Coils

Hello! I just picked up a KZ from this kid down the road from me, and its a bit of a mess. I know it’s a 1984, KZ750, 4 cylinder. That’s about it, seems to have parts from a couple of different rides. It needs need rear turn single, and they are off a Harley. I don’t know which one yet. Back to the point, the bike doesn’t fire, but when you hit the starter it sounds like there is compression. The kid thought maybe the plugs were just fouled up to bad, I check them to see if they were getting power by putting a screw driver up the wire and holding it next to the exhaust and got nothing, so I had one of the coils check and was told it was dead.

So I wanted to know if anyone knew a good replacement coil? I think I will need a pair of them since none of the cylinders are firing. I got the bike pretty cheap and wanted to get it running for a couple hundred. I have dreams of a side car but that can be after it works!

Here are the pictures I have of it. I posted them on photobucket:
i23.photobucket.com/albums/b399/swb502/y...IVlDPssgQNfFyXjd.jpg
i23.photobucket.com/albums/b399/swb502/9...onYotIPlB9s4EAsR.jpg

dyna,accel or andrews make good coils or there are some used ones in the classifieds section im sure!

ditto the coil manufacturers kano mentioned, and welcome aboard....."Look everybody......new-to-the-forum guy that posted pics BEFORE we had to tell him!" Gold star for you!!:woohoo:

William wrote:

Hello! I just picked up a KZ from this kid down the road from me,....

Man that looks familiar.
Hi William, and welcome to the site.
Just out of curiosity, do you own a weird looking, and I mean _weird_ looking cat?

Ah no, no Cats. I am up in western NY, don't know if your in the same area or not.

Back to the topic at hand, would these works? kzrider.com/index.php?option=com_marketp...2&adid=865&Itemid=46

Post edited by: William, at: 2007/02/14 21:29

Seems unlikely to me that both coils would be bad and produce no spark. Are you certain that the coils have +12 volts? There are other components that you might want to check. Just my .02 but i'd make sure the coils really were bad before you throw parts at the thing.

I know non of them were firing so I took of one of the coils and took it to a shop. He didn't know the specs for them, but told me the one I gave him was dead. The fellow I got the bike off of told me they were getting power to the coils. I don't know whats before them or how to check how much power they are getting. I would think their is some sort of voltmeter like for the house? I have never done any eletrical owrk past basic circuits back in high school. So I am really shotting in the dark. Are thier wiring diagrams around for these things?

Post edited by: William, at: 2007/02/19 22:53

William, Howdy... If I can offer a bit of advice... Only take advice from folks where you have some hope of verifying the advice. The previous owner obviously sold the bike because he didn't know what he was doing. If I had the coil in question in my hand, I could "verify its specs in about 15 seconds" which tells me that the person at the shop may not know what he is doing. To test whether a coil is sparking, let's look at what you need to do for a second to MAKE SURE that the coils are really not sparking.

Keep in mind that you have two coils. One coil fires plugs 1 & 4 and the other 2 & 3. OK, with that in mind, remove plug #4. That is the one on the RIGHT as you sit on the bike (they are counted 1 to 4 left to right as you sit on bike). Put the plug back into its plug cap. Put the plug about 1/8" away from the engine cases and turn the bike over and look for spark. If you don't see one at this point, 1 & 4 coil is in question. Put the #4 plug back in and remove 3 and repeat to test for 2 & 3 sparking.

OK... one or both are not sparking, you should really check your wiring at this point. On your bike, you have an electronic ignition. The pickup coils are under the little round cover on the right side of the engine. There are two pickup coils and these correspond to the the coils. The pickup coil on the left is the 1 & 4 pickup coil. It has a BLACK wire attached. the one on the right has a GREEN wire and it is the 2 & 3. these wires, along with a couple of red wires (POWER) go to a connector that connects to your IGNITER box. This is the "brain" of your ignition. Check this connection. You might want to buy some contact cleaner at Walmart in the computer section and some dielectic grease from the autoparts store. Open the connector up and spray it and then coat the contacts with dielectic grease. If they are really corroded, you might want to clean them with an emory board a bit. OK, coming OUT of the igniter will be the same or similar colored wires... black, green and red. These connect into yet another connector that essentially has wires going to the coils. The coil with the green wire is the 2 & 3 coil and the coil with the black wire is 1 & 4. Make sure this connection is clean and lubed. Once you have traced the green and black wires from the pickup coils to the ignition coils, let's check for power at the coils.

DO NOT believe what the PO said on faith since the bike isn't working... Get a multimeter. Put it in VDC scale (20VDC or 50VDC is good). Put the red probe on the yellow/red wire hooked to your coil (it MAY be pink or light red but it ain't the black or green). Put the black probe on an engine ground like a cylinder head nut and turn the key on. Do you see 12VDC? If there is no power, the coils are not going to spark. See my web site for the "coil repowering" how-to. Might come in handy and it gives advice for checking the power at your coils.

Once you have checked wiring continuity and power to the coils, you can proceed troubleshooting the problem but the problem is most likely:
1. the way you checked for spark
2. wiring
3. power to coils

If it isn't, we can check the coils, the plug wires/caps and ignition after these checks.

I went out and picked up a multimeter and went to another shop today. This time the guy at the shop dose Kawasakis. He looked it over in front of me and confirmed it was dead, and then told me it wasn’t strange to see dead coils on this bike. He then wanted to sell me some $200 coils, but I passed for now. I went out an got a multimeter of my own. I started to poke around. I got 12 across the batter terminals so that was good. On the wires going to the coils however, I found something that I think is wrong. If I touched the positive wire to the coil and the negative battery terminal I got like 10.5, that I figured was ok. I got that for both sets of coils. If I did the positive to the coil and the negative off the coil I got nothing on either side. Dose this mean those are not hooked up some where?

Thanks for all the help. ~William

ELECTRICAL TROUBLE SHOOTING


www.dansmc.com/electricaltesting.htm

Please re-read my instructions and check to see if you have spark in the way I recommended. Next, the 10.5 VDC won't give you a very good spark. Do the coil mod I suggested. It is described on www.wgcarbs.com - You took your coil to someone who looked at it and determined it was bad? Did they have a coil testing machine? If not, they surely have no idea and were only trying to sell you parts. To test the coils, consider they have primary and secondary windings. The way coils fail is that the windings lose their internal insulation and short. To test, put the multimeter in OHMS scale on the lowest setting. With the bike turned OFF, put the leads on the two small lugs where the power and black or green wire is connected and measure the impedence. You should get somewhere between 3.0 and 4.5 Ohms. If the reading is significantly higher or lower, then the primary windings on that coil are in doubt. To measure the resistance of the secondary windings, keep the meter in OHMS scale but put it on 20K Ohms range. Put the meter leads inside the plug caps for that coil... 1 & 4 caps OR 2 & 3 caps and use the probes to touch the metal contacts. You can also pull the wires off (on some types of coils) and touch the contacts inside the coils that touch the plug wires. Anyway, the range here is much wider and will be between about 12K and 18K Ohms. A range above or below will indicate problems with the secondary windings.

Again, there are machines that test the function of a coil but these will be rare, even in a bike shop unless they are very well equipped. If the expert who checked your coil used such a machine, then his diagnosis might be accurate but if not, check them yourself as I recommended.

If you do the checking systematically as I suggest, you will find the problem and will be able to fix it. Good luck.

I love reading your posts, WG - it's good to learn something, every day

Thanks man!