Bad Ignitor?

Okay, I need some experienced voices here. I'm getting intermittant firing on my 1981 KZ1000, especially during acceleration. I initially thought it may be a failing ignition coil.

Recently, I was working on a 1989 Ninja 500ES that had a problem where it would just suddenly die. After awhile, cooling down probably, the bike would start up again and run for awhile, then quit again. It turned out to be the ignitor was failing, but when it would die, I just wacked it and it would start up again. Yeah, sounds stupid, I know...

Anyway, my question is could an ignitor going bad induce my symptoms of intermittant misfires and the resulting jerking of the bike under load? Or does an ignitor always, when it starts failing, either work fully or not at all? And also, does it sound like I should open up the harness and check or replace the black and green wires going to the coils?

I did the WG coil repowering mod (because of the problem which started before the mod) and checked the ohm resistance of primary wiring. My tester returned 2.0 ohms exactly on both coils, several times. Oh, and by the way, I put new Dyna sparkplug wires on the bike just about the time the problem manifested itself, but I have gone back and checked the connections to the coils and the sparkplugs, and all seemed good.

BTW, I'm also replacing the old fuse block with an ATO/ATC fuse block, finished fabing the new fuse block harness with connector this evening and will install tomorrow. But I doubt it will eliminate the problem. Your help is appreciated.

Post edited by: Norseman, at: 2007/08/30 00:42

The ignitor? Are you talking about the pick up coils on the right side of engine.
If yes then yes it can cause jerking, sputtering, missfiring, and embarassment. If one ignitor is going bad it will shut down two cylinders. Which two are not firing?


I had been riding my bike for a while now and untill last night I found out wich cylinders werent firing. Before when it would start to happen the engine was hot and could not tell wich two were cutting out, but I did know that two cylinders were cutting out. Last night after parking it for 15 minutes, I started it and it was missing as soon as I started it, and since the pipes were cool I felt to see which pipes were hot. I found out my two center pipes were cold this narrows it down to either a coil or a ignitor, and posibly a wire, but at least I know were to look now.

In my experience with coils they can be fine at room temperature and as soon as they get hot tey will start to miss, I have also had coils not fire at all when they get really cold (winter) but be fine when they warm up, and lastly I have had coils fire at the plugs but not allow the engine to start.

Probley the best way to test a coil is with a KV tester, or spark tester. Its only $5 at a local parts store
Set it at 35 and hook it up to check for spark. If it jumps the gap (about 1.5 inches) the coil is good. This tester has never failed me in testing coils.

As far as the pick-up or ignitor I would just test for Ohms of resistance. Try to put and ice cube over one of them to get it cold then test. Then try to get it hot with a blow dryer then test. Good luck.

Recently, I was working on a 1989 Ninja 500ES that had a problem where it would just suddenly die. After awhile, cooling down probably, the bike would start up again and run for awhile, then quit again. It turned out to be the ignitor was failing, but when it would die, I just wacked it and it would start up again. Yeah, sounds stupid, I know...

Its not stupid at all. when dealing with these ignition pieces you have to remember your dealing with small windings, and you might have a very small break in the windings. It will be just enought to allow it to operate untill a change in temperature, which will contract or expand to item, and make it act up. Or hit it with a hammer to move the insides a little to make it connect.

The best way to check for a break is with a Ohm meter.

IC Igniters are only on electronic Ignition equiped bikes, and are usually under a sidecover near the battery etc.
The IC Igniters can go bad.
I had a problem with intermittant firing, and loosing a cylinder or two on some of my first rides with the Kawi Electronic Igition swap I did.
I tested the IC Igniter with a meter following the manuals procedure for which wires to test and readings.
4 wires in and 4 out. Can't remember the colors off hand.
Turns out one of the red wires on one side was not reading (Ohms) right.

Post edited by: rstnick, at: 2007/08/30 13:56

Thanks, Snakebyte and rstnick. Yes, my bike has electronic ignition, so I have pickup coils, obviously ignition coils, and an IC Igniter.

I'm trying to determine which is causing the problem. It could either be an ignition coil, the IC Ignitor, one of the pickup coils, or the new Dyna sparkplug wires I installed.

While it is probably rare that new sparkplug wires would cause this misfiring, it is possible, I would assume. What I'm trying to do is eliminate the good components in order to spend my very meager funds on the actual problem. So far, I'm going to the new fuseblock that should improve the overall system (at least that's what some folks reported who did the mod). It's done and will be installed tomorrow. Also, I am going to re-install the old sparkplugs (that I replaced with the new Dyna wires for no other reason than for fresh wires). Then I will test by going for a ride.

If the jerking persists, then it points to the remaining components; Ignition Coils, Pickup Coils, IC Igniter, or the wiring. Again, when I tested the Ignition Coils, both of them measured 2.0 ohm exactly and several times.

I did read the "IC Igniter out of circuit" test, and not being savy in electronics, I got lost especially when the manual instructs the use of their electrotester together with an ohm meter. Honestly, I don't have a clue how to test the IC Ignitor.

So, with my lack of electrical/electronic knowledge and tools, I might be stuck with replacing one component at a time until the symptoms are eliminated. I would assume that replacing the Ignition Coils would be the best place to start?

Post edited by: Norseman, at: 2007/08/30 23:48

Like I said before when coils go bad they go bad I have never had one intermitently work. Then again it is mechanical, anything can happen. Let us know cause like I said I have the same problem, and for you to replace a bunch of unwanted parts is better then me :pinch: :silly: I'm just kidding:whistle:
I'll be working on my bike over the weekend and if I find any thing I be sure to post it.
Ignition Coil Inspection And Testing

Your ignition coil may be attached to the fender or engine (externally mounted), or mounted inside the distributor cap (internally mounted). They can be tested either on or off the vehicle. Before replacing the ignition coil, we suggest you inspect and test the distributor cap and rotor and the primary voltage circuit.

Testing Externally Mounted Ignition Coils


Disconnect the distributor cap end of the coil wire and attach to the ignition tester. Attach the ignition tester to a good ground, away from any fuel lines.

A good spark tester can be made from an old spark plug gapped to 0.200".

Crank the engine and observe the tester for spark. If a crisp blue spark is noticed, the ignition coil is working properly. If a pale yellow spark is noticed, continue on to step two.


Disconnect the negative battery cable.


Note the position of each wire on the ignition coil and remove them.


Inspect the coil for leaks around the top and for external damage. If any are found, replace the coil.


In the proper service manual, locate the test specifications for your vehicle's coil.


Connect the ohmmeter to the primary studs of the coil. Turn the meter to the 0-2M ohm scale. Compare your reading to the primary winding specification for the coil. (Figure 1)

Remove either one of the meter leads from the primary stud and connect it to the coil wire lead. Reset your ohmmeter to the 2M-20M ohm scale and compare the reading to the secondary winding specification for the coil. (Figure 2)


If the primary or secondary winding readings do not fall within the range indicated in the service manual, replace the coil.


If the coil tests within specifications, refer to the proper service manual for further diagnosis.


Found a web with this info hope it helps

Come to think abnout it, and I am tire of messin around all the time with my bike and rigging it to work right. If I cant find anything over the weekend with my bike to get it running good. I'll keep riding it the way it is till winter then I'll bite the bullet and get a dyna 2000 kit w/coils. I found a site that is selling them kits for $337.00.

Hi can anybody tell me where is the best place to buy a pickup coil, i think one of mine is going bad, i have a 1981 kz 750 ltd.. thanks john.

heavy360 wrote:

Hi can anybody tell me where is the best place to buy a pickup coil, i think one of mine is going bad, i have a 1981 kz 750 ltd.. thanks john.

Probably ebay.

If you can determine which cylinder or cylinders are not firing, you can simply swap some wires, and the rotor, around to determine which item is the cause.

If you swap the primary wires on the coils, and flip the rotor on the advancer, and the misfire moves to the other cylinders, then you know the coils are good. If the mis stays in the same place it's the coil or the plug wires.

If you determine the coils are good, then put the primary wires back to normal.

Next, you swap the pickup wires at the ignitor (swap yellow with black, and red with blue). If the problem stays on the same cylinders, it's the ignitor that's bad. If the problem moves to other cylinders, then it's the pickup that's bad.

When you do this you should keep notes on where every wire started out and note where the rotor points to in relation to the advancer. Note if the point is pointing toward some writing on the advancer mechanism.

Post edited by: loudhvx, at: 2007/08/31 13:32

Well, folks, I found the problem. After all the troubleshooting and frustration, it turned out to be a very simple issue.

As I have said, I had replaced the original (and quite old) sparkplug wires with brand new (and red like my 1981 KZ1000 bike) Dyna wires (that's a clue), so I knew it couldn't be bad wires causing all the missing, jerking, clunking feelings.

The bike has electronic ignition. Hmmm. Did I consider that little tidbit of information? Nope. But the more I thought about it, the more I kept wondering about it. So, I put the old wires back on the bike, except for just one little wire for #1 sparkplug, as I had cannibalized the plug cap to fix a shorted plug cap on my son's 1981 GS650.

Bike ran even worse, if possible. So I stopped by AutoZone and bought one wire, and replaced the last of the "brand new Dyna sparkplug wires". The bike fired right up, and ran like it has never run before. No missing, faultering, clunking, jerking!

Turns out I had purchased unshielded Dyna wires, and since my bike has electronic ignition, it requires shielded cables.

I thought I'd post this outcome just in case someone has this problem, and hasn't thought about about shielded versus unshielded sparkplug wires. In retrospect, though, the problem did cause me to do a lot of great mods, and learned alot from the advice from folks helping me through this. But the root cause of the problem was something I had done to improve the bike. Sort of funny, I thought...

Post edited by: Norseman, at: 2007/09/02 07:29

Post edited by: Norseman, at: 2007/09/02 07:30

You sure you don't mean resister plug wires instead of shielded? I haven't seen shielded plug wires since I quit working on military vehicles