coil resistance

I have a 1982 KZ550C3 and I can't get it to run. I bought the bike last year and it ran for a bit but was hard to start and died a lot. I have replaced a few components but the same old problem persists. I fired it up today and the #3 pipe was cold. The problem seems to wander between cylinders (I seem to recall #2 and #3 being warm last year), so I'm thinking the problem is electrical.

The plugs & battery are new, and I checked to see that they're all firing. I'm getting a blue spark, but not a "fat" blue spark on all four (old plugs on old battery gave an orangish spark). I checked the coils and the primary resistance on both is just under 3 ohms... my Clymer says my coils should have 1.5 for primary. So is this my problem? Should I dump $120 at Z1 for new 1.5 ohm coils? Right now I'm hoping to not do serious mods, just get the thing running so I can ride before it snows (which is what happened year).

Thanks in advance,
Nick

Nick, If you have a bike that has an unknown past or uncertain maintenance record, first thing to do is check the compression. Have you done so? If not, I suggest you start there rather than replacing ignition components.

Your coils are supposed to be 1.5 Ohms primary resistance but you measure 3 Ohms. They may be aftermarket coils with an inline ballast resistor removed. It is common for Kaw to use lower resistance coils with a ballast resistor on an IC Igniter type ignition. Do the coils have any markings and what color are they?

Last, Once you have verified compression (do this with plugs removed using the starter to turn the engine and hold the throttle open), we can move on to other possible problem areas. You may be absolutely correct in that the problem is ignition related but you want to ensure that you are not wasting your time trying to diagnose an electrical issue if the valves are not closing and you have miserable compression which is often the case on a bike with unknown history.

Yeah, that's one of the things I wonder about but I don't have a compression tester. Does anyone know of a cheap one? Most I see are in the $120 range, and I'm not a huge fan of that. One of the things I did shortly after getting the bike was to remove the valve cover and check the valve clearances, and they were all within spec. So I'm hoping if the valve clearances are good, the compression should be good. I realize that this is not always the case.

The coils look like the pics of the stock coils in the Clymer, but I just went down to check it out to see the numbers. The coils are black with the following markings:

TEC
ZC006-TR12V
Made in Japan (go figure)

Do these sound like stock coils? If so, they should be 1.5 ohms... what effect would doubling the primary resistance have?

I recall checking the ignitor last year via the sequence in the Clymer; I haven't done it recently, but as I recall it checked out. The only thing I noticed as being out of spec was the coil resistance.

Thanks again
Nick

Your bike uses 2.4 to 2.6 ohm coils. I have several sets of coils from 550 C models. They are all 2.4 to 2.6. No ballast.

Post edited by: loudhvx, at: 2007/06/03 23:09

loudhvx wrote:

Your bike uses 2.4 to 2.6 ohm coils. I have several sets of coils from 550 C models. They are all 2.4 to 2.6. No ballast.

Okay, so it seems that the Clymer is wrong here as well. I couldn't find much info on these coils, other than someone on a Beemer list that said he was using them for a while with 2.5 ohm primary resistance (though I profess I don't know why anyone would use a Kawasaki coil on a Beemer). So I'll certainly buy that the primary should be in the 2.5 range.

That said, my last measurement had the coils at around 2.8 and 2.9, respectively. Would an additional 0.3 ohms make that much of a difference? I would think not, but then again, I think a lot of things...

Also, do you know what the spec is for the cap resistance? Or, better yet, what the resistance should be for the plug wire + cap? I realize the longer wires will have slightly more resistance, albeit little.

Post edited by: nick_borer, at: 2007/06/04 09:32

nick_borer wrote:

Okay, so it seems that the Clymer is wrong here as well.

Heh, how many times have I said that to myself? I wish I had a nickel for every time. :laugh:

Beware, there are a lot of mistakes in that 550 clymer manual, and in some critical details at that. I'm eventually going to try to make a corrected version.

Whether the .3 ohms extra is in your meter or in your coil, you are still dealing with a 1/4 century old set of coils. Replacing them, even if they work, would not be waste of money, unless you are really tight on cash. The only thing that ever got me stranded was a set of coils. They often fail during or right after a rain storm. I had two fail within 50 miles of each other after a rain-ride.

Post edited by: loudhvx, at: 2007/06/04 13:58

If your coils are supposed to be 2.5 Ohms and are reading 3 Ohms, I doubt it will make a tremendous amount of difference in the spark but as resistance does creep up, you will get a progressively weaker spark. The TEC coils are likely the originals as TEC makes OEM coils for Kaw and I can't recall seeing that brand sold in the aftermmarket although it is very possible they are sold.

As far as mistakes in a Clymer manual; I think they cut and paste a lot of info from one manual to the next as a LOT of info is pretty generic in nature and pull mistakes in as a result when it turns out there are model differences. For that reason, a LOT of the electrical info should be double checked as it applies to some model but NOT the model in your Clymers. Too bad that those folk don't have a feedback line so that they could fix mistakes in subsequent versions of their manuals. I never understood why they didn't have a blind feedback line for users to report errors. It would be neat for a user group, like this one to post a Clymers and have someone fix tech errors and add useful content. Guess there would be legal problems with this but it is what Clymers themselves should be doing.

So I have an el chepo Harbor Freight compression tester on the way; I realize that its readings will be suspicious at best but at the very least it will give me a comparative difference between cylinders. For $5 plus shipping, that's hard to beat, and eventually when I scrape together more dedicated cheese I will buy a good 'un. But staying on topic... so it seems that my coils are old, but should still be functional. I checked out Z1 and see that they have 1.5, 2.2, and 3.0 ohm coils available for my 550. Clymer says my coils are 1.5, loudhvx says they should be 2.4-2.6, and I believe him. So does that mean I could only get the 3.0 ohm coils from Z1 if I choose to get new ones? That would seem a waste, since I'm already at 2.8+ and worried that my spark seems anemic. Are there any good ignition mods if I ever go the route of replacing the coil? I see that Dyna likes to push its Dyna S ignition system, what does it take to get that all together, both components and $$$?

And just for the sake of completeness, can the IC igniter, plug wires, or plug caps lead to this as well? Plugs are new.

Thanks for the help!

Coils don't go BAD

3.0 ohm coils work fine with the stock ignition. If you will ever use a Dyna S, you definitely want the 3.0 ohm coils. If you are going to stick with the stock ignition, then you could use coils in the 2.5 ohm range. Make sure they are not the small coils meant for very sophisticated ignitions. (They will have a warning saying they are not for older electronic ignitions, or Dyna S ignitions).

There is a mod designed to replace your stock ignitor. It's more for DIY types sinceit requires some minor construction. It gives more consistent spark, but not necessarily more energy. If the coils are weak, the mod may not help. You can use 2.5 ohm coils or 3.0 ohm coils with the mod.
www.geocities.com/loudgpz/GPZgmHEImod.html
I prefer the 3.0 ohm Accel super coils.

If you are tight on cash, then you probably want to make sure the coils are the problem before replacing them. It's hard to determine, though if they are sparking at all. They may have leakage only under higher RPMs, etc.

Make sure you have full voltage to the coils. You should check out the coil-mod on WG's website for details.

Post edited by: loudhvx, at: 2007/06/06 13:38

I may check out the igniter mod after a few more diagnostics this weekend. I was hoping to do a little wrenching on Saturday, but of course the rain deamons beckon. Man, I miss the garage at my old place.

I did happen across the coil mod on WG's website and printed it out. Part of my diagnostics this weekend will be ensure that full voltage is getting to the coils. Of course, none of this matters if compression is low, so I'm waiting for my tester to arrive by mail. If everything checks out, it may just mean I have to get back into the carbs... ugh...

I hear ya. You always want to start with the motor... compression, valve clearance, etc. then electrical, then carbs. Hopefully, it won't come down to the carbs.