Intermittent loss of spark on #1 & 4 cylinders

UPDATE ON 04/23/06: I found the problem! See my later posting.

I HATE INTERMITTENT ELECTRICAL PROBLEMS!!!

My KZ750H (4 cylinders) has just started a very odd problem of an intermittent loss of spark on the #1 & 4 cylinders. When I first experienced the problem, I traced the wires, and cleaned all the four pin connectors. I THOUGHT that fixed the problem, but it did not. Instead, I have observed the following pattern: (1) I start the bike (cold about 50 degress F outside), and it runs nicely on all 4 as I let it warm up for a few minutes, then hit the road; (2) after about five city blocks, the bike loses power, and I can verify that #1 & 4 are not firing; (3) I get on the bike to limp home on 2 cylinders, and after 2 blocks the bike starts running great on all four again, and stays like this without interruption for the remainder of my 12 mile trip. IT HAS FOLLOWED THIS SAME PATTERN FOR THE LAST THREE TIMES IN A ROW THAT I STARTED OFF TO OR FROM WORK.

My bike has the stock electronic ignition found on all early 1980 KZs, except I have DYNA coils.


I have not yet done the WG ignition circuit relay upgrade (I never needed to, at least until now), but I will probably do so soon. However, since the other coil is obviously working fine, that should mean I have decent voltage into the coils, right? (Or wrong?) Could it be the beginning of coil failure for the #1 & 4 coil? Could it be the beginning of igniter box failure? How do I tell which? I know it could be a bad wire (either an intermittant open curcuit, or a short to ground), but my inspections thus far have not found that.

The problem here is that I cannot tell if I am really getting the problem solved, because by the time I start to fuss around with it, the problem fixes itself.

I realy do not want to lose power on the Bay Bridge on ramp again.

Anyone care to share your thoughts, before I just replace everything and re-wire the whole bike?

Post edited by: apeman, at: 2006/03/22 14:03

Post edited by: apeman, at: 2006/04/23 18:46

Geesh... Let's try some basic troubleshooting and not make any assumptions...

1. take a multimeter with you and the next time the 1/4 coil quits working, allow the bike to run and check the voltage going to that coil.

2. no voltage? The only place you COULD have a no voltage issue is in the connector the coil power wire plugs into, the wire itself or the connection to the coil... the other coil is getting power

3. does have power... Check the coil. Easiest way is to swap the 2/3 coil for the 1/4 coil physically and see if the problem follows the coil

4. coil bad? replace it;

5. problem stays on 1/4 side after swap? Either a bad igniter box or bad pickup coil. A Kaw Factory Service manual details multimeter measurements you can try on both the igniter and pickup coil.

The problem is very likely something simple like a loose wire so make sure your wiring is snug before performing surgery or doing any advanced trouble shooting.

del

Wiredgeorge and JMK,

Thank you for the ideas. I will try to get this straightened out soon, and let you know what I find. Fortunately I have the spare parts, I think, assuming I need some. It runs so perfectly fast and smooth when this glitch does not show up.

Hey apeman, how'd you make out with your electrical problem? Seems like I'm having a similar one to yours, except mine only clears up in spurts not for my ride duration!:dry: Thanks Mac

I didn't get to look at it yet since my earlier posts, above. this past weekend was filled with family obligations, and other stuff. Maybe later this week. I will let you all know what I figure out.

Now I'm having this problem as well. Is this crap contagious?! I also noticed that when it happens, my tack quits. :huh:

My biggest problem is that this doesn't happen when I find time to try and fix it. To quote apeman: I HATE INTERMITTENT ELECTRICAL PROBLEMS!!!

Think I found the source of the problem. The pickup coil for #1 and #4 quits as the engine warms up. Measured the resistance between the pickup coil leads for both, and only got a reading on the #2 and #3 pickup coil (within specs).

Then, after letting the pickup coil assembly cool off, the readings were normal for both. This still doesn't explain why the problem disappears after a while again though...

Think I understand why the tach quits as well after looking through my manual. What I didn't know is that the tach uses ignition coil signals.

So I guess I need a new pickup coil assembly. Couldn't find one on ebay, but perhaps Jeff can get me one? I'll shoot him a U2U.

Yes!!! I have finally tracked down the problem, and just like kzrider, it was the pickup coil.

However, I only found this out by trial and error (mostly error).

First, I cleaned and inspected all the wire connections -- no help.

Second, I cleaned and lubed my ignition advance mechanism -- no help.

Third, I replaced the ignitor with a spare -- no help.

Fourth, I swapped out the ignition coils with a spare set -- no help.

Finally, I swapped out the pickup coil -- problem solved!!!!!

Like kzrider, the fault in the pickup coil seems not to occur when the bike is cold, nor when it is entirely warmed up -- but only when the bike was partly warmed up. Strange, but then I do not understand the inner workings of electronic components. They are just a mystery box to me.


Anyway, THE BIKE IS FIXED, and runs like new again. (Plus I now have tested some of my spare components.)

Good for you!
I'm still waiting for my spare to arrive. Got one off e-bay for 10 bucks + shipping (hope that wasn't you selling your bad one ), so it would be a cheap fix. According to Jeff, the ignitors usually fry before the pickup plate, so I might go with a Dyna S if this doesn't work out.

kzrider wrote:

Now I'm having this problem as well. Is this crap contagious?!

I'm not kidding when I say this coil failure stuff is happening more and more.

Mine just died too, and I got a Dyna from Jeff because I figured I didn't want another 25-30 year old victim of the coil failure epidemic... For pete's sake, for $65, to me it was a no-brainer. An eBay one would be 1/3 to 1/2 that with shipping and stuff, but there's no guarantee...

I also have an intermittent loss on 1&4. I had an electronic ignition installed in 2004 and am now losing 1&4 once warmed up. Do I have pickup coils in addition to the electronic ignition or were they eliminated? Should I suspect the electronic ignition? I believe I have the original points. Would it be worth trying going back to the original system?