 1 and 3 cylinder staying open???

Thanks for any help.

The valve clearances will close up, not open, so if the engine seems less noisey, check the lash, as you can burn valves, a $$$$ repair.

Thanks for the reply,

I did know that about valve clearance, sorry for stating it wrong before. That still doesn't sound like the problem on the 1 and 3 cylinders not firing consistently. The exhaust seems to smell rich, which would make sense, but no black smoke yet. Let me do a compression check and see what's up. I don't have a leak down tester. Would a wiring problem cause 2 cylinders on different coils to misfire? I did check the plugs and wires, but will do a plug swap after checking valves. Could removing the air switch and running a piece of tubing between the covers make any difference? I believe I left the reed valves in but don't know their condition. I will check that when checking valves. One last thing, the voltage an the red wires at the coils was about 11.2 volts on each side, ignition on but not running. After pulling the valve cover do I need to remove the automatic cam chain tensioner and reset? My manuals don't touch on this.

Thanks again.

Did you redo the spark plug wire connections? Just in case... the spark plug wires untwist from the coils.... unscrew the ribbed compression boots, then the wires.

The coils may test fine w a multimeter, but they can be bad as the resistance checks won't catch internal shorts.

Something you can try is to ride the bike at highway speeds, then stop & check the coils to see if they are getting hot to the touch - press hard w your fingers. don't get burned by the valve cover. Mine were very hot, so I installed green Dyna 3.0 ohm coils. The grey 2.2 ohm coils are a better match for the stock ignition, but I got the green in case I had to end up getting the Dyna S ignition.

Also, I know you installed a new battery & it probably isn't the problem, but make sure the battery is properly charged & good.